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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Search for Medieval Warm Period

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Climate - the Movie: a hot mess of (c)old myths!

jimsteele at 06:07 AM on 3 April, 2024

A Netherlands journalist, Maarten Keulemans, tried to denigrate Climate the Movie: The Cold Truth in about 50 tweets using much of the same arguments posted to here on SkepticalScience. I successfully debunked all of his arguments in 16 tweets (originally I intended 20) listed below, and so I was just honored with being interviewed for a Dutch TV segment regards how the Climate the Movie promotes vital scientific debate. Too often alarmists try to suppress debate with weak arguments or denigrating the opposition as deniers. However I doubt alarmists can refute any of my arguments, but I will gladly entertain your arguments.

1 Denigrating the Climate Reconstruction graph by Ljungqvist https://twitter.com/JimSteeleSkepti/status/1771929435366940908…

2 Keulemans' Medieval Warm Period lie https://twitter.com/JimSteeleSkepti/status/1771933673488789868…

3 Contamination of Instrumental by Urbanization https://twitter.com/JimSteeleSkepti/status/1771939656504062260…

4 The Best USA temperature Statistic! https://twitter.com/JimSteeleSkepti/status/1771947116631580724…

5 Ocean Warming Facts https://twitter.com/JimSteeleSkepti/status/1771957182407536940…

6 US Heat Waves https://twitter.com/JimSteeleSkepti/status/1771963700951527487…

7 It is the Sun Stupid! https://twitter.com/JimSteeleSkepti/status/1771977013576024282…

8 Alarmists know better than Nobel Prize Winners ! https://twitter.com/JimSteeleSkepti/status/1771987039631921454…

9 Wildfires: Liar Liar Keulemans' Pants on Fire https://twitter.com/JimSteeleSkepti/status/1772000151596572844…

10 The Dangers of CO2 Sequestration and CO2 Starvation https://twitter.com/JimSteeleSkepti/status/1772016867265380795

11 Models Running Hot! Keulemans Disgraceful attack on the most honest Dr John Christy! https://twitter.com/JimSteeleSkepti/status/1772081300884852829…

12 Keulemans’ Blustering Hurricane Fears
https://twitter.com/JimSteeleSkepti/status/1772319957042479298

13. Dishonestly Defining Natural Climate Factors
https://twitter.com/JimSteeleSkepti/status/1773395443864736058

14. Denying Antarctica’s Lack of Warming
https://twitter.com/JimSteeleSkepti/status/1773473481637957758

15. Misinformation on CO2’s Role in Warming Interglacials during our Ice Age.
https://twitter.com/JimSteeleSkepti/status/1773777313924297210

16. Science journalists vs grifting propagandists – Antarctica
https://twitter.com/JimSteeleSkepti/status/1774428539858907444

A data scientist’s case for ‘cautious optimism’ about climate change

Eclectic at 21:32 PM on 2 April, 2024

William @4 , @5 :

William, you are again failing to think logically.

The people of the Global North are fairly well accustomed to deal with the cold. ( Even in harsh Greenland during the Medieval Warm Period, the farmers kept their cattle in the barn for 5 months of the year. Later, a 0.5 degreeC temperature cooling did not cause their societal collapse ~ that collapse was due to socio-economic changes.)

The coming problems of further global warming do affect the people of the impoverished "South". The poor cannot afford house airconditioning ~ even if the national electricity prices were halved. And airconditioned barns . . . are a fantasy. Like the idea of solar panels for barn coolers. And most of the poorest are a long, long way from (expensive) transmission lines.

Yes, agricultural scientists have done some good work in breeding for more heat-resistant staple crops. But nature imposes genetic limits, and there is no Get-Out-Of-Jail-Free card to ultimately save the day.

And the increasing sea level rise will also contribute to mass migrations. Think of "border crises" and demagogues ranting against them thar furriners. It will get a lot uglier than now.

William, you are intelligent enough to know all this. Please put aside your Motivated Reasoning, and skip past all the Denial, Anger, and Bargaining (and the Depression stage, too) . . . and move on to the Acceptance that real action needs to be taken against AGW.

John F. Clauser: the latest climate science-denying physicist

AB19 at 21:32 PM on 29 November, 2023

I quote from the article introduction:

"It’s a familiar story – the physicist who draws attention for declaring that climate scientists have got climate science all wrong. He (it’s always a ‘he’) was born before color television was invented, usually retired, perhaps having won a Nobel Prize, but with zero climate science research or expertise. William Happer."

I don't know if the writer of the article is a scientist or not but it starts with some rather unscientific viewpoints, namely by suggesting that male, retired physicists are not qualified to comment on climate matters. What does it matter what sex they are or how old they are? In relation to physicists, I don't know about the others in the list given, but William Happer would, I would have thought, certainly qualify to comment on the global warming debate given that if you have watched any of his presentations on this topic, you'll know that his field of research was the absorption of infra-red radiation by CO2 molecular stretches and bends - very apt in the climate debate I would have thought, given that it is precisely CO2 that is being posited as the culprit in current global warming trends. He also openly admits that he was once a climate alarmist until his work led him to believe he was wrong.
I am not a climate scientist- my background is chemistry- but there are certain apparent facts that appear to be ignored in the current debate, namely that we know the earth warmed before about 1000 years ago in the medieval warming period and again about 2000 years ago in the Roman period. These warmings cannot have been due to human activity given that there were no combustion engines or factories around and world population was vastly lower than today. I believe it's also true that in the last ice age the level of atmospheric CO2 was at least 10 times current levels - which according to IPCC thinking ought to have produced a blisteringly hot climate - yet there was an ice age. Whilst not denying that CO2 is x greenhouse gas, these facts do tend to cast doubt on just how potent a greenhouse gas CO2 really is. I believe Dr Roy Spencer, who is a meteorologist not a physicist and also not retired ( though he is male) has similar views to the listed physicists.

From the eMail Bag: Carbon Isotopes, Part 2: The Delta Notation

Bob Loblaw at 07:40 AM on 17 October, 2023

Rabelt @ 9, 11, 13, and 14:

You are really missing the big picture on carbon isotope ratios. The C13 levels alone are not "proof" that the fossil fuels are causing the atmospheric rise in CO2 - they are one line of evidence that rules out other sources. You are over-interpreting what you are reading here (or elsewhere).

This post is titled "Part 2". I suggest that you also read Part 1. It gives essential background about how isotope ratios differ across C12, C13, and C14, depending on the source.

You should also read Climate Change Cluedo. Steps 4 and 5 note the significance of changing C14 and C13 levels. To quote,

Declining C14 ratio indicates the source is very old, hence fossil fuel or volcanic (ie, not oceanic outgassing or a recent biological source);

Declining C13 ratio indicates a biological source, hence not volcanic;

Isotope ratios are also discussed on How we know human CO2 emissions have disrupted the carbon cycle, and on What is causing the increase in atmospheric CO2.

The caption on figure 3, which states that declining C13 ratios tell us it is fossil fuel combustion should really be interpreted as "the declining C13 ratio tells us that it is not volcanic. Since volcanoes are the only other possible source of C14-depleted carbon, the only remaining explanation is fossil fuels".

And none of those explanations require that C13 ratios be solely dependent on fossil fuel combustion. Figure 3 shows that for 800 years, C13 ratios were only slightly variable, and have now changed significantly once fossil fuel combustion began.

Your argument that "it changed before, so it can't be fossil fuels now" is just a peculiar flavour of the general "climate's changed before" myth that is number one on the hit parade listed on the upper left of every SkS page.

Just because you don't know of or understand an explanation does not mean that there isn't one.

It's cooling

Bob Loblaw at 22:39 PM on 6 September, 2023

CORK @ 330:

I see. You're in the group of people that say "how could we possibly know what happened in the distant past?

The simple answer to why the current warming is due to human emissions of CO2 is "physics". We do have information on past climates through geology - combined with understanding the physics involved. We know what physics can and has affected climate in the past, and we know that those processes do not explain the current warming - unless you also include the effect of CO2.

But as the moderator told you in comment 327 - this is getting off topic for this discussion. The moderator pointed you to the thread on past climates. Another post you may benefit from reading is the one on the Empirical evidence that humans are causing global warming.

It's cooling

CORK at 04:27 AM on 5 September, 2023

Climate's changed beforeWhat bothers me in the "Escalator" is the time scale. From 1970 to 2022 the temperatures rise, yes.

But this is not incompatible with a cooling at geological time scales. We may be in a rising part of the curve which will go down and over several 1000s of years the average will show a cooling trend.

The scale of time can be used and the curves can defend both arguments. Therefore the "escalator" is of no use.

The only pure fact in all the climate change saga is that humans are producing greenhouse gasses.

From that fact a whole theory of climate has been built. It is very difficult to say things like that without being insulted today.

2023 SkS Weekly Climate Change & Global Warming News Roundup #29

Bob Loblaw at 05:10 AM on 26 July, 2023

Wild and One:

I'm going to have to express some disagreement. Although in public discourse and discussion there may be reasons to keep emphasizing the links between human activities, fossil fuels, and changing climates, in the scientific discussion (which Skeptical Science tries to focus on), the terms such as "climate change" have specific scientific meaning.

Not all climate change is induced by burning fossil fuels or other recent human activities. Using vocabulary that fails to recognize that will lead to a risk of losing credibility. Number 1 on the SkS "Most used climate myths" is "Climate's changed before". Number 89 is "They changed the name from 'global warming' to 'climate change'." Number 209 is "IPCC edited out natural causes of climate change".

It's unfortunate, but you need to be careful on how contrarians will twist your words.

CO2 is not the only driver of climate

Bob Loblaw at 07:54 AM on 9 May, 2023

piotr @ 73:

I am not sure what your "not directly" statement refers to. I presume that the Martin Mlynczak quote is the one in comment 69. To put it simply, the thermosphere and the earth's surface respond to solar radiation in very different ways. You can read about the thermosphere on Wikipedia. Note that the thermosphere is at very high altitudes (>80km), and its temperature structure is the result of the absorption of UV radiation. It also has very low density, so even though average kinetic energy is high ("temperature") it does not hold a lot of heat. It is not strongly linked to the surface, which is heated by the absorption of solar radiation over the full spectrum.

This paper by Lean, Beer, and Bradley (1995) shows in figure 2 that variations in total solar irradiance are much less than for the UV range (in %).

Lean 1995 fig 2

To use the 4W/m² drop in that figure, you need to first reduce it by a factor of 4 (area of a sphere vs. area of a circle), and then adjust for global albedo (0.3), giving an overall forcing of only about 0.7 W/m². Sustained over only a period of about 50 years, this is not going to have a major cooling effect on its own.

You say that "it noticeabl[y]e cooled large parts of the no[r]thern hemisphere", which I presume is a claim with respect to surface temperature responding to these solar variations. You then throw in volcanic effects. You seem to grossly overestimate those solar effects, though - with no references to any supporting information. If you look at this SkS post, the first figure shows that reconstructed global temperatures for that period are much smaller than your claimed "decrease up to 1.5°C".

Temperature reconstructions

In your second paragraph, you start talking about "The past 10.000 years where up and downs in global mean temperature like +/- 2°C for dozen decades, even for nearly 2000 years - as we can reconstruct with little data-points." This starts to wander into the last glacial period, where Milankovitch cycles start to play a role. You are mixing together a lot of different forcing mechanisms, as if they are all equivalent in some fashion.

You then start into urban heat island effects, and finish off with a couple of paragraphs that represent an argument from incredulity. If you actually want to learn something about temperature reconstructions from proxies, Wikipedia has a decent article on this, too. The Wikipedia page also has a graph that shows even less variation in temperature than the one above:

The numbers you are throwing around in your "just imagine" scenarios seem to be ones that you have a lot of confidence in. The problem is that they also appear to disagree with broad swaths of the scientific literature. You appear to be claiming that science is unsure of what happened in the past - but you are. It seems highly unlikely that you are correct.

If you want to have any credibility here, you are going to have to provide references to the numbers you post. This is not a site where you will be permitted to post a lot of unsubstantiated opinion. As you are a new user here, I strongly suggest that you read the Comments Policy.

CO2 is not the only driver of climate

Eclectic at 05:51 AM on 9 May, 2023

Piotr @73 ,

Wind & ocean currents move heat energy around the planet - and so there is a considerable "averaging" effect on global temperatures. Even today, you do not need thousands of observation stations in order to assess changes in global temperature. Analysis shows that less than 100 stations are needed (if well-distributed, of course) to give a closely accurate picture of conditions.

A so-called Grand Solar Minimum is not actually very grand ~ studies such as Feulner & Rahmstorf, 2010 and Anet et al., 2013 indicate that a GSM produces a global cooling of around 0.3 degreesC. (Other studies indicate slightly smaller changes.) And this is because our Sun is a very stable star, with a very stable output of radiation. Very little variation.

Even the Little Ice Age was not spectacularly cold ~ a global cooling around 0.5 degreesC . . . which had been helped along by a number of cold winters from volcanic eruptions.

There have been periods of decades of marked cooling in the neighborhood of Greenland earlier in the Holocene, as a result in temporary changes in ocean currents. But these had little effect on average global temperature (the planet is big, and there is a vast amount of tropical ocean). The one exception is the millennium of strong cooling (the "Younger Dryas" ) about 12,000 years ago ~ and this was a one-off event produced by the single event of melt/discharge of the Laurentide Ice Sheet situated in Canada.

Piotr, you seem to have a wrong idea about earlier warm periods (of the Holocene) such as the so-called Minoan / Roman / Medieval Warm Period ~ these were only very slight changes, around 0.3 degreesC or smaller. These were only tiny "blips" on the general slow cooling from the Holocene Maximum temperature (slow cooling owing to the Milankovitch Cycle).

Possibly you have been misled by reports based on Arctic region temperature estimates (the Arctic shows bigger swings than the average global temperature).

There is no consensus

Rob Honeycutt at 10:24 AM on 20 April, 2023

"But Michael Mann showed us in his model that the medieval warm period and little ice age never existed so all those thousands of scientists that proved they did exist must be wrong."

a) Please look up the definition of the word "heterogeneous."

b) Assuming you're talking about MBH98/99, that was nearly 25 years ago and their research only went back too the MWP. Perhaps you should catch up on more recent research.

(Yes, this is quickly veering off-topic... as one would expect.)

There is no consensus

Albert at 09:46 AM on 20 April, 2023

"Such low ECS figures would mean the earth's climate should be almost perfectly stable over geologic time (no glacial-interglacial cycles) and we know that's not true."

Rob, believe it or not there are other factors that effect global temperature like, the sun, solar winds, magnetic fields, cosmic rays, transportation and retention and expulsion of ocean heat, volcanic activity above and below water, aerosols, clouds, gravitational pull of other planets, milankovitcg cycles, earth rotation wobble, shifting of poles, etc.

Our current warming cycle started around 1700 as The little ice age peaked negatively and we have been warming sporadically ever since.

its all perfectly normal with many historical precedents in the Holocene and previous interglacials.

1000 years ago Vikings colonised and farmed parts of Greenland that are still permafrost today. How can this be unless Greenland was far hotter than today. etc Etc etc.

But Michael Mann showed us in his model that the medieval warm period and little ice age never existed so all those thousands of scientists that proved they did exist must be wrong.

There's no tropospheric hot spot

MA Rodger at 19:23 PM on 23 August, 2022

Cedders @33,

And having had a read of that PDF...

Cedders @33,
Having examined the PDF (16 pages not 24), it is quite evident that it is a pile of utter nonsense, a "welcome to the lunatic asylum" message and not anything in any way scientifically-based.

The author is Piers Corbyn, a well-kown denialist and an elder brother of Jeremy Corbyn (a long-serving left-wing Labour MP who bizarrely gained the heady position of Leader of the Labour Party for 4½ years).

Piers Corbyn is described in Wikithing as "an English weather forecaster, businessman, anti-vaxxer and conspiracy theorist" and does feature here at SkS being (1) Cited within a spot of denialism of 2015 in the Daily Express tabloid/comic, (2) The main source of a pile of climate nonsense of 2013 from the then Mayor of London Alexander Boris von Pfiffle Johnson, a man now renowned throughout the known world for not being particularly truthful, (3) Listed here at SkS as a denialsit with zero peer-reviewed writings.

The 16 page thesis linked up-thread @33 is a 2019 thesis presented to the Reading University Debating Journal and sitting at the top of a list of 24 such theses posted 2018-19, top of the list because it is the most recent (the journal lasted less than a year), a list which addresses such important topics as 'Why Self-Service Checkouts are the Invention of the Devil' and 'The Great University of Reading Catering Con: Man Shall Not Live off Sandwiches Alone' and an anonymous piece 'Why I Support the Conservatives: The Most Successful Party in British History'.

The Piers Corbyn thesis begins by citing David Legates' dismissal of the 97% AGW consensus before dismissing that because "it is about facts; and no Global-Warming Inquisition is going to prevent me exposing their nonsensical theories."

Corbyn then kicks off by asserting anthropogenic CO2 comprises 4% of atmospheric CO2 (thus confusing FF carbon with naturally-cycled carbon) and that CO2 is not the main controller of global temperature (here presenting a graphic which confuses the US temperature with global temperature - shown below in this comment).
A further assertion is then presented, that CO2 is the result of warming oceans with six references/notes provided in support which seem to all point back to crazy denialist Murry Salby.

So, a la Salby, the present rise in CO2 is claimed to result from the good old Medieval Warm Period. A graphic is presented comparing a denialist 1,000y temperature record (based on the schematic FAR Fig 7c) with the much-confirmed scientifically-based Hockey Stick graph.
This brings us to the halfway page of Corbyn's denialist rant.

The thesis continues with pageful of misunderstanding of how the GH-effect works, ending with accusations that this misunderstood 'theory' breaks the 2nd Law of Thermodynamics (or it does if you misinterpret the 2nd Law of Thermodynamics).
Happily, this misunderstanding is considered to be not supported by "better scientists" who consider the lapse rate. And this indeed is a 'better' consideration. But here Corbyn perhaps confuses the tropical 'hot spot' (which is caused by increased tropical rainfall transporting more latent up into the troposphere) with some CO2 effect. (The 'hot spot' results from a warmer tropics and not per se any enhanced GH-effect.) And he fails to address the reasons why there is difficulty detecting this tropical 'hot spot'. Indeed he brands it as a 'coldspot' that he seems to say is caused by "more CO2 & other GHGs" which cause a diurnal fluctuation in the IR "heat-exit height" to become greater and, due to the 4th-power in the SB equation, this causes cooling. Whether such a phenomenon extends beyond the tropics (thus globally more-than negating the 'hot spot') is not properly explained but, due to the lapse rate this phenomenon can apparently also negate "the original expected surface warming."

A first graphic box is presented with three unsubstantiated bullet points explaining "Why CO2 theory does not work" alongside two similar "apart from"s.
A second graphic box also titled "Why CO2 theory does not work" states:-

In the real atmosphere there are day/night temperature fluctuations (eg in upper atmosphere). They are larger with more CO₂ because CO₂ (infra red absorber / emitter) gains & loses heat easier than N₂ & O₂ and so enables all the air to adjust quicker.

This is a fundamentally different explanation from the previous fluctuation in IR "heat-exit height" explanation described earlier, and it is still wrong.
(A packet of air with X concentrations of CO2 will both emit and absorb an IR photons of quantity P. With absorb=emit, it is thus in equilibrium. Add CO2 so the concentration is doubled to 2X, and the emitting photons will double to 2P and the absorbed photons will also double to 2P so absorb=emit and the same equilibrium is maintained. The main result is that twice the level if IR emission has half the pathlength before absorption so at any point the IR flux remains unchanged. And CO2 does not "gain & lose heat easier than N₂ & O₂" when it remains thermally coupled to the N₂ & O₂. )
The remainder of this second graphic box on PDF page 9 is a little too confused to rebut with any confidence. A diurnal range of "about 5 or 6 deg" is given which is apparently a temperature range yet whatever “deg” means (presumably Kelvin), the bulk of the troposphere has a far smaller diurnal range than even 5ºF. The mechanism for the enhanced cooling from the "heat-exit height" is presented as due to a fluctuating temperature losing more heat (by radiating IR) than a constant temperature (which is true). A rather dodgy-looking equation is followed by the note "Detail subject under research" but no reference is given and three-years-on there is no sign of such "research."
And a third graphic box is shown on the next page also titled "Why CO2 theory does not work," this third such graphic mainly presenting a pair of images from Australian denialist David M. W. Evans who has his own SkS page of climate misinformation.

The thesis then turns to the proposition that it is not CO2 but solar forces that "rules climate temperature" with the dotted line on the graphic below described as such a ruling influence. It apparently shows how the "9.3yr lunar-nodal crossing & the full 22yr solar magnetic cycle" allegedly shift the jet stream and "many circulation patterns." The graphic's 60-yr periodicity is less than convincing,being fitted to US rather than global temperature which, when extended beyond the 1895-2008 period shows itself to be simple curve-fitting (eg the Berkeley Earth US temperature record 1820-2020 does not show it, even to a blind man). The graphic was presented by Corbyn at the Heartland Institute's 2009 conflab in NY in which Corbyn [audio] insists other findings demonstrate “something is going on” but why it is this graphic being reused in this 2019 thesis is not clear – perhaps the forecast of world temperature dropping to 1970s levels by 2030 is too evident on other slides he used in that Heartland presentation.
To support his thesis Corbyn mentions an alleged cover-up by the likes of the BBC in reporting only global warming when the 'true' data shows cooling, the reported support for all this Piers Corbyn craziness from oil companies who shy away only because they want to use AGW to "make higher profits" and how these AGW-inspired mitigation agendas are already directly responsible for needlessly killing "millions" annually.
The thesis ends with a challenge:-

It is for this reason that I, Piers Corbyn, challenge whoever is willing in Reading University or other appropriate institutions to a debate on the failed Global warming scam vs evidence-based science.

So I interpret the thesis as a "welcome to the lunatic asylum" message from Piers Corbyn.
Piers Corbyn graphic

Clouds provide negative feedback

Bob Loblaw at 06:00 AM on 13 July, 2022

Likeitwarm:

The paper by Mulmenstadt et al that you mention was covered in this blog post at Skeptical Science, around the time it first appeared. (SkS reposted the Carbon Brief article.)

In that post, a key summary is:

However, the lead author of the study tells Carbon Brief that fixing the “problem” in rainfall simulations “reduces the amount of warming predicted by the model, by about the same amount as the warming increase between CMIP5 and CMIP6”.

So, the results are not as earth-shattering as you seem to want to imply. Uncertainties in cloud feedback are a well-known part of climate modelling and understanding, and this paper represents one more small step in helping understand the consequences.

As for your description of the water cycle:

A wet surface evaporates more than a dry one. This transfers energy as latent heat into the atmosphere, and reduces the energy transfer as sensible heat (thermal energy). Thus, it priimarily changes the balance in how the energy reaches the atmosphere, not the total.

What evaporates evenutally condenses and falls out as precipitation, but it rarely condenses or precipitates over the location it evaporates. Most extra water vapour is transported to other regions, where it falls as precipitation.

Oceans receive far less water via precipitation than they lose as evaporation.

Land areas (mostly) are the opposite - much more precipitation than evaporation.

Increased evapoation does not necessarily lead to increased cloud cover at the evaporation location. Any changes in cloud type, amount, etc., are strongly depndent on when and where and how that cloud eventually forms.

This complexiity is why cloud feedbacks are still an area of active study.

The current understanding remains that clouds provide neither strong negative or positive feedback.

As for your discussion of "runaway warming" - nobody is predicting such a result due to CO2, so you are arguing a strawman.

And as to "self regulation of the temperature of the atmosphere" - the simple fact that climate has changed in many ways, for many reasons, over centuries and millenia is strong evidence that this is not true. Perhaps try reading the "Climate's changed before" post that reponds to our number 1 myth listed in our "Most Used Climate Myths" in the top left sidebar of all our pages.

I have worked through some darn cold sunny days in winter - much colder than overcast days in summer - to illustrate how incomplete your cloudy/sunny day closing statement is.

How to inoculate yourself against misinformation

MA Rodger at 19:56 PM on 7 July, 2022

Petra Liverani @68,

I do not see any connection which would require you to begin the comment "Just to add,..." You appear to be suggesting that certain argument proves nothing yet will still be savaged by those responding.

Simply stating "The climate's always changed," or "CO2 is plant food" does not of itself contradict the accepted fundings of climatology. I think you would need to set out the use of such statements (& the responses) to be able to judge whether "the kind of responses" were inappropriate.

To provide such context for your "The climate's always changed" statement, the first listed SkS myth cites Dickie Lindzen who is an actual clomatologist but who has never accepted the science of AGW and has done a lot of work attempting to overturn that science. Yet despite his best efforts, he has established nothing and in his attempts to establish something has adopted many egregious arguments like "The climate's always changed."

Indeed, the climate has always changed but that does not prevent us understanding why it changes and thus seeing that it has not changed before like today's AGW. Even the PETM which was also driven by rising CO2 levels took tens of thousands of years when we are driving the climate in mere centuries.

The "CO2 is plant food" argument is listed as the SkS's 43rd myth which describes why elevated CO2 is not entirely a good thing for plants. And do note that the plants are not very hungry for CO2 as they are only eating up a quarter of the CO2 we serve up.

SkS Analogy 1 - Speed Kills: How fast can we slow down?

Eclectic at 10:38 AM on 19 February, 2022

Nigelj @38 :

speaking of Hockey Sticks and MWP's and vast lists of scientific papers

. . . leads us to one of PotHoler54's encounters with that well-known paragon of truthfulness, Lord Christopher Monckton :

(shown in PH54's video "Medieval Warm Period - fact vs fiction" )

Monckton speaks: "700 scientists from more than 400 institutions in more than 40 countries ... have contributed to papers that I know about, and can on notice list, saying that the Medieval Warm Period, which is well-known in history and archeology, as it is in climate science - was real, was global, and was noticeably warmer than the present."

in his video commentary, Potholer54 states :-

"Monckton was as good as his word, and when I asked him for the list, he gave it to me. Unfortunately, I am probably the only person who ever asked him - because the list doesn't live up to his claim. The 700 scientists who contribute to the papers listed, don't say the Medieval Warm Period was real, global and noticeably warmer than today - or anything like it."

Nigelj, I'm sure you won't be the least bit surprised.

[ There is more entertainment to be had, in a whole 5 (five) videos by PotHoler54, titled "Monckton Bunkum" . . . exposing Monckton's . . . er, taradiddles & self-contradictions. ]

SkS Analogy 1 - Speed Kills: How fast can we slow down?

Eclectic at 15:07 PM on 18 February, 2022

Santalives @25 ,

. . . as Evan says, you seem to be getting yourself bogged down with words & definitions. If the term "settled science" is something that sticks in your craw ~ then simply look at the science itself. Look at what is happening in the physical world of atoms, molecules, radiations and temperatures. The real world ~ not the rhetorical world of the propagandists & science-deniers.

# And thank you for the link to the list of papers provided by the notrickszone website (usually referred to as "NTZ").

From time to time, NTZ does come out with lists of 100's of papers, which NTZ alleges do overthrow the mainstream climate science. It is the "shotgun" approach, intended to impress the hell out of the layman who will never read anything more than the titles of the papers (if even that much). The layman who wishes to believe that all those 10,000+ scientists (worldwide) are massively wrong. The layman who doesn't wish to do some thinking (and legwork) for himself. This is very much the target audience for NTZ.

So, Santalives , please have a look in detail at about half-a-dozen of those NTZ papers, and get back to the readers here at SkS when you have identified one or two "killer arguments" from the papers (arguments or lines of evidence that the consensus climate science is wrong in some major way).

It is fair to warn you that NTZ has a track record of complete failure in this regard. (NTZ loves to "cherry-pick" ~ pick out a tree or two, while ignoring the forest.)

# Santalives , if you are not keen on doing a lot of climate reading (as is my impression so far) then you might enjoy viewing some YouTube videos by science reporter PotHoler54 who is a very knowledgeable guy ~ he debunks a lot of junk science & "fake media". His climate series (now 58 videos) range from 5 - 30 minutes. You could comfortably do one a day, and get up to speed about the climate controversies. All of the videos are informative, and most of them are amusingly humorous in parts !

One of the PotHoler54 videos from 2017 is titled: "Have 400 papers just DEBUNKED global warming?" And you guessed it ~ unsurprisingly the list of 400 papers comes via NTZ .

Another of his videos debunks Christopher Monckton's spurious claims about scientific papers regarding the Medieval Warm Period (MWP).

You will find PH54 very informative on the misrepresentations and deceptions practised by science-deniers such as Monckton, Heller, and others.

Climate's changed before

Eclectic at 10:49 AM on 13 July, 2021

. . . 2

TVC15 , a recent high-resolution sea-shore study [ IIRC - Kulp and Strauss 2019 ] indicates that a 1 meter SLR would displace approx 230 million people from their houses and farmlands. And factoring saline inundation by storm surge, there would be many millions of refugees displaced well before the "average" 1 meter rise is reached. So that's likely to be getting underway before 2100 even though the full 1m rise won't come until after 2100. And doubtless, some of these many refugees will need to settle in the neighbourhood of this denier's great-grandchildren. No social disruption at all !

And for a 2m rise in sea level, you can add a few hundred million more refugees . . . all wanting to go to higher ground . . . like Colorado, or wherever this unworried denier has been living.

Western droughts come and go - and sometimes stay for centuries, judging by the history of the last 2000 years. ( I'm sure your denier friend will tell the farmers and townsfolk, that they simply need to wait patiently, for a few generations or so.)

Note that the PAGES12k proxy studies show that world temperature is currently same or slightly higher than the peak of the Holocene - though many deniers still falsely claim that we are "colder than the Medieval Warm Period". Go figure !

It's planetary movements

Eclectic at 05:56 AM on 1 April, 2021

Likeitwarm : if I may add to Rob Honeycutt's comment :-

Your thinking seems muddled and confused.

A rise in temperature can cause a rise in atmospheric CO2. And a rise in CO2 can cause a rise in temperature (the last 200 years being an excellent example of that . . . and you can find other examples in the paleo history). But I suspect you already knew that.

Just to put things in perspective : the planetary temperature has been falling gradually for about 4,000 years ~ a fall of roughly 0.7 degreesC. The recent Medieval Warm Period [MWP] and the Little Ice Age [LIA] have been very small blips (around 0.3 degrees up or down) on that background decline. So the MWP and LIA have been insignificant in comparison with the overall trend since the peak of the Holocene.

But the modern temperature has now risen far above the MWP and is probably even slightly higher than the previous plateau of the Holocene ( 5-10,000 years ago ). And it is still rising fast. The onset of next major ice age (glaciation) was due in around 15-25,000 years' time . . . but is now postponed far beyond that time span.

Sadly, the movement of the planets Jupiter and Saturn have nix to do with the Earth's climate. But they may have some influence on your personal life, Likeitwarm ~ if you yourself believe in Astrology. (Are you a Cancer or a Capricorn perhaps . . . or more likely a Taurus ? Or perhaps all three ? )

It's planetary movements

MA Rodger at 21:19 PM on 29 March, 2021

Likeitwarm @Elsewhere,

You link to comment presented in Semi (2009-unpublished) 'Orbital resonance and Solar cycles' specifically p48 which says:-

The "wave" of approximate period of 934* years, which could also probably be anti-correlated with Sun spin rate, seems to match the climatologic events of Medieval optimum and Global warming, and also the Little Ice age of Maunder minimum, and similar periods in earlier ages (fig. 81)...
If this is right, now the Solar activity could drop a little, but will approach a larger maximum arround year 2050, not disturbed by the peak anomally, and then drop to a next little-ice-age arround 2400 AD. The time-lag between the spin rate change and activity change is still uncertain...

The periods of low scalar angular momentum (and higher Solar activity) roughly correspond to human civilization thriving: 1450BC Egypt, 600BC Greece, India and China, 200AD Rome and China, 1200 Medieval optimum (population growth in Europe), 2000AD (present "technical boom"). The periods of high scalar angular momentum (and lower Solar activity) correspond to crisis periods of human civilization.

According to this connection**, the current warming rate should slow down a little now, but will grow to local maximum arround year 2040, from which point it should drop to next little ice age arround year 2430 and to next warming arround year 2900. [**This referring to the paper's Fig 81 which plots the scalar sum of angular momentum of 9 planets and Sun with the climatologic data from Moberg et al (2005) which presents a 200-year NH hockeystick.]

This is all about a "wave" in the Scalar sum of Angular momentum and the page also presents a NOTE saying:-

NOTE: It was remarked, that Scalar sum of Angular momentum is a nonsense, which it is...

I think I would have to agree with this NOTE. Angular momemtum is considered maintained in a closed system and any heat-related effects that may work beyond a close system (the sun loses 130 trillion tons of mass a year through nuclear fusion) wouldn't make a great deal of difference to that, processes which themselves may show variation but again not significantly even if the sun's position relative to the solar-system's barycrentre were a factor (which Semi [2009-unpublished] asserts is when peak Scalar Sum of Angular Momentum occur).
Further to the NOTE, Semi (2009-unpublished) also does not set out this as an overall finding as it is unmentioned in either the abstract or conclusions.

Of course, that does not stop the swivel-eyed denialists. I note one of the two papers referencing Semi (2009-unpublished), Holmes (2018) 'Thermal Enhancement on Planetary Bodies and the Relevance of the Molar Mass Version of the Ideal Gas Law to the Null Hypothesis of Climate Change ' is cites Semi (2009-unpublished) as apparently showing "Yoshimura is in evidence throughout the climate system, and in proxy records, on all time-scales," (Yoshimura [1978] being cited to support a 55-year barcentric solar-system cycle but with zero actual mention of Earthly climate in that paper).

CO2 is not the only driver of climate

Likeitwarm at 13:42 PM on 29 March, 2021

I feel that I am a total neophyte, I have a lot of respect for the understanding of the atmosphere that resides in this forum.
I don't deny the atmosphere has been warming for the past 200 years or so.
In looking around the internet for answers, I recently read about a planetary cycle described by P.A. Semi at http://semi.gurroa.cz/Astro/Orbital_Resonance_and_Solar_Cycles.pdf page 48.
He says this 934 year cycle coincides with the relatively short cycles of climate change, i.e., medieval warm period and medieval cold period(little ice age) and prior.
If this cycle is fact, then the earths climate is warming now from natural processes coming out of the "Little Ice Age" and CO2 may not be the driver of recent warming of .9 deg C of the last 170 years.
I'd love to know what others think of this.

Skeptical Science New Research for Week #7, 2021

Bob Loblaw at 03:43 AM on 21 February, 2021

Jamesh @ 8:

As you seem to be struggling to find appropriate places to discuss stuff, let me try to help you.

First, The the most recent ice sheet to cover New York State would have been the Laurentide Ice Sheet, which covered pretty much all of Canada and the northern US states. It had several distinct and somewhat independent areas of motion, though. "Polar" is probably not a good descriptor for it.

https://en.wikipedia.org/wiki/Laurentide_Ice_Sheet

If you want to argue that it represents evidence that climate has changed before and therefore humans can't be the cause now, then the reasons why that argument are wrong is #1 on the Most Used Climate Myths page "Climate's changed before":

https://skepticalscience.com/climate-change-little-ice-age-medieval-warm-period.htm

If you want to use it to argue that climate scientists were predicting a return to ice age conditions in the 1970s, then the reasons why that argument are wrong is #11 on the Most Used Climate Myths page "Ice Age predicted in the 1970s":

https://skepticalscience.com/ice-age-predictions-in-1970s.htm

If you want to use it to argue that we are now heading into another glacial period, then the reasons why that argument are wrong is #14 on the Most Used Climate Myths page "We're heading into another ice age":

https://skepticalscience.com/heading-into-new-little-ice-age.htm

If you want to use it to argue that the current warming is just a continued pattern from a previous cold period, then the reasons why that argument are wrong is #48 on the Most Used Climate Myths page "We're coming out of the Little Ice Age":

https://skepticalscience.com/coming-out-of-little-ice-age.htm

If you want to use it to argue that climate follows natural cycles and the current warming is no different, then the reasons why that argument are wrong is #56 on the Most Used Climate Myths page "It's a Natural Cycle":

https://skepticalscience.com/global-warming-natural-cycle.htm

If you want to use it to argue that you know of some special factor affecting climate that climate science has ignored, and you are the only one that knows this, then you might want to go to Climate Myth #130 "Climate Skeptics are like Galileo":

https://skepticalscience.com/climate-skeptics-are-like-galileo.htm

If you want to use it to argue that humans can survive large shift in climate, then Climate Myth #197 "Humans survived past climate changes" is your destination:

https://skepticalscience.com/humans-survived-past-climate-changes.htm

Skeptical Science New Research for Week #7, 2021

Daniel Bailey at 03:39 AM on 20 February, 2021

Basically, jamesh's point he wishes to contest (the existence of land-based ice sheets that have since disappeared, like the Laurentide Ice Sheet) is a variant of the skeptic argument, "The Climate Has Changed Before" (so therefore this iteration of climate change is normal).

He needs to take his argument to that link, where I'm sure it will be prompted and thoroughly refuted.

After all, that the climate changed naturally before the impacts of humans became the dominant forcing of climate is uncontentious.

That the impacts of human activities are now the dominant forcing of climate is equally uncontentious, from a scientific basis.

It's waste heat

MA Rodger at 23:43 PM on 15 February, 2021

Bob Loblaw @200,
The craziness engendered in this thesis set out in both Bian (2019) 'The Nature of Climate Change-equivalent Climate Change Model’s Application in Decoding the Root Cause of Global Warming' and Bian (2020) 'Waste heat: the dominating root cause of current global warming' is profound. Other than having access to more recent data, the second account sets out nothing new that I can see, and there is little point in spending much time examining such madness.
I note the citations made by the second account (which are quite sparce) include two to SkS webpages, this one and 'What does past climate change tell us about global warming?'.
So from this SkS webpage the author does appreciate that the global primary energy use amounts to just 1% of the positive forcings from AGW. Indeed, this disparity he considered too small as, in the universe inhabited by Qinghan Bian the energy employed in "useful work" is somehow swept from the planetary climate system and will not contribute to a planetary energy imbalance. Given the "perspective of thermodynamics" invoked at this point in the narrative, the blundersome efforts of Qinghan Bian seem to know no bounds.

You point to the climate being modelled as having a pond-depth of ocean and a similar height of atmosphere. Adopting such nonsense allows temperature increases to be equated to global Primary Energy Use (bar the 20% that magically disappears in "useful work").
The earlier account gives annual values for the energy employed heating the various components of the planet. Thus in 2017 there is 1,500Kj x 10^14 warming the ocean surface layer. The OHC measurements give the 0-2,000m warming for 2017 as a little low relative to earlier years, averaging out at 7.8Zj annual. So in Bian-money, that is 78,000Kj x 10^14.
Some may consider this comparison a little unfair given ΔOHC is usually seen as being perhaps 80% of the heating resulting from AGW. This would put the total planetary on-going warming at some 100,000Kj x 10^14 which would compate with the 4,000Kj x 10^14 of Bian but only if the global temperature rise so far is ignored. The +1ºC extra planetary temperature which requires maintaining. If this AGW-delivered-so-far is also factored in, the extra energy flux out into space would be balancing 3.7Wm^-2 of forcing/feedback (and presumably with a ration of perhaps 1:2) giving a figure for the global forcing (20Zj balanced forcing+ 10Zj imbalanced forcing still heating) at 300,000Kj x 10^14. So very roughly the 1% value of [Primary Energy Use]/[AGW] appears again.

Climate's changed before

Eclectic at 12:10 PM on 22 October, 2020

MA Rodger @835,

Thanks. Yes, I had heard that the "frozen Thames" events had occurred even during the Medieval Warm Period (though those are never mentioned by Denialists).

I was interested in the "meme" of Thames freezings being held up as an example of the world-chilling severity of the Little Ice Age. And as I was saying to Hal Kantrud (who seems just starting out on learning about climate science) . . . the main point to remember is that the LIA and the MWP were pretty small beer compared with earlier climate changes.

As you yourself know very well, the LIA is greatly misrepresented by the climate-science Deniers :-

(a) Firstly, they exaggerate its severity ;

(b) Secondly, they falsely claim that our modern rapid warming is (somehow) "just a rebound from the LIA" .

(c) Thirdly - with amusingly unintended irony - they claim that the huge temperature excursions of MWP & LIA make the modern warming look insignificant . . . and yet at the same time they claim that the planet's Climate Sensitivity is so very low that we need not be concerned about the "slight" warming effect of anthropogenic CO2 emissions. Superb!

MA Rodger, you might not have seen it . . . but on one of the Denialist blogs recently, a particular Denier asserted that (by his calculation) Earth's Equilibrium Climate Sensitivity was around 0.4 degreesC. Improving on that, he then (based on the negligibly-small rise in CO2 which he attributed to humans) calculated that, of the modern warming, only 0.02 degreesC was human-caused. To repeat: 0.02 degreesC. Not a misprint. (Ah, who needs to pursue comedy, when so much is freely available on the Denier blogs! )

Climate's changed before

MA Rodger at 23:11 PM on 21 October, 2020

Eclectic @834,

Do be aware that London's frozen River Thames was a very rare event and if anything provides evidence against the Little Ice Age being something exceptional with reported freeze-ups occurring even during the Medieval Warm Period. There were perhaps only a half dozen Frost Fairs listed in the records and they stopped appearing, not because of warmer winters but because the old London Bridge was demolished and the river embanked.

Given such reasons for the absence of Frost Fairs since 1813, perhaps a better river to look for evidence of a Little Ice Age (or lack ofevidence) is the Rhine which is recorded freezing 14 times since 1784, the last time in 1963. Of those 14 freezes, most occurred well after any Little Ice Age with seven during the 20th century.

Climate's changed before

Eclectic at 09:12 AM on 21 October, 2020

Hal Kantrud, the planetary "wobbles" are much too slow to cause any brief effect such as the Little Ice Age [LIA].

Have a look at the PAGES 2K study.

Many people hear the name "Little Ice Age" ~ and combine it in their mind with old illustrations of Dickensian snow and London "Ice Fairs" on the frozen Thames, and suchlike Christmassy freezes.

But in reality, the LIA was very minor. Less than 0.5 degreesC colder than the usual background for the Northern Hemisphere, and more like 0.3 degreesC cooler for the global whole.

Even the Medieval Warm Period [MWP] was only around 0.3 degreesC warmer than the global historic background. Despite some of the trumpet-blowing about the MWP and the LIA, they were both pretty minor events overall. Their names do greatly exaggerate their size. And they are insignificant compared with the level of warmth of the Holocene Maximum (about 8000 years ago) and the even higher temperature levels of recent decades (which are around 0.5 degreesC hotter than the Holocene Maximum).

Climate's changed before

Tom Dayton at 08:32 AM on 21 October, 2020

Hal Kantrud: The "Little Ice Age" (LIA) was not a glaciation in any sense. It was a brief period within which some particular regions got colder for a little while before getting warmer again, but not all of them at the same time. From the PAGES 2K study:

"Our regional temperature reconstructions also show little evidence for globally synchronized multi-decadal shifts that would mark well-defined worldwide MWP and LIA intervals. Instead, the specific timing of peak warm and cold intervals varies regionally, with multi-decadal variability resulting in regionally specific temperature departures from an underlying global cooling trend."

YouTube's Climate Denial Problem

Eclectic at 23:51 PM on 10 April, 2020

Thanks Nigelj , yes I do read Realclimate from time to time (and note your presence there too ).

Now I am reporting back after reading the first article listed on Page One of climatescience.org.nz

# It is a fine example of one style of Denialist propaganda.

The article is titled, in very large blue letters in upper case :- [ * Moderators please excuse my use of upper case for this exact quote] :-

" DROP IN NUMBER OF SUNSPOTS SIGNALS IMMINENCE OF A COOLER WORLD "

~ this is followed by a single paragraph in small font, commencing:

" An important new paper by Dr David Whitehouse for the Global Warming Policy Foundation reveals that 2019 was mostly without sunspots. ... [and finishing:] This paper discusses some of these issues." With LINK to the GWPF important new paper .

Note the typical Denialist technique:

(A) The huge headline indicating Imminence of a Cooler World ( i.e. that the mainstream scientists are wrong about ongoing global warming)

(B) An entirely unrigorous newspaper-supplement-like report (by Dr Whitehouse) is implied to be a respectable scientific paper. It is no such thing.

# The editor of this website knows that many of his Denialist clientele will not bother to read past the headline, and they will proceed elsewhere holding the comforting knowledge that the planet is about to enter a cooling phase.

And that those who do actually read the single paragraph, also will proceed elsewhere, holding that same "Cooling" impression.

(C) Those who do follow the link, are met with a multi-page essay headed by beautiful huge photos & artistic illustrations of close-up views of the sun (all looking a bit National Geographic sciencey). Followed by 8 pages (plus sciencey reference list) of Whitehouse's text ~ discursively discussing cherry-picked famine in 17th Century France; horrible child mortality in Europe during the Little Ice Age; dire comments from a sermon by a contemporary English preacher . . . and various other irrelevancies including historical aspects of sunspot observations.

In the end, Whitehouse has given no quantification of the implied Grand Solar Minimum which is "imminently" about to strike us. Indeed, regarding future climate, he hasn't really said anything at all. His "important new paper" is lurid but vacuous commentary.

As such, it all comes as no surprise to regular readers of SkS.

Nigelj , I fear that the rest of the NZ website's headlines probably have a similar modus operandi. Is that correct? (And does that website have comments columns?)

I am very much reminded of that propagandist, the marvellous Lord Monckton who boasted that 400 scientific papers demonstrated the worldwide nature and much-higher-than-today warmth of the Medieval Warm Period. When science-journalist Peter Hadfield (Potholer54) challenged him for the list, Monckton blandly supplied the references [actually a list by Dr Idso]. Hadfield said that he carefully studied the first 6 papers on the list, and found none of them supported Monckton's MWP claims. So no point reading further down the list. (Monckton is well known for his bold mendacities/errors.)

1934 - hottest year on record

Eclectic at 16:18 PM on 1 February, 2020

Map @109 , the chart at Figure 2. shows a very strong warming from about 1975. In the early part of that century, there were some colder years around 1910 ~ but no strong trend 1880 - 1930.

I think you would need to do some careful statistical analysis, to demonstrate a trend there. AFAICT, there's nothing much. Taking a wider swathe of data, pre-1910 , shows a gradual & slight warming trend from mid-Nineteenth Century, but it's rather weak. There are of course fluctuations, from clusters of large volcanic eruptions, or from slight variations in solar output or from El Nino events. All part of the natural random variations . . . plus possibly (and dubiously) some multidecadal oceanic overturning currents (but these are only very slight in their effects ~ if they exist at all, and are not simply figments of imagination as humans indulge their tendency to see "shapes & patterns" in random data points).

Map, I suspect you are "seeing" trends that don't exist.

Weather tends to vary around the cyclic seasonal changes, because it is small-scale fluctuations against a global (hemispheric) background . . . but climate change requires major alteration in global-level gain (or loss) of heat energy over a sustained period of time.

The important point with climate, is that climate does not change unless something causes it to change. That's why the often-seen idea that our modern period of warmth is just a "rebound" from the Little Ice Age . . . is a complete nonsense.

Map , if you wish to step back and look at temperatures of the entire Holocene period, then it becomes apparent that the world has been in a gentle cooling trend for roughly 5,000 years ~ which would have continued (owing to the Milankovitch orbital change) but for the modern strong warming from AGW. The LIA and Medieval Warm Period were only very slight alterations of the underlying cooling trend. But that long term cooling trend has been so gradual as to be invisible on the scale of a few decades or a few centuries.

Your "2030 speculation" is baseless. Even the idea of a possible Grand Solar Minimum is (if it were to occur) something that would be swamped by the ongoing warming effect of rising Greenhouse Gasses.

Video: Is CO2 actually dangerous?

Eclectic at 11:49 AM on 2 December, 2019

BillyJoe @12 , you must certainly be "a glutton for punishment" ~ being up to Potholer54's video #35 already! But they are a bit addictive in their humorous style.

I would be interested to hear your critique of his videos, and especially about any errors you notice. Off the top of my head, I can think of the way he somewhat "up-played" [is that a word?] the magnitude/extent of the Medieval Warm Period ~ but then again, the video was made in 2012, before the publication of later research. And again, his comments may have been intended rhetorically to "draw in" the more Conservative viewers and lull their initial antagonism.

If you do comment further, I hope it can be on this thread. Possibly the moderators will approve it as being on-topic, as videocentric comment (not just ClimateAdam's videos). Katherine Hayhoe is an excellent speaker, too. Quite a star performer !

Top 10 most viewed rebuttals in September and October 2019

Eclectic at 21:36 PM on 13 November, 2019

(This post is transferred from an erroneous position in another thread)

Independently, I can supply a confirmation (semi-quantitative) of a spike in "climate inquiries" in September this year. Though I wouldn't care to speculate whether the surge of interest comes from the activities of "St Greta of Arc(tic)" or from the Extinction Rebellion actions or from climate action week or whatever.

I am a fan of the excellent & amusing Youtube video series produced by Potholer54 (science journalist Peter Hadfield). These debunk climate myths and expose the fabrications and misrepresentations of some of the prominent Denialist propagandists.

As a little project to engage some of my spare moments, in June this year (and through until today) I jotted down at intervals the cumulative viewing numbers for each of Potholer54's videos. Now typically, a new video receives a flurry of viewings, presumably mostly from notified subscribers of the series . . . and then the viewing rate decays to a lower level (which might be only 5~10 per day for certain videos, yet over a 100 per day for the more popular videos).

However, I noticed a surge in viewing rates in late September through to mid October. The most prominent surges were for about 10 particular videos ~ where the viewing rates rose to around 3~5x the usual background rate.

So, quite a remarkable increase. (Numbers have fallen away since then.)

My record-keeping has been more casual than rigorous, and I don't have a spreadsheet record to permit better analysis.

Not sure how much more can be teased out of this information: but for those who are interested, these are probably the "most surged" titles :-

1. 1.Climate Change - the scientific debate

25. 23-Medieval Warm Period - fact vs fiction

28. 26-Science vs the Feelies

33. Response to "The Global Warming Hoax Lord Monckton & Stefan Molyneux"

34. Response to "DEBUNKED : Top 5 "Climate Change" Myths by Louder with Crowder

35. Are humans contributing only 3% of CO2 in the atmosphere?

39. Top 10 climate change myths

40. A conservative solution to global warming (Part 2)

47. How accurate are scientific predictions about climate?

Warning: the left-hand numbers are the numeration used by Youtube for the videos. But some of the early videos have an older numeration which is incorporated in the video title [as you see, above]. Easy to confuse!

Science vs the Feelies is a particularly amusing and instructive video, regarding the "intuitive" thinking behind some Denialists.

Regular readers at SkS may enjoy the videos, and may gain something useful from the comment columns underneath. Of course I don't mean from the Usual Suspects / the trolls / the loonies etc ~ but I mean that one must admire the deft way Potholer54 responds to them. He emphasizes that he is not presenting his opinions, but is simply presenting the science (which is found not in newspapers & blogs, but is found in the peer-reviewed scientific papers of respected scientific journals).

The Experts Have Spoken: Disbanded Particulate Pollution Panel Finds EPA Standards Don’t Protect Public Health

Eclectic at 20:15 PM on 12 November, 2019

We don't have the means to shift your comment but please feel free to copy and repost it to the appropriate thread. It's certainly congruent with our observations, and worth noting in the right place.

As a little project to engage some of my spare moments, in June this year (and through up until today) I jotted down at intervals the cumulative viewing numbers for each of Potholder54's videos. Now typically, a new video receives a flurry of viewings, presumably mostly from notified subscribers of the series . . . and then the viewing rate decays to a lower level (which might be only 5~10 per day for certain videos, yet over 100 per day for the more popular videos).

So, quite a remarkable increase. (Numbers have fallen away since then.)

My record-keeping has been more casual than rigorous, and I don't have a spreadsheet record to permit better analysis.

Not sure how much more can be teased out of this information: but for those who are interested, these are probably the "most surged" ten titles :-

1. 1.Climate Change - the scientific debate

25. 23-Medieval Warm Period - fact vs fiction

28. 26-Science vs the Feelies

33. Response to "The Global Warming Hoax Lord Monckton & Stefan Molyneux"

34. Response to "DEBUNKED : Top 5 "Climate Change" Myths by Louder with Crowder

35. Are humans contributing only 3% of CO2 in the atmosphere?

39. Top 10 climate change myths

40. A conservative solution to global warming (Part 2)

47. How accurate are scientific predictions about climate?

Science vs the Feelies is a particularly amusing and instructive video, regarding the "intuitive" thinking behind some Denialists.

CO2 was higher in the past

nyood at 05:33 AM on 2 November, 2019

According to this recent study we have a way more accurate view on this issue now:

Schwark2019

In the Hirnation Event Summary:

"Massive perturbations of the atmospheric and hydrosphericcarbon cycle occurred with CO2concentration varying between 8-16 x PAL and near PAL over short periods of time." PAL means Present Atmospheric Level.

This is quite remarkable, it tells us that a glaciation is capable to absorb even CO2 ammounts of 6000ppm. It does not matter how high CO2 Levels are, a glaciation will happen when the following event occurs:

Sufficent Landmasses within the Polar Circles (LPC).

Going through all time periods, we can show how decisive landmasses at the polar circles are. Note that the polar circles represent a very narrow area at the north and south borders on these pictures. Greenland todayis a good example as it forms the only northern ice shield, mainly being within the arctic circle, while edging Canada and Russia are not inland iced.

Cambrian warm period, Landmasses in the Polar Circles (LPC): 0%-10%

Cambrian

Ordovician hirnantion glacial event antarctic LPC 100%:

HirnantionEvent

Silurian cold LPC antarctica 90%:

Silur

Devonian warming LPC 10% - 40% :

Devon

Carboniferus glaciation, Continents drop back to the south pole antarctic LPC: 90%-100%

Karbon

Permian Cold with late permian transition towards mesozoic Pangea arctic LPC 80% - 100%:

Perm

Triassic warming, antarctic PLC 10%-20%, arctic PLC 70% to 90%. only Southern PLC decisive? Arctic inland ice forming reversed with the jurassic? Triassic north pole contradicton.

Trias

Jurassic, Landmasses moved away from the arctic cycle. arctic LPC 10%-20%. antarctic LPC 5%-10%.

Jura

Cretateous, sea level rise noticeable, deglaciation at its maximum, transition to upcoming glacial period, Antarctica moving south. Antarctic LPC 80%-100%:

Kreide

Today, Cenozoic glacial period Antarctica resting at the pole once again. Greenland LPC 10% -20%, Antarctica 90%-100% LPC.

With an Ockham attempt i want to make 3 main arguments on why CO2 is not needed and not likely to play any thermal role at all:

1.Faint Sun Paradox,Snowball Earth and the Hot House Equilibrium.

The faint sun paradox is not a paradox. It is another evidence of how strong the terrestial force Ice Albedo is and therefore again the continental distribution.

Even with a 25% lesser sun, Oceans occur,hence the term "paradox".While precambrian snowball effects due to a supercontinent at the south pole, demonstrate the lesser sun effect.

The so called paradox underlines the trumendos forcings of Albedo and it describes the fundamental drive towards a hot house equilibrium whenever the poles are uncovered by land.

This Basic heating Trend that is strong enough to even compensate the faint sun paradox puts CO2 further away from having any thermal influence. This basic heat trend is documented by all the terminations of glacial epoches and even more so in the precambrian, with a barrier where no more heating seems possible.

So we keep in mind that we have a Glacial period during the ordovician to the early silurian, with Co2 levels around up to 6000ppm.

2. Carboniferous CO2 Levels

The carboniferous marks the point where the flora takes an increased influence on CO2 levels.

T°Co2overview

The late devonian till the middle carboniferus show how CO2 is absorbed while temperatur takes ~90 mio years to "follow".The reason temperature goes down is as usual, the continental drift towards the south pole.

What we eventualy see is a double decline in CO2.

The jurassic-cretaceous meeting of CO2 and temperature speaks for itself.

3. Today,GISS and an estimated CO2 sensitivity of 1,5°C

The uncertenty itself on the CO2 sensitivity after 30 years of research tells us per se that the science is not settled. IPCC on a global warming of <ahref=https://www.ipcc.ch/sr15/chapter/chapter-1/>1,5°C

"Past emissions alone are unlikely to raise global-mean temperature to 1.5°C above pre-industrial levels (medium confidence)"

"1.5°C emission pathways are defined as those that, given current knowledge of the climate response, provide a one- in-two to two-in-three chance of warming either remaining below 1.5°C

or returning to 1.5°C by around 2100 following an overshoot."

GISS actualy does show us a trend towards 1°-1,5°C ~2100 a.d. It is the natural interglacial trend. There is no evidence that our warming period is unique in its rate of warming compared to past medieval epoches

or to the past 11 Interglacials in our ice cores

The lowest model called the "russian model"

What is with Planck and Bolltzmann? my guess is Lüdeckepage19
and others are right, the saturation is already reached at PAL with 1°C

Since the Ordovian showed how much CO2 can be absorb in the oceans, acifidication of the ocean due to human emissions might be the bigger threat. Even though most of the CO2 was embeded in limestone, hence the CO2 "starvation".

It's cooling

Tom Dayton at 01:35 AM on 14 October, 2019

Richieb1234: Regarding the Medieval Warm Period, see this post. For a more recent and better temperature reconstruction see here.

Was Greenland really green in the past?

Eclectic at 10:34 AM on 26 September, 2019

JDG @31 ,

I certainly agree with your last paragraph. (But not so much your final sentence ~ "boom and bust" sounds like a business sector. The Greenland Viking saga was closer to "extinction event". )

From a climate point of view, it was a rather small decline in temperatures from the Medieval Warm Period . . . and it should not have been enough to extinguish the Viking colonies.

As you have noted, it was a combination of factors (including a failure of appropriate adaptation) which caused the collapse. I used the word "geopolitical" as an umbrella term for the various events: an increasing southward push by the Inuit; taxational pressure from Copenhagen; increased competition from Russian suppliers of walrus ivory & renewed elephant ivory supplies from Africa. Including a societal change in Europe ~ there was a gradual fall-off in demand for ivory as a luxury good.

Like the average plane crash: a number of adverse circumstances came together.

The climate Take-Home Message is that the decline of the MWP was too trivial a matter to finish off the Greenland Vikings.

Medieval Warm Period was warmer

Eclectic at 16:46 PM on 24 September, 2019

JP1980 @265 ,

as Scaddenp (@266) indicates, there is much that is wrong with KalteSonne's blog article.

In the first paragraph, the blog asserts that the MWP was hotter (or "similar") in temperature to today. Which is false. Various types of proxy temperature measurements show that the Medieval Warm Period was cooler than today's global climate. In addition, the land ice-shelves and glaciers were larger than today's, and the mean sea level was lower than today's. All these three types of evidence demonstrate the warmth of today and the relative coolness of the MWP.

KalteSonne is indulging in wishful thinking — not scientific thinking. Having made such a blunder to start with, it is not surprising to find that there are subsequent errors.

In the second paragraph, he [presumably he] goes on to present a misleading picture by taking quotes out of context. He misrepresents the message of the IPCC. And he fails to understand that the MWP was such a slight deviation of average world temperature, that one would of course not expect it to show up in a "hindcast" of computational models based on 20th/21st Century climate. (Hence his attack on climatologists' models — an attack which seems to be his underlying purpose in discussing the MWP.)

A further failure of KalteSonne, is his failure to acknowledge (to himself and to his readers) that the current warming event is not only larger and definitely worldwide . . . and that it is greatly faster & has a continuing steep upward trajectory ~ all of which is distinctly different from the MWP.

Clearly, he fails to understand the mechanisms causing climate change.

In short: KalteSonne's ideas are nonsense.

Medieval Warm Period was warmer

MA Rodger at 16:52 PM on 22 September, 2019

tmillion @263,

The 'work' you link to is actually a piece of denialist 'research' saying it is trying to answer such questions as "How could it have been so warm one thousand years ago when CO2 concentrations in the atmosphere were on a low pre-industrial level?" Note the links provide are to WUWT and CO2Science, two well-known denialist websites.

The quote provided at the link @263 is extracted from within the final paragraph of IPCC AR5 Section 5.3.5. Perhaps "quotes" would be a better description as the first half of the quote concerns NH while the final parts of the quote concerns the tropics. As provided at the link, these "quotes" don't make a lot of sense.

Medieval Warm Period was warmer

tmilliron at 12:45 PM on 22 September, 2019

This is fascinating work disputing MWP as localized instead of global https://kaltesonne.de/mapping-the-medieval-warm-period/

Medieval Warm Period was warmer

Daniel Bailey at 00:54 AM on 8 August, 2019

"I've seen mentions of growing grapes in Germany some 200m higher than before. Grapes in England. Etc. Seems a large effect for 1 degree."

Caution needs to be exercised when possibly over-interpreting local growing conditions experienced for periods of time less than a century. Extrapolating them to say anything about global conditions is usually a waste of time.

For example, while England had 42 vineyards at the time of the Domesday Book, as is well known, there are now nearly 400 commercial English vineyards today. So the climate today in England is much more conducive to wine-making than during the Roman occupation of England.

"It is generally agreed that the Romans introduced the vine to Britain. It has also been inferred that the climate in Britain at that time was warmer. At the end of the first century AD, however, the writer Tacitus declared that our climate was “objectionable”, and not at all suitable for growing vines.
Today, there are vineyards in nearly every county of England and Wales, and there are vines now planted in Scotland. Much of the acreage and vineyards lie in the southern part of England, and more specifically Kent, Sussex, Surrey and Hampshire. Those few hundred acres first planted has now grown to over 5,000. In the last ten years alone, the acreage planted has more than doubled, and nearly tripled since 2000. Last year, around 1 million vines were planted – the highest planting in a single year, and perhaps a higher volume is set to be planted in 2018. All of this will lead to some substantial increases in production."

LINK1

LINK2

By 1977, there were 124 reasonable-sized vineyards in production – more than at any other time over the previous millennium. The website of the English wine producers suggests that at present the extent of vineyards in Britain probably surpasses that of the Medieval Warm Period between circa 900 AD to 1300 AD.

Link
LINK3
LINK4

Be especially wary of those claiming the Vikings grew grapes in Greenland:

“Let me…assure you that the last wine plants to grow in Greenland were those that grew…60 million years ago.”

In 1982, Exxon accurately predicted global warming

Eclectic at 20:39 PM on 30 July, 2019

MsG @15 ,

If you seek some audiovisual presentations, then you may like the Youtube videos by Potholer54 (a science journalist by the name of Hadfield). Excerpts permissible, I'm sure !

Informative & often amusing & encouraging of critical thinking. The videos now number 50 (fifty!) but are mostly short (though some over 20 minutes).

Potholer54 avoids political partisanship, and is careful to give facts based on the scientific papers published in reputable peer-reviewed journals i.e. based on the actual science. Many of his videos are given with a humorous facet or two ~ which is (IMO) bound to appeal to you and your students.

Always , always , he emphasizes the importance of careful critical thinking wherever one encounters "facts" / information / hysteria / blogs / newspaper articles . . . and the need always to check the sources, find the original sources and evaluate their reliability, and be skeptical of the headlines.

# Be careful with the numerical label of each video ~ Youtube nowadays numbers the videos 1 - 50 , but the main video screen prominently displays an older numerical notation.

All are worth seeing (as fresh info for the climate science novice, and as humorous chuckles for the climate Old Hands . . . especially the five videos under the Monckton Bunkum heading ! )

If I may suggest a few :-

the 1st : "1- Climate Change - the scientific debate" [ 10 minutes]

the 23rd : "21- "Earth facing a mini-ice age!" [ 6 minutes]

the 25th : "23- Medieval Warm Period - fact vs. fiction" [ 20 minutes]

the 28th : "26- Science vs. the Feelies" [ 16 minutes]

the 29th : "27- The evidence for climate change WITHOUT computer models" [ 16 minutes]

the 31st : "28- The consequences of climate change (in our lifetimes)" [ 18 minutes]

the 40th : "A conservative solution to climate change - part 2" [ 21 min]

(The videos range in date from about 2009 'til 2019. None obsolete ! )

Climate's changed before

Daniel Bailey at 01:43 AM on 2 July, 2019

Here's those details and links on vineyards then vs now:

While England had 42 vineyards at the time of the Domesday Book, as is well known, there are now over 300 commercial English vineyards today. So the climate today in England is much more conducive to wine-making than during the Roman occupation of England.

http://www.english-wine.com/vineyards.html

"It is generally agreed that the Romans introduced the vine to Britain. It has also been inferred that the climate in Britain at that time was warmer. At the end of the first century AD, however, the writer Tacitus declared that our climate was “objectionable”, and not at all suitable for growing vines.
Today, there are vineyards in nearly every county of England and Wales, and there are vines now planted in Scotland. Much of the acreage and vineyards lie in the southern part of England, and more specifically Kent, Sussex, Surrey and Hampshire. Those few hundred acres first planted has now grown to over 5,000. In the last ten years alone, the acreage planted has more than doubled, and nearly tripled since 2000. Last year, around 1 million vines were planted – the highest planting in a single year, and perhaps a higher volume is set to be planted in 2018. All of this will lead to some substantial increases in production."

Emphasis and underlining added.

https://www.winegb.co.uk/visitors/background-info/history-of-the-industry/

By 1977, there were 124 reasonable-sized vineyards in production – more than at any other time over the previous millennium. The website of the English wine producers suggests that at present extent of vineyards in Britain probably surpasses that of the Medieval Warm Period between circa 900 AD to 1300 AD.

http://www.realclimate.org/index.php/archives/2006/07/medieval-warmth-and-english-wine/

New Scientist Link

Warmer now

https://www.eh-resources.org/historical-climatology/

In case anyone was wondering about Vikings and vineyards:

“Let me…assure you that the last wine plants to grow in Greenland were those that grew…60 million years ago.”

LINK

Humans are too insignificant to affect global climate

Eclectic at 18:43 PM on 29 June, 2019

Duke @31 ,

first go back to basics. The major factors determining the Earth's climate are :-

1. The insolation: level of shortwave energy coming from the sun.

2. The level of Greenhouse Gasses ~ most significantly, CO2.

3. The level of aerosol particles reflecting sunlight.

During the past almost 1 million years, the "Milankovitch cycle" of slight Earth axial & orbital changes has initiated/triggered a half-irregular series of glaciations & (briefer) de-glaciations. Currently we are on a gradual downward path of cooling (of about 5,000 years' duration) . . . and with more cooling still to come for 20 or so millennia. Or at least, that was the path, until recent events of the past 2 centuries. (Please note that the so-called Little Ice Age and the Medieval Warm Period have been fairly minimal wiggles on that long-term cooling background.)

However, against this background pattern of cooling, there has been an extraordinary (and continuing) upward spike of global temperature during the past 100 - 200 years. What has caused this remarkable change? #The analogy might be: a small-town police chief is used to seeing 3 - 6 house burglaries per year . . . but now he has just had 80 burglaries on one weekend ~ so, obviously, there's been a drastic change of some sort, and he has to figure out what has caused the extraordinary change.

For the scientists, they have to figure whether the rapid/huge temp spike ( currently about half a degreeC above the warmest level of the Holocene's previous 10,000 years ) has been caused by changes in insolation and/or GHGasses and/or aerosols. ( Other causes: cosmic rays, cloud changes, etcetera, have been checked out . . . and are clearly not a contributing factor in the climate change. )

Duke, you probably know most of that. And the evidence points to a single "culprit" for the spike. #Though I'm not sure what you mean by "dooming" ~ after all, the present & future consequences of global warming are 95% bad and 5% good (which is kind of okay for those in the 5% category!)

Planetary health and '12 years' to act

Daniel Bailey at 02:55 AM on 24 June, 2019

"ice core samples from Greenland show that over the last 10,000 years, the earth has been on average 3 degrees celcius warmer than today"

Global temperature reconstructions show this to be untrue.

Last 20,000 years

"how can anyone conclude this current round of warming is entirely manmade?"

Because actual scientists, using the well-understood physics of our world, have established that it is only when the anthropogenic forcing is included that the observed warming can be explained.

Natural vs Anthropogenic Climate Forcings, per the NCA4, Volume 2:

Forcings, NCA4

Fun Factoid: Changes in the sun's output falling on the Earth are about 0.05 Watts/meter squared.

By comparison, human activities warm the Earth by about 2.83 Watts/meter squared (AR5, WG1, Chapter 8, section 8.3.2, p. 676).

What this means is that the warming driven by the GHGs coming from the human burning of fossil fuels since 1750 is over 50 times greater than the slight extra warming coming from the Sun itself over that same time interval.

Radiative forcing 1750-2011

"What also troubles me is the fact that the Medieval Warm Period was written out of the history books by the IPCC hockey stick graph. As well the impact of the 500 year period of cooling known as the Little Ice Age"

Another meme. Here's the "Hockey Stick For The Most Recent 1,700 Years", from the Trump Administration in 2017:

Last 1,700 years

"the Earth was a lot warmer when the Vikings settled Greenland and Iceland"

Alreay refuted, but here's global temperatures with the period of the Viking occupation of Greenland highlighted:

Viking temps

And here's the temperatures from the GISP2 core from Greenland, with the instrumental temperature measurements taken from that same location added in for context:

Greenland last 10,000 years to 2017

"the Earth was a few degrees warmer during the Medieval Warm Period than it is today, then the polar ice cap was smaller and thinner than even now"

Your temperature claims were already refuted, but we have observational data to 1850 and proxy data going back millennia documenting Arctic sea ice extent changes over time.

For example, here's the last 1,500 years, from NOAA's Arctic Report card 2017:

Last 1,500 years in the Arctic

You'll need to raise your game to compete in this venue. In this venue, the onus is on YOU to be able to support your claims (each claim) with source citations, preferably to credible sources. Further, many of your claims are already refuted on separate posts here (thousands exist, use the Search function to find the most appropriate post to make your claims and to stake your reputation on).

I'm sure that the moderation staff would prefer to not intervene here, but I'm equally sure that they will if you continue to post what is essentially a Gish Gallop of memes refuted many times before (PRATT).

Read the Comments Policy and construct your comments to comply with it and my advice to you and all will be fine.

Planetary health and '12 years' to act

Philosopherkeys at 01:15 AM on 24 June, 2019

Being that the ice core samples from Greenland show that over the last 10,000 years, the earth has been on average 3 degrees celcius warmer than today, how can anyone conclude this current round of warming is entirely manmade? What also troubles me is the fact that the Medieval Warm Period was written out of the history books by the IPCC hockey stick graph. As well the impact of the 500 year period of cooling known as the Little Ice Age was not acknowledged by the hockey stick graph. Brian Fagan in his book, "The Little Ice Age" describes how glaciers in the European Alps or New Zealand in the Southern Hemisphere began growing once the earth began to cool. Entire villages and swaths of rainforest were obliterated by advancing glaciers. The hockey stick graph ignores the fact that the Earth was a lot warmer when the Vikings settled Greenland and Iceland. If as the ice core samples show, the Earth was a few degrees warmer during the Medieval Warm Period than it is today, then the polar ice cap was smaller and thinner than even now and quite possibly the alarm being sounded by certain climate scientists is uncalled for as this is a normal cycle that goes back and forth.

The Scientific Method

Eclectic at 05:44 AM on 13 June, 2019

TVC15 @58 , in view of comments elsewhere . . . it seems your adversarial friends are projecting themselves everywhere, most remarkably.

1. They should read the philosopher Popper ~ they have failed to understand the basic concept of Null Hypothesis. In view of the patently obvious sea level rise & ice melt, it is fair to say Global Warming now is the Null Hypothesis . . . and they themselves need to refute it.

2. The various methodologies of temp measurement are a strength, not a weakness.

3. It is statistically valid to use a variety of locations. (And scientist Nick Stokes has demonstrated the validity of using as few as as 61 sites worldwide.)

4. Data is often reviewed & adjusted quite openly, in order to reduce errors that are detected. That's the proper way of conducting science.

5. The global mean sea level is rising, and ice is melting, and plants & animals are changing their location as the temperature rises. All this is physical evidence of ongoing global warming. No "perception" is required.

6. The Little Ice Age and the Medieval Warm Period are both only very minor wiggles in average world temperature (and the 21st Century temperature is still rising and is distinctly above the MWP & the Holocene Maximum). The LIA and MWP are quite trivial and not in any way "inconvenient". How could anyone think them inconvenient ?

Apparently the plants & animals are more intelligent than your denialist "friends" ! ;-)

The Scientific Method

Daniel Bailey at 05:28 AM on 13 June, 2019

As a short answer, demand source citations (to credible sources) for each of those claims.

They won't furnish any because they don't have any.

That means no need to rebut each and every claim. If you feel like it, pick one and demolish it; an example:

"ignores "inconvenient" data points like the "Little Ice Age" and the "Medieval Warming Period" in data analysis"

The Little Ice Age and the Medieval Warming Period were not ignored. The Trump Administration placed them in their appropriate context, back in 2017:

Last 1,700 years

Advice: Don't play their game. Make them play yours.

The Scientific Method

TVC15 at 03:36 AM on 13 June, 2019

Hi Skeptical Science,

I'm dealing with some very difficult deniers and I was hoping to gain some insight on how to deal with such deniers.

This is what a denier I'm dealing with states over and over.

See the cornerstone of the scientific method and legitimate science- refuting the null hypothesis. AGW fails miserably in this regard and is thus not legitimate science.

AGW;

1. fails to refute the null hypothesis

2. compares temp data over time using four different temp measurements

3. fails to have consistent measuring locations over time

4. has intentionally altered or "adjusted" data to meet their hypothesis, rather than realizing the data refutes their hypothesis.

5. uses bogus statistical analysis to create the perception of warming

6. ignores "inconvenient" data points like the "Little Ice Age" and the "Medieval Warming Period" in data analysis.

AGW is bogus, junk science.

Medieval Warm Period was warmer

Eclectic at 16:03 PM on 12 June, 2019

RBF @250 , your "facts" sound a bit confused.

You are suggesting that the sealevel fell two feet over several centuries from the Medieval Warm Period until the depths of the Little Ice Age. Please cite your supporting source for your extraordinary statement ! (And over a total cooling of about half a degree Celsius ~ truly remarkable ! )

Medieval Warm Period was warmer

RBFOLLETT at 14:41 PM on 12 June, 2019

Wow, a hundred answers, but I think most of them missed the obvious. Everyone keeps focusing on the mythic global mean temperature that they say they can measure into the decimals (BS). They have been talking about sea level rise for the past 30 years almost within every sentence that contains the words global warming. So take a look at sea levels during the Medievil Warm Period then. Historical sea level charts show sea levels almost a foot higher than today and better yet actual History and living proof confirms historic Sea Ports miles inland from current sea shores. Actual physical empirical EVIDENCE that establishes sea levels much higher than today in the Medieval Warm Period, no science, no theory, no BS, just ABSOLUTE PROOF. The same goes for the the Mini Ice Age Cooling, sea level was down almost a foot from what it is today, again no BS, just Absolute Proof. Surely to God the Scientists are not now disputing the link between warming and sea level rise? What does it take to accept actual physical empirical evidence over scientific theory? Why go back tens of thousands of prehistoric years ago to predict what’s going to happen in the next hundred years, when you have historical evidence from the last 2000 years. Obvious cycles of warming and cooling are there in the sea level charts, a $10 tide gauge proves we have been warming for the last 250 years with another foot to go before we reach the levels of 450 years ago. Man (and the Polar Bears) have already survived a much warmer Earth, it’s a fact not a theory.

Humans and volcanoes caused nearly all of global heating in past 140 years

Eclectic at 07:24 AM on 1 June, 2019

Higgijh @post5 ,

If I have correctly understood your thoughts : your are basically concerned by the low time-resolution of past temperature (proxy) records & what may be inferred from them.

Certainly, the time-resolution becomes fuzzier, the farther back in time we explore. We can delineate the past 1000 - 2000 years of climate changes rather more exactly than the past 10,000 years or the 800,000 years (of the ice-core records) or the past 500 million years (with very low time-resolution in say the Ordovician period).

Yet the laws of physics haven't changed during all that time, and we can see [for example] that Newtonian Laws of Motion must have applied just as well during the Ordovician as during the current Holocene.

How does that apply to world temperature changes? If we look at the past 10,000 years (of the Holocene interglacial) we see a flat plateau of about 5,000 years [the "Optimum"] followed by the latest 5.000 years showing a gradual decline in temperature, which would eventually have triggered a new glaciation in about 20,000 or 30,000 years' time or more (an "abnormally" long interglacial, owing to the current low-ellipticity of Earth orbit). Or at least, that is what would happen, without the human [CO2] intervention of the past century or two.

The temperature record of recent centuries shows that the reaction to a major volcanic eruption is a very brief world temperature dip (less than 5 years). And the reaction to a major diminution of insolation (a Grand Solar Minimum) is a much more prolonged dip ~ but only about 0.3 degrees. These sorts of excursions explain why the "shape" of the Holocene resembles a relatively smooth plateau. The "wiggles" of temperature (such as the Medieval Warm Period or the Little Ice Age) are very minor indeed, against the general background.

Higgijh ~ going farther back in time, if you had been alive during the time of the Younger Dryas (and miraculously you lived for twice Methuselah's age! ) you would have seen a large excursion of world temperature during a 1000 years. But that change was gradual, compared with the rocket-like rise in temperature of the immediate 50 - 100 years past. And the cause of the Younger Dryas would have been very obvious to you (to you and your team of observer-scientists). The point being, that "low time-resolution" is not a problem in seeing the results of major climate factors.

Similarly, going back through 800,000 years, you see the climate alter in a cyclic way (Milankovitch insolation "forcing changes" of up to 0.7 watts/m2 , triggering a CO2 greenhouse change much larger than that). Again, the "smoothing" of the time-resolution record is not a problem for understanding the history.

For a separate additional effect to produce a rapid spike (up or down), there would have to be some large & powerful short-term causation for temperature change. Just as in Newtonian terms, a mass does not change velocity unless it is acted upon by a force ~ so too for climate : climate does not change unless something causes it to change.

Which is why - in the observed absence of major climate factor changes - it does not matter that the (proxy) climate record has a resolution far worse i.e. far fuzzier than annual / decadal / or centennial, as the case may be.

Higgijh, I hope I have addressed your basic concern. But perhaps you have deeper unexpressed concerns?

Humans and volcanoes caused nearly all of global heating in past 140 years

Eclectic at 20:41 PM on 31 May, 2019

Higgijh @post3 ,

(3) My apologies for fumbling your IPPC reference, but I turn up a completely inappropriate graph at Page 43. Would you be kind enough to insert your correct graph into the thread here? [Remembering the 500px width limit.] On second thoughts, it would be better for you to select a different thread ~ one where the question of Asian coal vs gas usage is on-topic (as it is not really relevant to the headline topic here of Humans and Volcanoes causing global heating since 1880 ).

(2) There is always the question of localization effects and time-resolution effects, in the assessing of temperature proxies in ice and sediments. But broadly speaking, these proxies are useful even when time-resolution is low.

We know that the climate only changes when something causes it to change ~ so in the absence of major factor changes in the last 10,000 years, we can [for example] be confident that the present-day world temperature is distinctly hotter than the Medieval Warm Period or the Roman Warm period or the "Holocene Optimum".

(1) Higgijh, this IPCC Page 43 seems the correct one you mean for (1). But I am entirely unclear on what difficulties you are having with it.

Climate trends are best assessed over a period of usually 30 years (or more) ~ so it is rather unsurprising that the Figure (c) over 60 years shows a good concordance between observations & models. Likewise it is not surprising that the short periods Fig. (a) 1998-2012 and Fig. (b) 1984-1998 , show observation/model disparity, since "natural internal variability" is more dominant during such very short periods.

The construction of climate models serves two purposes :-

# helping the assessment of individual climate factors [e.g. evapo-transpiration]

# projecting what may happen in the future, by a way which is likely to be much better than a guess ( = the equivalent of holding up a wetted finger to the breeze ).

The temperature evolution after 2016 suggests hotter future

Eclectic at 12:05 PM on 23 March, 2019

ThinkingMan , it's always worthwhile to step back occasionally and look at the bigger context.

Global surface temperature had been at a fairly flat plateau for (roughly) 5,000 years of the Holocene Maximum ~ which has been followed by (roughly) 5 or 6,000 years of gradual decline (related to the Milankovitch cycle of insolation). Owing to the present relatively-low ellipticity of the Earth's orbit, the next glacial phase is due in 20-30,000 years ~ and may be skipped altogether since the oceans are being unusually warmed by AGW.

The Little Ice Age, the Medieval Warm Period, the Roman Warm Period etcetera are only tiny wiggles in comparison to the multi-millennial decline in temperature.

Against this long-term decline, you can see the last (roughly) 100 years demonstrates a temperature rise which is shooting upwards like a rocket. And is now surpassing the Holocene Maximum. IMO it is beyond ridiculous for denialists to assert that our modern-day global warming is the result of a 60-year oscillation in oceanic currents.

Yet that is what some of the (more intelligent) denialists assert. No need to waste your time reading Professor Curry's blog ~ she is still suggesting that "up to" 60% of modern warming could be caused by confluence of oceanic current cycles. Quite marvellous it is, how a giant dose of "Motivated Reasoning" can so completely distort the rational thinking of an educated intelligent person.

You see rather similar bizarre thinking coming from Lindzen & Spencer & others. (And much of the remainder of denialists are still loudly proclaiming that CO2 has zero or negligible Greenhouse effect.)

2019 SkS Weekly Climate Change & Global Warming News Roundup #8

alonerock at 01:21 AM on 25 February, 2019

Hi All-

Please comment on Moore's text below so that I can refute his opinions with facts in an argument I am having with a friend about its content:

Patrick Moore Comments to refute/clarify:
CO2 lags temperature by an average of 800 years during the most recent 400,000-year period, indicating that temperature is the cause, as the cause never comes after the effect.
Looking at the past 50,000 years of temperature and CO2 we can see that changes in CO2 follow changes in temperature. This is as one could expect, as the Milankovitch cycles are far more likely to cause a change in temperature than a change in CO2. And a change in the temperature is far more likely to cause a change in CO2 due to outgassing of CO2 from the oceans during warmer times and an ingassing (absorption) of CO2 during colder periods. Yet climate alarmists persist in insisting that CO2 is causing the change in temperature, despite the illogical nature of that assertion.
. Will our CO2 emissions stave off another glaciation as James Lovelock has suggested? There doesn’t seem to be much hope of that so far, as despite 1/3 of all our CO2 emissions being released during the past 18 years the UK Met Office contends there has been no statistically significant warming during this century.
By 7,000 years ago all the low-altitude, mid-latitude glaciers had melted. There is no consensus about the variation in sea level since then although many scientists have concluded that the sea level was higher than today during the Holocene Thermal optimum from 9,000 to 5,000 years ago when the Sahara was green. The sea level may also have been higher than today during the Medieval Warm Period.
Coming back to the relationship between temperature and CO2 in the modern era we can see that temperature has risen at a steady slow rate in Central England since 1700 while human CO2 emissions were not relevant until 1850 and then began an exponential rise after 1950. This is not indicative of a direct causal relationship between the two. After freezing over regularly during the Little Ice Age the River Thames froze for the last time in 1814, as the Earth moved into what might be called the Modern Warm Period.
The IPCC states it is “extremely likely” that human emissions have been the dominant cause of global warming “since the mid-20th century”, that is since 1950. They claim that “extremely” means 95% certain, even though the number 95 was simply plucked from the air like an act of magic. And “likely” is not a scientific word but rather indicative of a judgment, another word for an opinion.
There was a 30-year period of warming from 1910-1940, then a cooling from 1940 to 1970, just as CO2 emissions began to rise exponentially, and then a 30-year warming from 1970-2000 that was very similar in duration and temperature rise to the rise from 1910-1940. One may then ask “what caused the increase in temperature from 1910-1940 if it was not human emissions? And if it was natural factors how do we know that the same natural factors were not responsible for the rise between 1970-2000.” You don’t need to go back millions of years to find the logical fallacy in the IPCC’s certainty that we are the villains in the piece.
Water is by far the most important greenhouse gas, and is the only molecule that is present in the atmosphere in all three states, gas, liquid, and solid. As a gas, water vapour is a greenhouse gas, but as a liquid and solid it is not. As a liquid water forms clouds, which send solar radiation back into space during the day and hold heat in at night. There is no possibility that computer models can predict the net effect of atmospheric water in a higher CO2 atmosphere. Yet warmists postulate that higher CO2 will result in positive feedback from water, thus magnifying the effect of CO2 alone by 2-3 times. Other scientists believe that water may have a neutral or negative feedback on CO2. The observational evidence from the early years of this century tends to reinforce the latter hypothesis.
Even at the today’s concentration of 400 ppm plants are relatively starved for nutrition. The optimum level of CO2 for plant growth is about 5 times higher, 2000 ppm, yet the alarmists warn it is already too high.
All the CO2 in the atmosphere has been created by outgassing from the Earth’s core during massive volcanic eruptions. This was much more prevalent in the early history of the Earth when the core was hotter than it is today. During the past 150 million years there has not been enough addition of CO2 to the atmosphere to offset the gradual losses due to burial in sediments.
Today, at just over 400 ppm, there are 850 billion tons of carbon as CO2 in the atmosphere. By comparison, when modern life-forms evolved over 500 million years ago there was nearly 15,000 billion tons of carbon in the atmosphere, 17 times today’s level. Plants and soils combined contain more than 2,000 billion tons of carbon, more that twice as much as the entire global atmosphere. The oceans contain 38,000 billion tons of carbon, as dissolved CO2, 45 times as much as in the atmosphere. Fossil fuels, which are made from plants that pulled CO2 from the atmosphere account for 5,000 – 10,000 billion tons of carbon, 6 – 12 times as much carbon as is in the atmosphere.
But the truly stunning number is the amount of carbon that has been sequestered from the atmosphere and turned into carbonaceous rocks. 100,000,000 billion tons, that’s one quadrillion tons of carbon, have been turned into stone by marine species that learned to make armour-plating for themselves by combining calcium and carbon into calcium carbonate. Limestone, chalk, and marble are all of life origin and amount to 99.9% of all the carbon ever present in the global atmosphere. The white cliffs of Dover are made of the calcium carbonate skeletons of coccolithophores, tiny marine phytoplankton.
The vast majority of the carbon dioxide that originated in the atmosphere has been sequestered and stored quite permanently in carbonaceous rocks where it cannot be used as food by plants.
Beginning 540 million years ago at the beginning of the Cambrian Period many marine species of invertebrates evolved the ability to control calcification and to build armour plating to protect their soft bodies. Shellfish such as clams and snails, corals, coccolithofores (phytoplankton) and foraminifera (zooplankton) began to combine carbon dioxide with calcium and thus to remove carbon from the life cycle as the shells sank into sediments; 100,000,000 billion tons of carbonaceous sediment. It is ironic that life itself, by devising a protective suit of armour, determined its own eventual demise by continuously removing CO2 from the atmosphere. This is carbon sequestration and storage writ large. These are the carbonaceous sediments that form the shale deposits from which we are fracking gas and oil today. And I add my support to those who say, “OK UK, get fracking”.
The past 150 million years has seen a steady drawing down of CO2 from the atmosphere. There are many components to this but what matters is the net effect, a removal on average of 37,000 tons of carbon from the atmosphere every year for 150 million years. The amount of CO2 in the atmosphere was reduced by about 90% during this period. This means that volcanic emissions of CO2 have been outweighed by the loss of carbon to calcium carbonate sediments on a multi-million year basis.
If this trend continues CO2 will inevitably fall to levels that threaten the survival of plants, which require a minimum of 150 ppm to survive. If plants die all the animals, insects, and other invertebrates that depend on plants for their survival will also die.
How long will it be at the present level of CO2 depletion until most or all of life on Earth is threatened with extinction by lack of CO2 in the atmosphere?
During this Pleistocene Ice Age, CO2 tends to reach a minimum level when the successive glaciations reach their peak. During the last glaciation, which peaked 18,000 years ago, CO2 bottomed out at 180 ppm, extremely likely the lowest level CO2 has been in the history of the Earth. This is only 30 ppm above the level that plants begin to die. Paleontological research has demonstrated that even at 180 ppm there was a severe restriction of growth as plants began to starve. With the onset of the warmer interglacial period CO2 rebounded to 280 ppm. But even today, with human emissions causing CO2 to reach 400 ppm plants are still restricted in their growth rate, which would be much higher if CO2 were at 1000-2000 ppm.
Here is the shocking news. If humans had not begun to unlock some of the carbon stored as fossil fuels, all of which had been in the atmosphere as CO2 before sequestration by plants and animals, life on Earth would have soon been starved of this essential nutrient and would begin to die. Given the present trends of glaciations and interglacial periods this would likely have occurred less than 2 million years from today, a blink in nature’s eye, 0.05% of the 3.5 billion-year history of life.
No other species could have accomplished the task of putting some of the carbon back into the atmosphere that was taken out and locked in the Earth’s crust by plants and animals over the millennia.
It does boggle the mind in the face of our knowledge that the level of CO2 has
been steadily falling that human CO2 emissions are not universally acclaimed as a miracle of salvation. From direct observation we already know that the extreme predictions of CO2’s impact on global temperature are highly unlikely given that about one-third of all our CO2 emissions have been discharged during the past 18 years and there has been no statistically significant warming. And even if there were some additional warming that would surely be preferable to the
analysis of the historical record and the prediction of CO2 starvation based on the 150 million year trend. Ad hominem arguments about “deniers” need not apply. I submit that much of society has been collectively misled into believing that global CO2 and temperature are too high when the opposite is true for both. Does anyone deny that below 150 ppm CO2 that plants will die? Does anyone deny that the Earth has been in a 50 million-year cooling period and that this Pleistocene Ice Age is one of the coldest periods in the history of the planet?
If we assume human emissions have to date added some 200 billion tons of CO2 to the atmosphere, even if we ceased using fossil fuels today we have already bought another 5 million years for life on earth. But we will not stop using fossil fuels to power our civilization so it is likely that we can forestall plant starvation for lack of CO2 by at least 65 million years. Even when the fossil fuels have become scarce we have the quadrillion tons of carbon in carbonaceous rocks, which we can transform into lime and CO2 for the manufacture of cement. And we already know how to do that with solar energy or nuclear energy. This alone, regardless of fossil fuel consumption, will more than offset the loss of CO2 due to calcium carbonate burial in marine sediments. Without a doubt the human species has made it possible to prolong the survival of life on Earth for more than 100 million years. We are not the enemy of nature but its salvation.

Some of the world’s oil comes from my native country in the Canadian oil sands of northern Alberta. I had never worked with fossil fuel interests until I became incensed with the lies being spread about my country’s oil production in the capitals of our allies around the world. I visited the oil sands operations to find out for myself what was happening there.
It is true it’s not a pretty sight when the land is stripped bare to get at the sand so the oil can be removed from it. Canada is actually cleaning up the biggest natural oil spill in history, and making a profit from it. The oil was brought to the surface when the Rocky Mountains were thrust up by the colliding Pacific Plate. When the sand is returned back to the land 99% of the so-called “toxic oil” has been removed from it.
Anti-oil activists say the oil-sands operations are destroying the boreal forest of Canada. Canada’s boreal forest accounts for 10% of all the world’s forests and the oil-sands area is like a pimple on an elephant by comparison. By law, every square inch of land disturbed by oil-sands extraction must be returned to native boreal forest. When will cities like London, Brussels, and New York that have laid waste to the natural environment be returned to their native ecosystems?
The art and science of ecological restoration, or reclamation as it is called in the mining industry, is a well-established practice. The land is re-contoured, the original soil is put back, and native species of plants and trees are established. It is possible, by creating depressions where the land was flat, to increase biodiversity by making ponds and lakes where wetland plants, insects, and waterfowl can become established in the reclaimed landscape.
The tailings ponds where the cleaned sand is returned look ugly for a few years but are eventually reclaimed into grasslands. The Fort McKay First Nation is under contract to manage a herd of bison on a reclaimed tailings pond. Every tailings pond will be reclaimed in a similar manner when operations have been completed.

Climate Carbon Bookkeeping

Daniel Bailey at 07:52 AM on 17 January, 2019

"And, although looking at the past 2,000 years, we see several warming periods (Roman, Medieval), overall, cooling occurred at an even faster rate. Significantly, the last 700 years, which includes the historically colder Little Ice Age (LIA), brought even faster cooling and then warming coming out of the LIA into the Modern Late 20th-Century Warm Period"

Let's look at the global temperatures reconstructed from proxies over that interval:

"Scientists have concluded that over the last 10,000 years, the temp is relatively flat...The graph was created based on Greenland ice core data by the late paleoclimatologist, Professor Bob Carter"

Why would you think that a temperature reconstruction from Greenland, a regional-to-local record, would have any meaning for the rest of the globe?

Let's look at the global temperatures reconstructed from proxies over the past 20,000 years, for context:

For fun, here's the same over the past 800,000 years:

For more on Bob Carter, see here.

Climate Carbon Bookkeeping

Dan Joppich at 05:31 AM on 17 January, 2019

Thanks. This is very cool stuff. I haven't had a chance to read it thoughtfully due to my day job demands but I was curious about how this graph plotting temp data since the last glacial period (sorry, I couldn't figure out how to insert it here) . Scientists have concluded that over the last 10,000 years, the temp is relatively flat. Here's the link:

https://commons.wikimedia.org/wiki/File:Holocene_Temperature_Variations.png

The graph was created based on Greenland ice core data by the late paleoclimatologist, Professor Bob Carter.

It seems that over the past 10,000 years, we've seen warming and cooling oscillate within a range of +/- 2.5 degrees Celsius (D.C.). The rate today using satellite data (if you're familiar with Anthony Watts's other website, you know that nothing else will do) is 1.5 D.C./century, which is right within the Holocene averages.

And, although looking at the past 2,000 years, we see several warming periods (Roman, Medieval), overall, cooling occurred at an even faster rate. Significantly, the last 700 years, which includes the historically colder Little Ice Age (LIA), brought even faster cooling and then warming coming out of the LIA into the Modern Late 20th-Century Warm Period.

Of course, this data needs to be superimposed onto the CO2 data to be truly comparable to the conversation here, but it does narrow down our range to a possibly more relevant period in human history.

But their Emails!

nigelj at 10:27 AM on 1 December, 2018

JP66, the email you quote is a single email relating to climategate taken completely out of context, which shows the whole problem with these thefts / hacks. It's hard to even know what they are really saying, other than they appear to be arguing whether a paleo climate reconstruction of the medieval warm period is reliable, notice its in reference to "a" reconstruction.

I don't see what "theory" this undermines. Greenhouse gas theory, human impacts on climate,and future modelling of temperatures obviously do not rely on reconstructions of the medieval warm period.

What theory do you claim it undermines? What is it you think they are really saying?

Yes they are also talking about problems they are having with analysing the past, misakes that might have ocassionally been made, people attacking their work and how they should respond to this. Wouldn't any normal person do this? Why do you think this is somehow nefarious or abnormal?

If this is the so called smoking gun in climategate its laughable.

I do agree with you if the latest data and the accepted theory diverge then question the theory, but this is not apparent in this case. Also question whether the data is reliable, as it often turns out the data is wrong, for example the problems where the satellite temperature record originally showed a cooling, when it turned out there were problems with the satellite sensors or something.

Please note that many groups have analysed the MWP and found it was no warmer than temperatures over the last decade.

Climate science comeback strategies: Al Gore said what?

Eclectic at 09:41 AM on 28 November, 2018

JP66 @11 ,

A/ Yes you are quite right, we should assess things coolly and logically, and not be swept away by a few tiny pieces of evidence (like cherry-picking a handful of leaves from a large forest). There is a vast wealth of evidence ~ consilient evidence ~ supporting the mainstream climate science . . . and there is almost none supporting the "denialist" viewpoint. The denialists have rhetoric, and not much else.

B/ As you are already aware, I'm sure, the hugely significant difference between the previous changes in temperature during the Holocene, and the present day global temperature . . . is that of rate of change. At present, the surface temperature is climbing vertically like a Hornet on afterburners (excuse the mild hyperbole!). And it is still climbing rapidly. This is a vastly different situation from the slow & slight changes during the so-called Holocene Optimum and during the 5,000 years since then.

C/ It's a good idea to step back and look at the bigger picture. Coming out of the last glacial stage (and speaking in broad terms) there was a 10,000-year gradual rise of temperature of roughly 5 degreesC (and there was also a 1,000-year wiggle in the middle of that, named the Younger Dryas). Then came a rather flat period of about 5,000 years, which some call the Holocene Optimum. Following that, for 5,000 years has been a slow fall of temperature . . . until now. Just as seen in the level Holocene Optimum, we also see during the declining past 5,000 years ~ various minor bumps and minor troughs (named the Roman Warm Period, the Medieval, the Little Ice Age, etcetera etcetera). These small wiggles are very small, and came and went slowly (and they are so small in amplitude of rise/fall, that is is difficult to exactly define their start and finish).

D/ The more important point is : what caused these previous minor wiggles during the Holocene? There's only a limited number of candidates ~ minor variations in solar output (on a multi-decadal scale); occasional major volcanic activity; long-cycle oceanic overturning currents; etcetera. Climate changes when something causes it to change. It doesn't change for no reason. (And I am sure you also know of the ultra-long cycle of Milankovitch.). This is why the denialists are talking arrant nonsense, when they say that the recent warming [say from 1800 or 1850] is just "a rebound from the Little Ice Age" ~ they seem to forget that there must be an actual cause for change.

JP66 . . . against the overall picture, the overall evidence . . . it is very difficult to find anything to get excited about, in fjord depths. (If I have mis-read that, then I would be grateful if you would explain the significance.)

JP66 , if you wish to question the general world data being correct/incorrect ~ you should read & discuss at a more appropriate thread. [And a Spoiler Alert : the denialists have got that wrong as well!]

Climate science comeback strategies: Al Gore said what?

JP66 at 07:36 AM on 28 November, 2018

I am a climate fence sitter. I like to think I read diligently on all sides. Recently I came across a paper listed on a "denier" site and was wondering what the folks here had to say. The conclusion of the study was quite clear:

"The record shows a substantial and long-term warming during the Roman Warm Period (~350 BCE – 450 CE), followed by variable bottom water temperatures during the Dark Ages (~450 – 850 CE). The Viking Age/Medieval Climate Anomaly (~850 – 1350 CE) is also indicated by positive bottom water temperature anomalies, while the Little Ice Age (~1350 – 1850CE) is characterized by a long-term cooling with distinct multidecadal variability. When studying the Gullmar Fjord bottom
water temperature record for the last 2500 years, it is interesting to note that the most recent warming of the 20th century does
not stand out but appears to be comparable to both the Roman Warm Period and the MCA."

Tracing winter temperatures over the last two millennia using a NE
Atlantic coastal record
Irina Polovodova Asteman1
, Helena L. Filipsson 2
, Kjell Nordberg 1 5
1 Department of Marine Sciences, University of Gothenburg, Carl Skottbergsgata 22B, 41319 Gothenburg, Sweden
2 Department of Geology, University of Lund, Sölvegatan 12, 22362 Lund, Sweden

https://www.clim-past-discuss.net/cp-2017-160/cp-2017-160.pdf

I realize the first and foremost rebuttal would be to say the report covers a subset of the globe and not the whole, but similar such studies show the same result in many areas of the globe. Is the data incorrect? Why are global average anomalies better suited to determining whether there is warming?

Thank you for your input.

Joe in NY

2018 SkS Weekly Climate Change & Global Warming News Roundup #42

ubrew12 at 05:07 AM on 21 October, 2018

I enjoyed and call attention to 'How A Viking Swimming With A Sheep Led To Climate Change Denial'. It's a powerful reminder of how people who desperately wish something to be true (in this case, the Medieval Warm Period) will inflate any possible evidence into a 'proof'. Apparently, it was recorded that in the 10th century, a Greenland Viking swam to a neighbor island to get a sheep, then swam back. Clearly, the World was quite warm back then, because Greenland is the World. Also, a 10th century book of Viking lore, which includes accounts of mermen giving prophecies, and witches luring fish into their baskets, should be taken literally as a serious account of Viking history.

Increasing CO2 has little to no effect

scaddenp at 11:44 AM on 10 July, 2018

jesscars - I explained why you cant do it with a plastic bag - it is not 55km high. You cant complain about science being wrong when the problem is with your understanding of it. You do not appear to have looked at resources posters have offered you.

You have now raised a whole bunch of long-debunked talking points which are offtopic here. Please use the search button on top left or the "arguments" to find the appropriate myth and comment there, not here.

eg "Climate has changed before", "Co2 lags temperature". It would seem that with a very large no. of misunderstandings about climate, that a read through the appropriate section the IPCC WG1 to get a grip on the basics. I would also reiterate the Science of Doom. Just for starters, the ice-age cycle is driven by orbital variation which primarily affect earths albedo. Once temperatures change, CO2 changes also from interactions with ocean and eurasian wetlands amplifying the effect. The detail here is huge - if you want to question the science, then please become familiar with the science first.

Melting Arctic sends a message: Climate change is here in a big way

nigelj at 18:48 PM on 1 June, 2018

Billev #6, Greenland has been farmed for centuries and still is now.

en.wikipedia.org/wiki/Economy_of_Greenland#Agriculture_and_forestry

"We appear to be experiencing the same sort of climate change that humans have previously experienced;"

Climate change is quite different now. Reconstructions show temperatures over the last decade are higher than during the medieval warm period and in fact higher than the last 10,000 years. The recent warming is driven primarily by greenhouse gases, solar activity has been falling slightly for the last 50 years, and the specific way the earth is heating can only be explained by the greenhouse effect.

I think you know this, and this is why your comments are so lame. You obviously have no real enthusiasm for your own beliefs, and certainly have no evidence to back them up.

The Debunking Handbook Part 4: The Worldview Backfire Effect

RightThou1 at 06:01 AM on 1 May, 2018

We are dealing with worldview bias rather than debating in a scientific framework, for the most part we are talking to global warming deniers, who deny they are deniers for the most part. Really I am surprised if any single global warming denier ever changes their mind.

They have been denying they are deniers, what do you think of the idea of using that against them. When you ask "is global warming real", they have sometimes shifted from answering "no", to answer "yes but".

Am I right in thinking that when someone agrees with you in an argument, you should rub it in? For example I know that when they say "yes but", that what is to follow is an explanation, "yes but it isn't caused by man, might be beneficial, is the same thing as the medieval period, etc". But for all that talk, as frustrating as it is, when they say "yes but", haven't they essentially said "you are right, but ..."? So that, I could rub that in.

For example, a politician from a particular political party which admits global warming is real like the rest of the world, could ask a politician from another political party which bitterly opposes any recognition of the reality of global warming, over and over: "I understand that you have admitted global warming is real, I really admire that". In response, "yes but (with long explanation)".

Because, I think the tactic of saying I admit global warming is real but here is my long explanation in which I try to have everything both ways and merely sow doubt and stall. It seems like a clever tactic and it is infuriating, but maybe it can be another liability for them.

2018 SkS Weekly Climate Change & Global Warming News Roundup #16

nigelj at 07:20 AM on 24 April, 2018

Other studies of MWP hockey sticks here.

There's no empirical evidence

Eclectic at 00:35 AM on 5 February, 2018

Funkymystic @355 , alas nobody can help you make sense of Gregg Braden's explanation of the graph he shows in his video.

That's because Gregg Braden's ideas are way beyond California Crackpot.

The average climate-denialist grudgingly admits [well, most days of the week] that at least some of the modern rapid global warming is caused by higher level of CO2 in the atmosphere. But Braden is on another planet — he (in his video) claims that as CO2 goes up, it causes temperature to go down. That the CO2 causes cooling !! Marvellous how he can suggest that concept, while keeping a straight face.

Braden's past history also includes other beyond-crazy ideas. Which he tries to flesh out by displaying actual genuine scientific graphs . . . which he fails to interpret in a sane scientific way.

For instance, the ice-core temperature/CO2 charts he displays, are stated by him to apply to the whole Earth's climate, rather than just the local regions from which the cores were taken. Hence his nonsense about the so-called Medieval Warm Period (MWP) being hotter than today's worldwide climate. And he is obsessed by "natural cycles" (which cannot explain the recent rocketing planetary temperature). He gazes at cycles (whether regular or irregular, whether Milankovitch-related or not) and he seems oblivious to the basic physical fact that changes in planetary climate must be caused by actual physical effects — they don't just happen because "it's time for them to happen".

Funkymystic, please have good read through Climate Myth Number 12 "CO2 Lags Temperature" [which you will find via the Home Page here, top left portion]. That will explain the complex feedback link between global atmospheric CO2 and the advance & recession of "ice ages" & interglacials. You will soon see how Braden has made a colossal error in understanding things. Doubtless Mr Braden has had these things pointed out to him on various occasions — but it seems he is not interested in scientific truth.

Fake news is a threat to humanity, but scientists may have a solution

nigelj at 05:07 AM on 31 December, 2017

Zippi62 @23

"Climate science doesn't base their findings on Michael Mann's "Hockey Stick Graph". Do they?"

No they dont, because it was only one early study and of average quality. The IPCC reports mostly do not to rely on single isolated studies, because that would obviously be sub optimal. I would have my doubts myself.

The IPCC rely on multiple studies whenever they can, and this is why a lot of research is done, like double entry book keeping in accounting it helps identify errors in research and improve research.

We have about 10 other more recent and thorough studies on the medieval warm period, that find very similar results and similar shaped hockey stricks to Manns original study, for example by Briffa, Esper and many others. Refer medieval warm period on wikipedia for lists of published research. The studies all take different approaches to researching the issues.

You think this is some giant conspiracy? If so,that is where we part company completely and irrevocably. I live in the real world (which is hard enough) not the Brietbart fantasy world.

The moral and intellectual bankruptcy of the Republican Party

nigelj at 11:05 AM on 6 December, 2017

Villabaloo @15, interesting that you mention Rush Limbaugh. We have our own equivalent in NZ, a guy called Leighton Smith. Fortunately he announced just a day ago that is retiring next year. Yay! I think hate merchant sums up their style.

Everyday his talk back radio is the same garbage: climate change is allegedly a "scam", what about the medieval warm period?, we are coming out of the little ice age, there is no consesus and so on, ad nauseum. No matter how many times you point out the huge holes in these arguments, you just get brushed off or called names or are labelled a pc leftist. Its ironic becuase my politics are so middle ground overall, that if I gave a lecture on politics and economics, it would probably send people to sleep.

These denialists are often just dummies, but the ones who worry me are the intelligent ones that are driven by politics, and very manipulative of public opinion. And Smith is not totally unintelligent.

Then you get lectured by Mr Smith about how everything is "too pc" or a "socialist conspiracy" and how multiculturalism is evil, taxation is theft, etc, etc in a constant stream of angry ranting and believe me this guy gets angry, maybe partly to attract attention to get ratings, and partly because he is naturally angry. He swears on radio sometimes (while complaining about the language of the younger generation).

Does that all sound like RL?

Medieval Warm Period was warmer

John Hartz at 00:27 AM on 14 September, 2017

Norris M @247: You state,

My take on all of this is that no one is denying that there clearly was a MWP which, given the droughts in the SW US and the recent Chinese Academy of Sciences report on a MWP in China, suggests that this was probably prevalent in most of the Northern Hemisphere.

Your tentative conclusion about the MWP being prevelant in the Northen Hemisphere is not supported by the research documented in the following articles:

So-Called Medieval Warm Period Not So Warm After All by Michael D Lemonick, Climate Central, Oct 1, 2012

Study undercuts idea that 'Medieval Warm Period' was global: Vikings may not have colonized Greenland in nice weather, Science Daily, Dec 4, 2015

Climate's changed before

John Hartz at 23:13 PM on 11 September, 2017

NorrisM, Electric & Michael Sweet:

Please take any further discussion of the Medieval Warm Period to the thread of the SkS Rebuttal aricle, How does the Medieval Warm Period compare to current global temperatures?

Climate's changed before

John Hartz at 09:23 AM on 11 September, 2017

NorrisM & Michael Sweet:

Please take any further discussion of the Medieval Warm Period to the thread of the SkS Rebuttal aricle, How does the Medieval Warm Period compare to current global temperatures?

The Trump administration wants to bail out failed contrarian climate scientists

Jeff B at 08:03 AM on 4 September, 2017

I hope that I am not too late to this discussion to make a comment.

First, in my view, this request for a "Red Team/Blue Team" exercise is not originating from the politicians of the Republican Party. It is instead originating from the donor class of the Republican Party, which is composed primarily of very wealthy and politically active Free Market/Libertarians. For those who follow US politics, it became apparent in about 2008-2010 time frame that Republicans abruptly went from a party that was willing to discuss (albeit not take action) on global warming to one where even discussion was considered off-limits. With the "Citizens United" Supreme Court decision in 2010, the ability for dark money to influence campaigns allowed the Free Market/Libertarian donor class to enter into the political process early in campaigns with substantial financial resources when it is very important for candidates. The choice was given to candidates of either to agree to the dogma of the donor class or face a well-funded primary opponent. In my view, this is the reason why trying to change Republican policy through evidence or grass roots lobbying is bound to fail. It is not the Republican politicians that need convincing, it is the Republican donor class that needs convincing.

Second, strategically the Free Market/Libertarians deniers/luke-warmers have placed advocates for action on global warming in a difficult position. For if one says "no" that we won't participate in a "Red Team/Blue Team" exercise then it is easy to state the "Of course, they are hiding something because they don't want to have an open debate". So even though it makes absolutely no sense to have such an exercise from a "this is how science works" perspective, it is really important to have the exercise from a political/convincing the public perspective.

Another point, the "Red Team/Blue Team" exercise could be looked at an important means to educate everyone as to the basics of global warming science. The US media just does a lousy job of keeping this issue in the limelight and as a consequence the American populace is just going to respond not based on rational evaluation but according to their tribal affiliation. This exercise could be immensely successful if climate scientists would use this as an opportunity to communicate very basic scientific concepts to the greater populace. For example, the concept of thermal inertia is just not communicated at all. Neither is the concept of thermal expansion of the oceans and the non-uniform increase in sea temperatures contributing to sea level rise. And I rarely hear anyone talk about how night time low temperatures should be considered a finger print of global warming.

The key to making it successful though is to frame the discussion very narrowly to the key issues as hand. I have watched enough congressional testimony and read enough Wall Street Journal opinions to see how debate is side-tracked by red-herring arguments, such as the existence of the Medieval Warming Period or the 17-year "pause". The purpose of a "Red Team/Blue Team" excercise should be to remove "doubt" so it would be imperative to structure the discussion so that non-germane points which serve only to sow confusion are off-limits.

The Trump administration wants to bail out failed contrarian climate scientists

NorrisM at 16:47 PM on 3 September, 2017

JW Rebel @ 19

I do not want to make a big deal of this but there is an underlying assumption you make. You assume that because one group may citicize the explanation of some theory that it is not acceptable to criticize that theory without coming up with an alternative theory. You are 100% wrong in that assumption.

It is perfectly acceptable to criticize a theory without coming up with an alternative. One may question the existence of God (for lack of evidence) without coming up with an alternative explanation of why we are here.

In the area of climate change, it is perfectly acceptable to criticize the existing theories without coming up with an alternative explanation. In science, it perfectly acceptable to simply say, this theory is wrong but we just do not know what the answer is. You do not have to come up with a viable alternative.

At this point in my personal deliberations, I am convinced that man has caused the temperature to increase because of CO2 emissions but I am not convinced that the models can accurately predict what the effects will be over the next 70 years or beyond. What troubles me is that these computer models have to make massive assumptions about the impact of clouds because they simply do not have the computer power to properly build them into the models. I think the term they use is "parameterizations". Another issue is how sensitive the climate is to the massive increases in CO2, namely, how much in "positive feedbacks" are created by water vapour, etc.. I would like to hear from both sides on this issue. I would also like to hear from both sides how successful the models have been in predicting temperatures since the models have been developed. I read Michael Mann's support for the James Hansen predictions in an recent article in Foreign Affairs but it seems to me that he "cherry picked" his predictions. Many of Hansen's predictions as to temperature increased in the last 20 yeas were quite far off which were not referenced.

I would also like to hear whether the experts agree on whether there really was a Medieval Warming Period and a Little Ice Age. According to Michael Mann there was no such thing in the promotion of this "hockey stick" which was to show that the temperature increase today is unprecedented in the last 2000 years. A recent Chinese study has shown that certainly in China there have been periods of warming corresponding to the MWP and periods of cooling corresponding to the Little Ice Age. This corresponds to the information we have both about Greenland and Europe.

I am not saying that proving there was a MWP or a Little Ice Age means that we do not have a problem today but I would just like to get the facts and I am not convinced Michael Mann et al have delivered same. I have to admit that Climategate seriously impacted my trust of Michael Mann and Phil Jones. I do not care that their respective universities "cleared" them of any wrongdoing. You have to have massive blinders on you not to read these emails and wince. Are they scientists or are they going beyond the science to promote what they think is the "right thing to do"?

Returning to your main point, it may very well be that there are so many factors involved that it is impossible to predict what the climate will do in 30, 70 or more years. And it may be impossible to predict what portion of today's temperature increase is attributable to anthropogenic influences. This does not end the argument. We clearly have polar ice caps and glaciers melting. Oceans are rising (although they have been for 150 years).

So it behooves us to consider what we should do.

I just had to comment on your premise that the "other side" has to come up with a viable explanation otherwise you just accept the present premise and predictions of future temperature increases and the concomitant effects.

So I am hoping that a red team blue team can deal with some of these issues. I do not have any preconceived views on what would be achieved but I would enjoy seeing each side go at each other.

For those who say that it is too complicated, I say "fooey". If you cannot hit the main points and come to a conclusion then we should not be going down the road of massive changes to our society because it is undemocratic. If you cannot distil these issues for the public and you therefore have to rely on arguments of "trust me" or "trust the IPCC" then I do not think you have a chance at all of convincing the majority of the US public to go along with the massive changes proposed. Gradually switching to RE, yes, but not massive changes which impact their economic well being. It is like asking the Oracle of Delphi to tell the ruler whether he should go to battle. I think we have got beyond that stage.

Medieval Warm Period was warmer

J Doug Swallow at 02:11 AM on 10 August, 2017

From recent experience on this site and dealing with this topic "How does the Medieval Warm Period compare to current global temperatures?" I'm sure that neither Daniel Bailey & doug_bostrom will believe that this information below pertains to the Medieval Warm Period and, if not, they should tell me why it does not.

Since Michael Mann felt that he could get away with using falsified tree ring observations from two trees in Siberia to make his hockey stick graph when pollen records show something very different.
Widespread evidence of 1500 yr climate variability in North America during the past 14 000 yr
Abstract: "Times of major transitions identified in pollen records occurred at 600, 1650, 2850, 4030, 6700, 8100, 10 190, 12 900, and 13 800 cal yr B.P., consistent with ice and marine records. We suggest that North Atlantic millennial-scale climate variability is associated with rearrangements of the atmospheric circulation with far-reaching influences on the climate."
<http://geology.geoscienceworld.org/cgi/content/abstract/30/5/455>

Climate Change Froze the Vikings Out of Greenland, Say Scientists

''What’s the News: Climate change may have sparked the demise of early Viking settlements in Greenland, according to a new study published online in the Proceedings of the National Academy of Sciences, when temperatures cooled rapidly over several decades. Around the time the Vikings disappear from the island’s archaeological record, temperature appears to have plunged. Nor were the Vikings the only people in Greenland whose fortunes rose and fell with the average temperature, the study suggests. Earlier cold spells may have played a role in the collapse of two previous groups on the island.''

<http://blogs.discovermagazine.com/80beats/2011/05/31/climate-change-froze-the-vikings-out-of-greenland-say-scientists/>

While we are dealing with the Vikings, may be either Daniel Bailey & doug_bostrom can inform me of how this information is off topic.
The farm under the sand
Researcher challenges conventional thinking on disappearance of Viking community
"The Norse arrived in Greenland 1,000 years ago and became very well established," says Schweger, describing the Viking farms and settlements that crowded the southeast and southwest coasts of Greenland for almost 400 years.
"The Greenland settlements were the most distant of all European medieval sites in the world," said Schweger. "Then the Norse disappear, and the question has always been: what happened?"

Cross-sections of the GUS soil show the Vikings began their settlement by burning off Birch brush to form a meadow. Over the next 300 to 400 years, the meadow soil steadily improved its nutritional qualities, showing that the Greenland Vikings weren't poor farmers, as McGovern and others have suggested. "At GUS, the amount of organic matter and the quality of soil increased and sustained farming for 400 years," says Schweger. "If they were poor farmers, then virtually all the farming in North America is poor farming."
<https://sites.ualberta.ca/~publicas/folio/38/16/03.html>

''We find that major temperature changes in the past 4,500 y occurred abruptly (within decades), and were coeval in timing with the archaeological records of settlement and abandonment of the Saqqaq, Dorset, and Norse cultures, which suggests that abrupt temperature changes profoundly impacted human civilization in the region. Temperature variations in West Greenland display an antiphased relationship to temperature changes in Ireland over centennial to millennial timescales, resembling the interannual to multidecadal temperature seesaw associated with the North Atlantic Oscillation. ''
<http://www.pnas.org/content/early/2011/05/23/1101708108.abstract>

Medieval Warm Period was warmer

J Doug Swallow at 01:48 AM on 10 August, 2017

"[DB] One would think that in the 5 years since your last participation here that you'd have learned to comport your comments better with this venue's Comments Policy. Simply copy/pasting up a paper from years ago selected at seeming random with no cogent context of your own added is just sloganeering (snipped)."
I became aware 5 years ago that unless a comment comported without a doubt with the message that you were trying to push, it would end up like this one that I sent your way.

This is what I have found and if it doesn't meet your standards that is because you have no interest in discovering what the truth is if it contradicts your forgone, unsubstituted conclusions. It appears from your uninformative reason why my comment didn't "comport" to your very dodgy Comments Policy, that in your mind, when you say; "a paper from years ago", that you are now saying that valid scientific evidence backed up by the Earth Sciences department at Syracuse University, Syracuse, NY, The American Geophysical Union & Harvard University has a shelf life and if it exceeds a certain time frame it is deemed invalid.

After going over more of the comments I now see what type of comment "comports" to your rigorous standards.
MrN9 at 00:23 AM on 26 April, 2015 "Glenn Tamblyn and DSL. What my point is that what is being discussed here is the wrong "myth". It's not about people thinking: "The Medieval Warm Period was warmer than current conditions. This means recent warming is not unusual and hence must be natural, not man-made." ... People think something more like... "Oh look, people who talk about global warming pick and choose the data which they tell us about, and omit that which does not support their view so as to make their own view sound more convincing". Exactly how warm or not the MWP may or may not have been is irrelevant. Most will never understand the complexities of the issues, this is about trust…"
The wealth of information to be derived from the above comment is truly astounding, wouldn't you say, [DB]?
Now for one of my comments that did not comport.
SAO/NASA ADS Physics Abstract Service
An ikaite record of late Holocene climate at the Antarctic Peninsula
Lu, Z.; Rickaby, R. E.; Kennedy, H.; Pancost, R. D.; Shaw, S.; Lennie, A. R.; Wellner, J. S.; Anderson, J. B.
That this report has Affiliation with (I will not show the long list of scientific organizations affiliated with this study, Skeptical Science, for obvious reasons, is not mentioned)
Publication Date: 12/2011
"Our interpretation, based on ikaite isotopes, provides additional qualitative evidence that both the Medieval Warm Period and Little Ice Age were extended to the Southern Ocean and the Antarctic Peninsula."
http://adsabs.harvard.edu/abs/2011AGUFMPP51A1819L
This ikaite record qualitatively supports that both the Medieval Warm Period and Little Ice Age extended to the Antarctic Peninsula.
<http://adsabs.harvard.edu/abs/2012E%26PSL.325..108L>

I'm not sure if in this case who [DB] is. I am guessing that it is doug_bostrom. I like it in these kinds of discussions when people have enough confidence in their believes to use their real names.

Medieval Warm Period was warmer

J Doug Swallow at 01:34 AM on 9 August, 2017

This report below is certainly more believable than what Skeptical Science puts forth when they claim that: "The Medieval Warm Period was not a global phenomenon. Warmer conditions were concentrated in certain regions."
Earth and Planetary Science Letters
Volumes 325–326, 1 April 2012, Pages 108–115
An ikaite record of late Holocene climate at the Antarctic Peninsula
This ikaite record qualitatively supports that both the Medieval Warm Period and Little Ice Age extended to the Antarctic Peninsula.
Highlights
► Ikaite forms in a narrow and shallow zone. ► Natural crystal (in modern porewater) validates the fractionation factor from lab. ► Trends in ikaite δ18Ohydra and δ18OCaCO3 are comparable with other records. ► Ikaite record indicates that the influence of LIA and MWP reached the AP.
<http://www.sciencedirect.com/science/article/pii/S0012821X12000659>

Medieval Warm Period was warmer

J Doug Swallow at 01:31 AM on 9 August, 2017

"The 2485-year temperature data used in this study are taken from reference [13]. This temperature series is not only representative of the central-eastern Tibetan Plateau, but also the vast area of central-northern China. It is also significantly correlated with seven other temperature series of the Northern Hemisphere [13]. It even has a teleconnection with series for middle-low latitudes in the Southern Hemisphere [15]. Therefore, the spatial representative of this temperature series is quite clear. Since a conservative negative exponential or linear regression is employed in the detrending process, most low-frequency signals are preserved in the chronology and can be used to detect the low-frequency components of climate change."
http://www.agbjarn.blog.is/users/fa/agbjarn/files/tibet-2485_years.pdf

Those 80 graphs that got used for climate myths

ubrew12 at 06:03 AM on 13 July, 2017

I remember being directed to a website purporting to show all the different studies, around the World, that supported the 'Medieval Warm Period' (WMP) as a global phenomenon. It was certainly impressive: a large compendium of studies (most of them anecdotal). First thing I thought was: who has the time to compile such an impressive array of studies and yet doesn't have the time to properly integrate those studies for year and location? My answer is someone whose purpose is to cast shadow and not light. They're betting that most people will be blinded by the sheer number and give up and just accept the conclusion of the web-site.

Models are unreliable

Tom Dayton at 11:40 AM on 27 June, 2017

NorrisM, initially I'm going to assume you are who you claim to be, though the content of your post makes me suspicious--very suspicious--that you are one of SkepticalScience's fake-skeptic, trolling, chronic sock-puppeteers, and one in particular.

Your statement

The APS panel consisted of six (6) arm’s length physicists (with no axe to grind) chaired by Steve Koonin who were asking hard questions of both sides. What actually struck me as very astounding was how honest Koonin was about his previous lack of understanding as to how uncertain climate science is owing to the uncertainties underlying the climate models.

is incorrect. Steve Koonin is a notorious fake skeptic, who has both the background and the subsequent, repeatedly delivered, information to know that most of what he says and writes is factually and drastically incorrect. Christy has and continues to make claims that are factually incorrect, and is motivated primarily by political and religious beliefs. Christy's partner in crime is Roy Spencer, who is a member of the Cornwall Alliance that claims human-caused global warming is impossible because God promised Noah there would not be any more floods. Really. LIndzen's pet theory about the "iris" mechanism that self-regulates the Earth's temperature conclusively and repeatedly has been proven wrong (obviously, since Earth's temperature has varied drastically--Snowball Earth, ice ages,...) but that has had no effect on his opinion, and he very much resents and takes personally the criticisms. Curry once was an adequately productive climate scientist, but for reasons I won't speculate on here, has become quite the opposite.

To lead on climate, leave the ivy tower

nigelj at 08:21 AM on 22 June, 2017

Agreed, universities should join this coalition and show leadership. But perhaps these universities are worried about a backlash if they openly join this coaltion? Backlash could come from a variety of parties sceptical of climate science, and influential in education.

Some people probably think the laws of science can be "negotiated". There is a powerful, toxic, anti science, anti intellectual bullying movement in America, and it want's to control what universities do. It is utterly delusional, and will lead to ignorance, and your economic and social destruction. It's a return to the stagnation and values of the fuedal middle ages period. (the so called medieval "warm" period)

2017 SkS Weekly Climate Change & Global Warming News Roundup #16

nigelj at 12:08 PM on 26 April, 2017

Joe @1, I don't see how you can say that this rivers natural drainage basin existed back in the mwp, because this is arbitrary. I could equally say it's natural drainage basin was back before the mwp where things were probably different yet again, but this is just as arbitrary. Rivers change their courses long term.

I think the only meaningful definition of natural drainage basin would be "before humans substantially changed things" for example by agriculture and hydro power etc, or by agw global warming, depending on specific rivers. This would mean natural drainage basins are far more recent than the mwp.

The real point is we are causing the glacier to melt through burning fossil fuels, or are at least this is a dominant cause. And its happening at a fast rate compared to previous warming periods like the mwp. And its altered river flows.

The glacier has indeed revealed some tree stumps from very roughly around the mwp. However studies of the mwp find that for Europe as a whole, it was rather weak with about half a degree of warming, in the northern hemisphere only, as below

(LINK)

The mwp was also rather short, and was clearly not enough to seriously raise sea levels long term. The recent agw warming is driven more by greenhouse gases, and is at a much higher rate, and likely to lead to long term sea level rise.

We're heading into an ice age

scaddenp at 12:36 PM on 8 April, 2017

"should be a caveat that those Pliocene-Pleistocene Series precursors to our current situation had to have had both non-anthropormorphic entrances to and exits from their warm periods."

I am not quite sure I follow you, especially with regard to entrance/exit of warm periods. In very broad terms, CO2 has been falling right through the Cenozoic, with exception of PETM. In transition from Pliocene to Pleistocene, CO2 (and surface irradiation) had fallen to level where Milankovich cycles could drive an ice-age cycle. Prior to then, climate was too warm (and CO2 too high). Noone is disputing that orbital forcings drive the Pleistocene ice ages, though turning variations in albedo at 65N into a global event involves several feedbacks of which CO2/CH4 feedbacks are very important. These are hardly analogues of current situation. The pace of change for a start is orders of magnitude faster. If we keep warming, we will also get carbon cycle feedback enhancing the warming but not for 100s of years.

Perhaps time to look at "Climate has changed before" article as well? Or have I completely misunderstood you?

CO2 lags temperature

MA Rodger at 01:06 AM on 24 February, 2017

Adri Norse Fire @558.

You will appreciate that I am only able to interpret your written words. @532 you appear quite definite saying “The question is whether we have the highest concentration of atmospheric CO2 in 800,000 years, without going further, why the current temperature is 1.5 ° lower than the medieval warm period?“ I did point out that the value “1.5 ° lower” was not properly defined as the units of degree were absent. But if you have modified your position to be now arguing that “500 to 1000 years ago, temperatures were warmer than today,” that is fine. However do note you are wrong to say that such a statement is “valid for (your) initial question.” It is not.

Also it is wrong to cite Broecker (2001) in the manner that you do. Broecker do reference Huang et al (1997) in the manner you quote and Huang et al do set out that data supporting their findings. Indeed, Huang et al do provide a significant portion of the evidence for a global MWP presented by Broecker. However Broecker (2001) concludes “The case for a global Medieval Warm Period admittedly remains inconclusive.” And the graphic you provided @532 which attempts to use Broecker (2001) to support itself is, as explained @543, utter garbage.

Your defence of the second graphic you presented @532 doesn't explain why the Dye 3 temperature profile developed by Dahl-Jensen et al (2009) is omitted. Nor does it explain the second trace on the graphic you presented. Nor does it provide any resolution to the case for a global MWP. As set out @543, that graphic is also utter garbage.

The data presented in the third graphic @532 ends at 1935. I thought mention of the global warming 1935-to-date establshed by the global thermometer record would prevent your use of the 1935 end-point of that graphic to support your unsupported assertions. I can but repeat that you are wrong to do so.

And the fourth you now agree is garbage.

Your final point in this particular list @558 seems to be saying that someone can misuse data if it comes from a legitimate source. That is very wrong. You do require to show use of legitimate data by “those who did it,” with “it” being the proper use of NASA data to predict "a new short cold period ... between 2030 and 2050." The best of luck with that fool's errand!!

But I should make plain that this discussion of individual data sets (and the garbage) is not the proper way to develop a case for asserting that “500 to 1000 years ago, temperatures were warmer than today.” Always the first step should be to assess the present state of the science on the subject. Although it is a few years old now IPCC AR5 is surely the place to start, particularly Chapter 5 - Section 5.3.5 or perhaps more helpfully the Technical Summary Section TS.2.2.1. You will quickly see that you will have quite a job on your hands asserting that “500 to 1000 years ago, temperatures were warmer than today.”

Your additional web-links @558 add nothing to this situation. They concern the future, not the past. And in this, Zharkova et al (2015) is solely talking about the sun not our climate. The garbage you link to in the English-speaking press is entirely wrong in suggesting there is a prediction of climate within this work. Indeed, does not your German link say “Kein Effekt auf globale Erwärmung “?
And if you think Abdussamatov (2013) is worth quoting (as your Forbes link does), do note the scientific response since publication – he has gained the attentions of nothing but a tiny pile of denialists. And that is because Abdussamatov (2013) spouts garbage.

CO2 lags temperature

Adri Norse Fire at 04:20 AM on 23 February, 2017

Why do we have to converse in English? I'm tired of cutting and pasting into the google translator and then I have to interpret what you mean. I guess it's my fault because this is a web in English.

Tom Curtis

You have described very well the improved method that used PAGES 2000, but that does not imply that it is a truly impartial reconstruction because as I said to have more markers in some continents than in others, in doing the average the global reconstruction has a better representation of certain parts of the world than others and the final reconstruction is biased. When you have many more proxies in some areas than in others, the average of the continents is partial in not having a similar number of proxies in the different areas. In other words the final result will approximate more faithfully to some means than others and therefore will condition the global average. To have a really faithful chart, they should have many more proxies in Africa, for example. But as you say, the PAGES 2000 chart is more reliable than that of Loehle and McCulloch. But back to the beginning, what about my appreciation on the PAGES 2000 chart?

MA Rodger

It is true what you say about the first chart, but the paper it refers to also says: ''From an analysis of 6000 continental borehole thermal records to ammonia the world (14), Huang et al. Conclude that 500 to 1000 years ago, temperatures were warmer than today, '' Which is valid for my initial question.

The second chart has probably been made by the man shown below, '' Nasif Nahle '' from the three sources he quotes. But the temperature of the chart is at least exactly the same as that of Dahl-Jensen's study and in that study it also says: '' The last 10 ky BP. The CO is 2.5 K warmer than the present temperature, and at 5 ka the temperature slowly cools toward the cold temperatures found around 2 ka. (C) The last 2000 years. The medieval warming (1000 A.D.) is 1 K warmer than the present temperature, and the LIA is seen to have two minimums at 1500 and 1850 A.D. The LIA is followed by a temperature rise culminating around 1930 A.D. Temperature cools between 1940 and 1995. ''

If you have a good eye you will see that the third graph shows that the peak temperature is 0.7 no to 0.5 therefore there does not seem to be much difference between today and the Medieval Warm Period according to that chart.

And as for the last chart, I agree with you that it is a slop. But it seems that you have missed one of the first graphics I put. The CO2 graph for 800,000 years. Maybe you should dissect it too, do not misunderstand me, I still like the dissections you do.

It is true as you say that NASA has not made these findings public, but those who did it, have been using the data provided by NASA, as you can see here: https://solarscience.msfc.nasa.gov/SunspotCycle.shtml

Rob Honeycutt

Very good. You really are right, but I'm not starting from scratch. Obviously I am not an expert and I recognize that I do not defend very well in the details, but I think I know something more than the average about science.

You already have your answer, but you must admit that it is good for you as a scientist (if you are) to have someone come forward to rebut your arguments. If something is really scientific it must be susceptible of being falsified or refuted, right? Science advances through essay and error. I'm doing you a favor, then.

scaddenp

So no statement of any documentary on science is true? First of all, I did not say that this is how "science works", of course not, I mean that is how science is taught to the public. And Jane Goddall teaches science through the media, as much as David Attenborough. I have no reason to distrust more of one man whose base is in Antarctica, than what you tell me.

<Hmm, so it would appear you have again unskeptically accepted a comment from what source ??> You can see that Tom Curtis himself confirms it (That there are a lot of non-scientific staff).

You build on this subject in a supposed consensus that does not exist, perhaps in public and political opinion itself. But I have seen that in the scientific community the subject is far from being consensual, although the majority supports the anthropogenic global warming. It's not like I said before, like the law of gravity.

<You claim climate science is based on untested assumptions. Which would these be?> That the share of CO2 produced by human emissions causes current global warming, for example.

<You? Or are your biases too powerful?> Haha, well I am not angry and as you have been able to check now, the graphics I put are not very good, but neither are the rubbish to which Mr. MA Rodgers alluded.

Tom Curtis

Again, thank you for the information. And yes, I immediately noticed that appreciation.

-------------------------------------------

And I want to add something, you do not seem very convinced about the solar theory to which I alluded and is normal if you are not familiar with it. I just want to say that I do not know your age, I will be alive between 2030 and 2050 but I guess those who live with me will be able to see it firsthand.

And for MA Rodgers, I have just remembered the names of leading Russian scientists who have come to similar conclusions on this subject, Mr. Abdusamatov and Mrs. Zharkova.

http://www.wetter.at/wetter/welt-wetter/Sonne-extrem-ruhig-Kommt-Mini-Eiszeit/241375001

http://www.express.co.uk/news/science/723481/Earth-ICE-AGE-big-freeze-solar-activity

http://www.dailymail.co.uk/sciencetech/article-3156594/Is-mini-ICE-AGE-way-Scientists-warn-sun-sleep-2020-cause-temperatures-plummet.html

http://www.forbes.com/sites/larrybell/2014/01/21/miss-global-warming-yet-if-not-just-wait-and-you-might/#c2e266161996

https://www.omicsgroup.org/journals/grand-minimum-of-the-total-solar-irradiance-leads-to-the-little-ice-age-2329-6755.1000113.pdf

https://www.youtube.com/watch?v=7sh_nlz43Pc

I do not know why but it seems that there is an error in the server of Nature about the article of the Mrs. Zharkova, perhaps a ray? Just write it on google and try to have it if you can. Best regards.

CO2 lags temperature

MA Rodger at 07:03 AM on 18 February, 2017

Adri Norse Fire @541,

The graphics you present do not support your assertions of a toastie warm MWP. In truth, they are a bit of a joke.

The first graphic Change of T & Change of CO2 Holocene Epoch is not supported by the document it says it sources for temperature data - Broecker (2001). While this paper itself is old and in many respects speculative, it does set its position out that "Holocene temperature fluctuations ... were probably less than 1°C." So for this graphic you present to show fluctuations of 8°C puts it quickly in the bin.

The second graphic plots a tiny part of one of two a Greenland borehole temperature reconstruction from Dahl-Jensen (1998) but the graphic for some reason cites a secondary source (Bond et al 2001). The other trace on this graphic is called Yang-Delta T but what this is plotting is not entirely clear. I would assume it is the 'weighted' China trace from figure 3 in Yang et al (2002) but there appears to have been some fiddling with this data in the most recent period plotted.

The third graphic is simply figure 2 from Loehle & McCulloch (2008) which presents a global temperature reconstruction to 1935. Note the peak of the MWP sits just 0.5°C above the 1935 level. Thinks - I wonder what has happened to global temperatures since 1935?

The final graphic is another stab at Holocene temperature & CO2 levels with various temperature reconstructions presented (including the borehole data used in the first graphic above) citing Bond et al (2001) again. It certainly is plotting out the bottom two traces from fig 5A in the paper but using the wrong x-axis. Of the other two traces presented, one does seem to be using the x-axis properly but where it is sourced is not at all evident. And as a parting shot at this rubbish, note that the CO2 trace in this graphic is saying CO2 topped 300ppm in about 1780AD, assuming the grapher managed to plot it against the x-axis correctly. If the x-axis is wrong, the y-axis is also up the spout as well.

CO2 lags temperature

Adri Norse Fire at 23:41 PM on 17 February, 2017

MA Rodger
What I meant was that I am using scientific data in the sense that my arguments are exclusively in scientific terms, regardless of whether my claims are true or not.

Rob Honeycutt/scaddenp

Why do you say that I am not using scientific data? Do not scientific documentaries and scientific journals make scientific knowledge public? Is that knowledge invalid? So everything the public knows is a lie ... including global warming, right?

When I said that the current temperature was below about 1.5 ° I relied on a documentary where a gentleman, I think he was Norwegian who was in the Antarctic and claimed that the ice cores of his own research proved that the temperature was 1.5 ° higher to the present during the Medieval Warm Period. But also, it is known that historically the peoples of contemporaries of that time recorded that in Greenland agriculture was possible, among other things, etc. I think it is out of place to think that everything is part of a subtle conspiracy, of wich I am part, of course.

Tom Curtis

Thank you.

Okay, this is the kind of thing I said that misinterpretations were likely to occur. I have not said that the current increase in CO2 comes from volcanoes. And you're right, I thought it was a question I asked John Hartz, it's my fault. Sorry. Again you are right, I have no problem accepting that the recent increase in CO2 is due to human industrial activity, although there are other scientists who deny that conclusion with their own data, since from the beginning I said CO2 does not cause the current global warming by greenhouse effect or by feedback. I just do not see it likely. Sources I read some time ago claimed that water vapor is the main greenhouse gas and that it is responsible for two-thirds of the natural greenhouse effect. As you say very well it is a stable process, but the Earth makes all kinds of movements and we do not really know how much impact the orbital changes have on the greenhouse effect and Milankovich attributed the intervals of glacial periods and warm periods to the orbital changes. Which is no small thing in terms of climate.

Sorry for putting that graphic, I knew it was just a very nice graphic. I have taken note.

Well, as I said above the Antarctic data show also, that the temperature was higher than the current approximately 1.5 degrees during the Medieval Warm Period.

"All of this may be a side issue, but I am unsure as to what point you are trying to make with two charts of CO2 concentration over the last 800,000 years, or the chart of CO2 concentration over the Holocene." Why the current Temperature is 1.5 ° lower than the medieval warm period? " It is not. See chart above.'' Yes it was, why do you think it was called the Medieval Warm Period? Let's look at some recent research:

Working with a 2.5-foot-long core of peat in Penido Vello (Galicia, Spain) Martinez-Cortizas et al. (1999), a Mercury deposit record was extracted that extended until 4000 years ago. The work revealed that warm periods were characterized by a low accumulation of mercury. They also standardized the variables extracted and related them to the temperatures of the last 30 years. The work revealed that the medieval warm period in the northwest of Spain was 1.5 ° C warmer than the current one and that the average temperature of the warm Roman period was in no less than 2 ° C. Even a period of 80 years in the Middle Ages with average temperatures 3 ° higher than the current ones.

Desprat et al. (2003) studied the climatic variability of the last three millennia through the sediments of the Vigo estuary, clearly recognizing three warm periods and three cold periods, without seeming to be a relation between the variability and the increase of carbon dioxide. The authors concluded that the solar radiative balance and the ocean circulation seem to be the main mechanisms that force these cyclical variations in the Peninsula.

Pla and Catalan (2005) analyzing sediments of chrysophytes in more than 100 lakes of the Pyrenees reproduced a record of winter and spring temperatures during the Holocene. Warm and cold oscillations were recognized for these oscillations over the past few millennia. From the Medieval period it is deduced that the temperatures were then 0.25 ° higher than the current ones.

Here a chart: http://www.biocab.org/Holocene-Delta_T_and_Delta_CO2.jpg And as I liked the dissection you did to the other here is more: http://www.biocab.org/Boreholes_Reconstruction.jpg http://3.bp.blogspot.com/_H07QGNhZQzA/S_gGpyDlDQI/AAAAAAAAAHw/ADQvLwN-9U0/s1600/temperaturas+%C3%BAltimos+2000+a%C3%B1os.jpg http://www.biocab.org/Holocene_Delta_T_and_Delta_CO2_Full.jpg

''Of course, in your version it is labelled Northern Hemisphere temperatures, not global temperatures. The point still stands, however. A Greenland ice core no more shows Northern Hemisphere temperatures by itself than does a thermometer in Moscow show temperatures in Tucson, Arizona.'' The question then remains valid, but to avoid falling into the little trick of geography I will rephrase: Why the current temperature of Spain is lower (0,25º - 1,5º) than the Spain's Medieval Warm Period, if the current concentrations of atmospheric CO2 in Spain is higher without any doubt?

(Can we extend the geographical scope to the Mediterranean and even Europe? I do not know; http://science.sciencemag.org/content/291/5508/1497 , http://science.sciencemag.org/content/342/6158/617)

--And someone asked me why I'm so skeptical or something--

Well, it is not very difficult to be a skeptic of anything since we have been able to see everything from the millionaire Red Cross scam in Haiti after the earthquake to hear the Greenpeace co-founder say that this organization has become a corrupt gang and then you see scandals with emails and what some IPCC scientists say, and so on. When I saw the Al Gore's documentary I believed it and when I saw the documentary of The Great Scam of Climate Change, I also believed it. So we must be very careful not to be deceived by the official tone, as some have pointed out: http://joannenova.com.au/2010/10/is-the-western-climate-establishment-corrupt-part-4-past-temperatures/

MA Rodger

It's funny that you mention sidelong to the ''Little Ice Age revivalists'' because according to NASA members, this very century we can face a solar minimum such as the Maunder Minimum or the Dalton Minimum and presumably a new Little Ice Age. Here's a link: http://www.forbes.com/sites/peterferrara/2013/05/26/to-the-horror-of-global-warming-alarmists-global-cooling-is-here/#5c8c582669bb

CO2 lags temperature

Tom Curtis at 08:21 AM on 16 February, 2017

Adri Norse Fire @532, first, let me say you are coping quite well with the language difference given that you are using a machine translator.

"''What is worse, you ask, "How do they know that CO2 does not come from other sources that also have low levels of radicarbon But or course, Daniel Bailey has already answered that question with 10 lines of evidence.'' He didn't and this answer was not addressed to him"

On the contrary, five of the ten lines of evidence falsify the theory that the increase in CO2 in modern times is a consequence of increased vulcansim; and a sixth renders it unlikely:

As fossil fuel and volcanic CO2 are the only C14 - free sources of carbon on the Earth, that precludes the origin being a C14 free source other than fossil fuels.

I am not sure what you meant by "this answer was not addressed to him" given that the sentence I quoted clearly came from the section of your comment headed "Daniel Bailey". I assume it is an inaccurate translation.

"I did not say that CO2 or CH3 does not produce a greenhouse effect, but the feedback effect of CO2 and other minor gases is irrelevant to climate compared to other greenhouse gases."

It is true that water vapour is a significant feedback on any warming. However, it contributes approximately 1C of warming for each 1 C contributed from another source. That means that for the glacial/interglacial cycle, including water vapour, albedo effects will have most likely contributed <30% directly, CO2 and CH4 <25%, with H2O most likely contributing <45%. Less than, because there are other short term feedbacks that are most likely to contribute about 0.5 C for each 1 C of direct warming, but may contribute 4 times that amount, but may have been a negative feedback.

Firstly, I will note that 6 - 25% contribution from CO2 and CH4 (once we account for the effect of water vapour) is not a negligible contribution.

Secondly, I will further note that H2O has a very short time to return to equilibrium in the atmosphere (weeks), so that its total atmospheric contribution is almost entirely governed by temperature. That means when we wish to determine the effect of an increase in CO2 concentration on the Earth's temperature, we can treat H2O as a feedback - and need not track it independently. That is particularly important for graphs such as this one:

It is well known that the direct temperature effect of a change in forcing is about 1 C to 1.2 C per 3.7 W/m^2 change, and hence about 0.8 to 0.9 C for the change in forcing from last glacial maximum to the holocene. The calculation of the implied sensitivity, therefore, is not an attempt to determine that direct effect, but to determine the result of the direct temperature effect plus all short term feedbacks, including H2O. That turns out to be about 2.8 C per 3.7 W/m^2.

Because I (and others) understand the purpose examining the causes of the difference in temperature between the last glacial maximum and the holocene, we do not bother mentioning the details about components of the short term feedbacks. I will grant that when talking with a popular audience, who are not aware of the reasons for focussing on CO2 and change in glacial ice extent, that is a mistake. We should clarrify the role of short term feedbacks, and why we are focussing on CO2 (as I have now done).

"If you like correlations so much why do not you look for some of the temperature and CO2 for the last 10,000 years? Does this correlation count as evidence?"

First, if you want to be taken seriously in a scientific discussion, don't source evidence from astrology sites, as you have done with that first chart. Granted the author of that site attributes the chart to a climate scientist (Schoenwiese) without specification as to year, or publication. Fortunately the chart has been examined as an example of the misuse of scientific charts by climate "skeptics" (Schneider et al 2014). The chart is from Schoenwiese 1995, and based on Daansgard (1984) (published online in 2013). Schneider et al (2014) comment:

"many authors of skeptical media (for example Avery, 2009, and Vahrenholt und Lüning, 2012) fail to mention that this temperature estimate is based on an ice-core record from Greenland and may thus not be representative of global temperatures."

Of course, in your version it is labelled Northern Hemisphere temperatures, not global temperatures. The point still stands, however. A Greenland ice core no more shows Northern Hemisphere temperatures by itself than does a thermometer in Moscow show temperatures in Tucson, Arizona. It can be used (as Daansgard used it) as an indication of North Atlantic temperatures, but beyond the North Atlantic, its accuracy as a temperature index will rapidly fall.

Schneider et al go on:

"Most importantly, in Schönwiese's 1995 version the current and near future temperature changes are included. The recent warming goes far beyond the historic warm periods of the last 12000 years and should therefore have been included in the graph."
(My emphasis)

You should recognize that yourself. Taken at face value, the chart indicates that the Little Ice Age terminated 400 years ago. If we allow a more recent (circa 1850) termination then we must, according to that chart, acknowledge that for most of the LIA it was as warm as the peak of the Medieval Warm Period; and of course, that temperatures have since risen significantly above that peak.

Finally, here is a chart which has a fair claim to represent global holocene temperatures (but note caveats):

Note that 2004 is significantly warmer than any period prior to 1900, and that it has warmed appreciably since then.

All of this may be a side issue, but I am unsure as to what point you are trying to make with two charts of CO2 concentration over the last 800,000 years, or the chart of CO2 concentration over the Holocene.

"why the current temperature is 1.5 ° lower than the medieval warm period?"

It isn't. See chart above.

CO2 lags temperature

MA Rodger at 02:07 AM on 16 February, 2017

Adri Norse Fire @532.

You say you use "scientific data." The four graphs you present do not provide scientific data of temperature. Instead the one temperature graph you do present is schematic, and also flat wrong. It says it plots Northern Hemisphere temperatures yet shows less than 0.1ºC increase in NH temperature since 1850. HadCRUT4 (which is known to underestimate the warming due to poor Arctic coverage) puts the NH temperature increase since 1850 at 1.05ºC while GISTEMP (which provides a more realistic assessment of Arctic temperatures) puts the rise since 1880 as 1.25ºC. Note also that this graph you present does not support your assertion that "the current temperature is 1.5 ° lower than the medieval warm period."(And that stands whatever the º you intend.)

CO2 lags temperature

Adri Norse Fire at 00:17 AM on 16 February, 2017

Well, I did not mean to sound pedantic. First of all I want to say that I am not a native speaker of English, I am using the translator to talk to you ... and that may cause some misunderstanding. Anyway, I apologize.

Rob Honeycutt

I am not working hard to deny anyone, what I say is what I have seen in documentaries and in magazines, that's all. I'm not an old scientist. But unlike you, Rob, I do not see that the establishment in which you believe has an indestructible foundation, this is not like the theory of gravity, there is a plenty of people who are also scientists who disagree with you In this subject or with the supposed orthodoxy to which you refer.

'' Why do you think you're dismissive of the science? ''

I do not despise science, I think that until now my arguments have not been ideological but scientific data that obviously are within the reach of all.

Tom Curtis

I want to remember that my first comment was a few months ago, having that in perspective; You're right when you say that my last answer does not exactly respond to his response, but I was thinking in the background of the whole conversation that was whether CO2 and therefore human industrial activity are causing the global rise in temperature.

''What is worse, you ask, "How do they know that CO2 does not come from other sources that also have low levels of radicarbon But or course, Daniel Bailey has already answered that question with 10 lines of evidence.'' He didn't and this answer was not addressed to him; That's why I said "sorry for my ignorance," because if you can not know how much low-radiocarbon CO2 comes from other natural sources due to lack of studies on the subject or for any reason, how can you faithfully calculate the amount Of CO2 emitted by human industrial activity? I mean, we can distinguish that something has different properties, but we do not seem to know how these properties work or whether they hold them through their natural cycles which is an imperative for the final calculation.

I did not say that CO2 or CH3 does not produce a greenhouse effect, but the feedback effect of CO2 and other minor gases is irrelevant to climate compared to other greenhouse gases.

If you like correlations so much why do not you look for some of the temperature and CO2 for the last 10,000 years? Does this correlation count as evidence?

http://www.lunarplanner.com/SolarCycles-images/Climate-Timeline-10000yrs.png

http://www.ferdinand-engelbeen.be/klimaat/klim_img/antarctic_cores_800kyr.jpg

And what about this chart?

http://kabarkampus.com/wp-content/uploads/2014/04/Dede-Prabowo-Wiguna_ilustrasi-1.jpg

http://s3.amazonaws.com/wboc-digital/production/sites/wboc-weather/wp-content/uploads/2016/04/28214154/Capture21.png

The question is whether we have the highest concentration of atmospheric CO2 in 800,000 years, without going further, why the current temperature is 1.5 ° lower than the medieval warm period?

''Finally, I will note that "recovery from the Little Ice Age" is a description of what the temperature does over a period ending about 1850. It is not an explanation of that warming.'' Indeed it is an assumption that the rise in temperature was related to the Little Ice Age. This also explains the warming of the 20th century. Someday I'll explain my crazy theory, but not right now. I apologize again.

John Hartz

Only me?

NOAA was right: we have been underestimating warming

nigelj at 06:05 AM on 7 January, 2017

Echo Alpha Zulu @7 says:

"According to borehole samples collected from Greenland only temperature anomolies still have not increased to what they were 2000 years ago. I am not invalidating your data as it is correct, it is just misleading."

Echo, Greenland is just one place, and could be an anomaly as different places change at different rates. You have to look at a wide selection of countries, and reach an average. Many studies of the medieval warm period do this, and find it was a weak event, eg Briffa, Esper, Jones. Unfortunately it is your post that is misleading.

NOAA was right: we have been underestimating warming

Tom Dayton at 04:56 AM on 7 January, 2017

Echo, you wrote "I will ask you to provide us with a chart of temperature records over the past 2000 years." Okay--see the post on the Medieval Warm Period. After you read the Basic tabbed pane, read the Intermediate one. For more information about the PAGES 2K study that is cited and graphed there, see a post on that. If you want to discuss those topics, do so in the comments on those or similar posts, where your comments will be on topic.

Tracking the 2°C Limit - November 2015

KR at 03:07 AM on 14 January, 2016

angusmac - While that map (generated by Dr.s Lüning and Vahrenholt, fossil fuel people who appear to have issues understanding fairly basic climate science) an interesting look at the spatial distribution of selected proxies, there is no time-line involved in that map, no indication of what period was used in the selection. No demonstration of synchronicity whatsoever. Unsurprising, because (as in the very recent PAGES 2k reconstruction of global temperature):

There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age...

As to IPCC AR5 Chapter 5:

Continental-scale surface temperature reconstructions show, with high confidence, multi-decadal periods during the Medieval Climate Anomaly (950 to 1250) that were in some regions as warm as in the mid-20th century and in others as warm as in the late 20th century. With high confidence, these regional warm periods were not as synchronous across regions as the warming since the mid-20th century. (Emphasis added)

You are again presenting evidence out of context, and your arguments are unsupported.

---

But this entire discussion is nothing but a red herring - again, from IPCC AR5 Ch. 5, we have a fair bit of knowledge regarding the MCA and LIA:

Based on the comparison between reconstructions and simulations, there is high confidence that not only external orbital, solar and volcanic forcing, but also internal variability, contributed substantially to the spatial pattern and timing of surface temperature changes between the Medieval Climate Anomaly and the Little Ice Age (1450 to 1850).

Whereas now we have both external forcings (generally cooling) and anthropogenic forcings, with the latter driving current temperature rise. In the context of the present, a globally very warm MCA and cold LIA would be bad news, as it would indicate quite high climate sensitivity to the forcings of the time, and hence worse news for the ongoing climate response to our emissions. I see no reason to celebrate that possibility, let alone to cherry-pick the evidence in that regard as you appear to have done.

Tracking the 2°C Limit - November 2015

KR at 14:32 PM on 12 January, 2016

angusmac - "I only stated (and cited references) that showed that temperatures in the MWP were similar to 1961-1990 mean tempratures."

During the Medieval Climate Anomaly, a period of several hundred years, various regions reached temperatures similar to the latter half of the 20th century. But very importantly, not simultaneously - as per the recent PAGES 2k reconstruction:

There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age...
[...] Our regional temperature reconstructions (Fig. 3) also show little evidence for globally synchronized multi-decadal shifts that would mark well-defined worldwide MWP and LIA intervals. Instead, the specific timing of peak warm and cold intervals varies regionally, with multi-decadal variability resulting in regionally specific temperature departures from an underlying global cooling trend".

There was no MCA shift in global temperature anomaly comparable to recent changes. This has been pointed out to you repeatedly, with copious documentation by Tom Curtis in particular - your continued insistence on a MCA similar to recent temperatures seems to indicate that you aren't listening to the evidence presented.

Tracking the 2°C Limit - November 2015

Tom Curtis at 19:54 PM on 11 January, 2016

angusmac @26, saying the MWP is global is ambiguous. Was the GMST durring the MWP warm relative to periods before and after? Yes, and in this sense it is a global event. Were there significant climate perturbances across the globe durring the MWP? Again, yes. And again, in this sense, the MWP was global. Were temperatures elevated in the MWP across most individual regions across the globe? No:

(Mann 2009; discussion)

There were areas on increased warmth, and areas of increased cold relative to the mid-twentieth century (1961-1990). So in this sense, the Medieval Warm Period was not global, although the Medieval Climate Anomally was.

In contrast, we truly are seeing global warming currently:

In any event, you would do well to not just assert that the MWP was global (or that it was not), but to clarrify just in which sense you mean that it was global. Failure to do so will only lead to confusion.

With regard to the figure, the source linked by the second link in my post @18.

Tracking the 2°C Limit - November 2015

Eclectic at 20:06 PM on 7 January, 2016

Unfortunately, Angusmac, the Huang paper is currently off-line at the link you gave.

My memory is sketchy, since it is some 2 years since I was reading on the NOAA website that the Medieval Warm Period . . . was more a North Atlantic phenomenon ~ during which, the Andean and West-Canadian glaciers were still advancing (plus some other Southern Hemispheric evidence). The gist of it was that the MWP was greatly overrated as an event of global importance.

Whether the (so-called) MWP should be discounted 50% or 75% (or not at all! ) in the discourse about "climate baseline" . . . there still remains the question of why you yourself should not equally favour the use of the Dark Ages Cold Period as the criterion baseline for AGW consequences. And like the MWP, the DACP is also susceptible to criticism !

In reality, neither Period is worthy of much consideration, because the vast amount of hard evidence we have about the Modern Period, is entirely superior as a basis for making important decisions (about climate).

Tracking the 2°C Limit - November 2015

Eclectic at 14:13 PM on 6 January, 2016

Why indeed not use for comparison the Medieval Warm Period ?

Or indeed, Angusmac, why not use the Dark Ages Cold Period, instead, as the baseline for comparison ?

Then also, for the MWP, we have the little problem ~ that the Southern Hemisphere did not have a comparable "MWP" . So, to avoid fruitless bickering . . . best if we stick with the much-better documented temperature information that we have for the latest couple of centuries. Clearly the best choice, by far.

Heat from the Earth’s interior does not control climate

michael sweet at 09:31 AM on 2 December, 2015

Maaark,

This web site has all the information that you ask about. It is not the responsibility of posters here to spoonfeed you the answer to your questions. It is your responsibility to look for it and inform yourself.

I typed "climate in the past has changed before" into the search box above and got this post which addresses your first question. Please read that post and then follow up with questions there where they will be on topic.

The OP here addresses your other question. It states:

"The net increase in the amount of planetary energy flow arising from human activities (mainly the greenhouse effects from emissions of carbon dioxide) since the industrial revolution is more than twenty times the steady-state heat flow from the Earth’s interior. Any small changes in the Earth’s heat flow over that time period—and there is no evidence for any change at all—would plainly be inconsequential."

If you have a question that is not addressed by this quote about mantle heat you need to be more specific about the changes you suggest which would increase heat flow by a factor of 20 without anyone noticing. The method of measuring the heat flow is described in the OP, it is not necessary for NOAA to install additional thermometers.

If heat from the mantle was warming the ocean, the ocean would warm from the bottom up. Extensive data shows clearly that the ocean is warming from the top down which contradicts your hypothesis.

Please make use of the search box, your questions will be better after you read more.

Climate's changed before

Tom Curtis at 01:47 AM on 18 November, 2015

MA Rodger @512, NN1953VAN-CA actually cites a 1.3 C temperature variation (from -0.8 to +0.5 C). Even that is incorrect, however. The actual temperature range for the mean value is -0.6 to 0.56 C, for a 1.16 C temperature range.

Even that is exagerated taken as a global value. That is because, of 18 proxies used, Loehle and McCulloch use 12 from the NH extratropics, 4 from the tropics, and 2 from the SH extratropics. As they take a simple mean of the proxies, they tacitly assume that 66.7% of the Earths Surface is in the NH extratropics, 22.2% in the tropics, and just 11.1% in the SH extratropics. The real values are 30.11% NH extratropics, 39.78% tropics, and 30.11% extratropics. Even within zones, the data is heavilly biased, with 8 of the 12 NH extratropical proxies coming from the North Atlantic Region (Europe and North America) and the rest from China, the tropical proxies coming from Indonesia and Africa, with South America excluded, and all SH proxies coming from Africa.

These biases matter. The NH varies more in temperature because of the greater percentage of land in the NH. The North Atlantic is known to be the region of greatest and most persistent temperature change due to the so called Medieval Warm Period. So not only are the proxies heavilly biased in coverage, the are biased in favour of areas known to have greater temperature variation before the proxies were chosen.

That bias extends to the fact that only 8 of 18 proxies (44.4%) are for SST, despite 70.8% of the surface being ocean. This strong terrestial bias again distorts the result given that temperature changes over land are greater than those at sea. (Odd how every bias in the data exagerates temperature variability.) Unfortunately, SST proxies are limited in number, and this particular bias is not atypical of paleo temperature reconstructions. That, however, means in turn that although error bars tend to be shown as symetrical for such reconstructions, in fact the reconstructions are more likely to exagerate variability than supress it.

Climate's changed before

A Real Sceptic Says at 05:05 AM on 31 October, 2015

Real sceptics ask the question, "Are the changes in climate that have occurred since significant human CO2 emission fundamentally different from those that occurred before?". If yes, that would support the CAGW view. If not, CAGW *could* still be true, but the recent climate changes could not be cited as support for it except in a weak, probabalistic way.

The problem is, for sceptics, that the support from the historical record has been repeatedly miserpresented and even falsified.

Firstly, the Michael Mann's "hockeystick graph", given prominence in Al Gore's propaganda work, is still cited from tie to time in spite of having been debunked. It shows climate as virtually constant for a millenium before human CO2 and in doing so ignores important changes such as the Medieval Warming Period, the Little Ice age, as well as a noticable warming trend in the hundred years or so before human CO2 emissions.

Other, more recent graphs are a good deal more honest about such things. However, the "trick" being used now is more subtle. These graphs are, without exception, smoothed to a far greater degree during pre-CO2 periods than the recent period. For example, you will see 100-year smoothing up to 1950, followed by 10-year or even unsmoothed data. It should not surprise that the less-smoothed period is less smooth - and the more bumpt section looks more alarming!

Graphs going back over many thousands of years are often even more heavily smoothed. I saw one recently that went back 400,000 years, meaning that it gave only 1 or 2 pixels to each 1000-year period, and yet the last 50-years was shown explicitly, with probably only 10-year smoothing. Now, if the underlying data has more resolution, then the correct way to show the data is with a shaded region between min and max values (so the fine variation may be seen), rather than a saeries of averages (which is just another way of hiding detail on shorter timescales).

To be fair, many studies will be intrinsically unable to uncover that fine detail. But when presenting that data, the fact that past rapid changes will not be present should be honestly pointed out. Not kept quiet.

Nearly every graph you now see of past trends is, whether by manipulation or limitations of the underlying study, not showing past rises of the kind seen in the last 50 years but only averages that would hide it. As a result, it would be incorrect to assume from them that such rises have not occurred.

Suppose for example we see a cold day followed by a hot day. Someone micht claim that is an unprecidented event. Suppose they show you a graph of the last year's temperature, and smooth that graph out by taking weekly averages. Of course you won't see any examples of the event having happened before - the smoothing process rubbed them out!

We're coming out of the Little Ice Age

Tom Curtis at 06:04 AM on 2 July, 2015

In an apparent flyby comment, arationofreason wrote here:

"No one doubts that we have been recovering fro the LIA for the last 160 years without the help of CO2 for at least the first 100."

Not only do I doubt it, I doubt the comment even means anything. That is because the key word is "recovery", and it is meaningless to talk about a recovery unless you can identify a ground state to which you are recovering. However, people who discuss the "recovery from the LIA" never identify that groundstate. Indeed, they insist the recovery was ongoing to the end of the 20th century even though end 20th century temperatures were likely higher than those of the Medieval Warm Period, a period of noteworthy and unusual global warmth, at least according to climate pseudo-skeptics. I have commented more on the purely rhetorical nature of the word "recovery" in this context elsewhere.

Not only do I doubt the "recovery" rhetoric based on its emptyness, however. More importantly it does not match what we know about global temperature trends.

I realized this due to a recent discussion I had about mean global temperature around 1750. The upshot is that mean global temperatures over the twenty year period centered on 1750 (1741-1760) are statistically indistiguishable from those centered on 1900, ie, there was no strong trend in mean global temperatures representing any "recovery" from the LIA.

arationofreason specifies the last 160 years, thereby restricting the timeframe to that covered by the instrumental record. Unfortunately for his hypothesis, the first 50 years of that record show a negative trend in GMST. Their "recovery" is actually an ongoing decline in GMST (see table in next paragraph), so that if we were to merely continue it, we would have had declining temperatures over the whole of the twentieth century.

Indeed, extending beyond the instrumental record, we see that there has been no recovery going back to the most intense phase of the LIA in the seventeenth century. Using Mann08 EIV global, we find trends as:

1616-1750 -0.097 C/century (Mann08)
1751-1850 0.000 C/century (Mann08)
1851-1900 -0.020 C/century (HadCRUT4)
1901-2014 0.768 C/century (HadCRUT4)

Clearly the "recovery" is a fiction of the imagination. Global temperatures declined from a peak around the 10th century AD (see graph) to a minimum around 1500 AD, from where they bumped around about the same level until after 1900, well after the start of industrial emissions of CO2.

So not only is the rhetorical appeal to the "recovery from the LIA" meaningless, it does not even get the facts about global temperature trends right.

CO2 measurements are suspect

Daniel Bailey at 01:30 AM on 24 June, 2015

"Can somebody please explain why only ice core data is used for the pre-instrumental measurement period"

It's not. Temperature measurements began in 1659. Stations were added throughout the centuries since then, becoming a truly global network beginning in 1880. Multiple proxy records extend that record literally millions of years into the past.

http://www.ncdc.noaa.gov/paleo/globalwarming/instrumental.html
http://www.ncdc.noaa.gov/oa/climate/research/1998/anomalies/anomalies.html
http://www.ncdc.noaa.gov/ghcnm/v3.php
http://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets
http://www.realclimate.org/index.php/data-sources/
http://en.wikipedia.org/wiki/Instrumental_temperature_record

Multiproxy reconstructions are now commonplace. For example, per the PAGES 2000 reconstruction, current global surface temperatures are hotter than at ANY time in the past 1,400 years, and that while the Medieval Warm Period and Little Ice Age are clearly visible events in their reconstruction, they were not globally synchronized events.

http://www.skepticalscience.com/pages2k-confirms-hockey-stick.html

From the peak temps and CO2 at the height of the Holocene Climatic Optimum some 7,000 years ago, temps and CO2 went into a long, slow decline, until about 100 years ago. Global temperatures dropped about 0.8 degrees C.

Over the past 100 years we have entirely erased that 5,000+ years of natural cooling (Marcott et al 2013), with global temperatures rising a full degree C:
http://www.realclimate.org/images//Marcott.png
http://climatedesk.org/wp-content/uploads/2013/03/marcott-B-1000.jpg
http://www.realclimate.org/index.php/archives/2013/09/paleoclimate-the-end-of-the-holocene/
http://www.sciencemag.org/content/339/6124/1198

Given that orbital forcing is still negative, and will continue to be negative for the next several thousand years, natural forcings are not responsible for this current warming period.

Please place relevant comments and questions on the pertinent thread.

It's El Niño

Tom Dayton at 03:04 AM on 1 June, 2015

Don Sage, for more insight to the errors (and "errors"--ahem) in Don Easterbrook's claims, see Dana's other Easterbrook post, "It's PDO," "It's the Sun," and "Climate's Changed Before." Many Skeptical Science posts have Basic, Intermediate, and Advanced tabbed panes; read them all. Also, be sure to post comments only on the relevant threads. You can monitor all comments on all threads by clicking the "Comments" link in the horizontal blue bar at the top of every page.

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