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

Eclectic at 15:33 PM on 3 April, 2024

Jimsteele @83 :

Certainly the ocean skin surface is the gateway through which heat enters & leaves the ocean. (Other than the large flux of solar radiation which penetrates deeply into the ocean ~ we scuba divers can definitely see that occurring ! )

But as I mentioned above, the skin surface dynamics do not disturb the long-term equilibrium of energies, over the course of days and years. Surely that is obvious to you. Please do not confuse & distract yourself with the ephemeral fluctuations in the surface few microns of oceanic water.

Also ~ do not distract yourself with thinking about the different heat fluxes in the tropic / temperate / and polar zones of the planet. Those zones have their own long-term equilibrium positions, and their existence (and fluctuations) won't change the medium-term equilibrium of the total planet.

Second ~ please educate yourself about the paleo history of Earth . . . and its "iceball" phases. Yes, the paleo evidence indicates low armospheric CO2 produces "iceball" oceanic freezing. In addition to that evidence, the basic physics of Earth's planetary orbital distance and the incident solar radiation on Earth . . . indicate that the Earth's oceans would become meters-deep in ice, if the atmospheric "greenhouse" effect were to disappear.

Jim ~ you would lose all scientific credibility if you assert that the so-called greenhouse effect does not exist. Please step back from the brink . . . and reconsider your position.

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

Doug Bostrom at 03:27 AM on 28 March, 2024

There's a lot of "inside baseball" language in play involved with meta-climate discussion, Two Dog.

"Climate change denial" seems to have become shorthand for "climate science denial" and "climate change denial." Both phenomena have rich factual basis.

There is still to this day a shrinking population of folks who don't believe Earth's climate and climate-mediated systems are changing at what current and paleoclimate data indicate are unusually rapid rates. This would be "climate change denial" as labeled on the tin.

Meanwhile another population are focused on what is still slightly more fertile ground, that of calling into question the scientific community's (geophysicists in this domain, specifically) competence of understanding the controlling processes of Earth's climate. This is "climate science denial.'

While often uttered in a context of emotional heat and frustration, "climate change denial" and "climate science denial" are not fundamentally emotive but rather are descriptive language attached to facts.

Both species of denial face what will prove an insurmountable common challenge: consilience. By example, biologists are observing phenonena that would demand answers from geophysicists focused on Earth's climate systems. As it happens, geophysicists already had substantially useful explanations for what biologists are seeing in the natural world. This is retail level consilience. One of the purposes of our weekly climate-related academic research listing is to help people to see consilience on anthropogenic climate change, understand the overall perspective of experts having connection to matters influenced by climate— which includes numerous disciplines not directly connected with geophysics.

if one follows climate research output and its present concerns, it's plain to see we're quite far past the "huge unknowns" stage with respect to the geophysics of climate. The accidental perception of "huge unknowns" in climate geophysics is a mark of the success of climate science deniers in the public square. It's a product of what we might clinically term "synthetic ignorance," a feeling of not knowing what we actually know perfectly well enough, thanks to calculated practice in public messaging.

Is every stripe on every graph we see 100% about us? No. Certainly the climate change we see today is influenced by "natural variation," on the time scale we're concerned with a matter of dithering around a mean. However, numerous and broad secular trends we're seeing not only in direct geophysical attributes of climate but myriad other features having climate as a major controlling variable find reliable explanation and predictive power in one naturally evolved feature of Earth, namely the planet's human population and culture— and how we've powered ourselves by liberation of energy from fossil fuels. We can hypothesize elaborate mechanisms for system-wide changes of the type we're seeing but scientific parsimony asks "why invent where no invention is necessary?" The dominant rationale for such invention seems to lie outsiide of scientific practice.

As to greening, greening enthusiasts should note that this phenomenon is accompanied by loss of albedo for a variety of reasons. Loss of albedo is not something we need at this juncture. It's also notable that for "climate change deniers" of all stripes, greening is a powerful contradiction of the basis of preferred beliefs.

At a glance - Is the CO2 effect saturated?

Just Dean at 09:44 AM on 11 January, 2024

I think this is where data from paleoclimatology can help as well. Three recent studies have looked at the earth's temperature vs CO2 during the Cenozoic period, Rae et al., Honisch et al., and Tierney et al. . Each of those show that the temperature of ancient earth continues to rise as CO2 increases. As I understand it the first two are based solely on proxy data while the Tierney effort includes modeling to try and correlate the data geographically and temporally.

All of these are concerned with earth system sensitivities that include both short term climate responses plus slower feedback processes that can take millenia, e.g. growth and melting of continental ice sheets. Both Rae and Honisch include reference lines for 8 C / doubling of CO2. In both cases, almost all the data lie below those reference lines suggesting that 8 C / doubling is an upper bound or estimate of earth's equilibrium between temperature and CO2. Also notice that there quite is a bit of spread in the data.

In contrast, when Tierney et al. include modeling they get a much better correlation of T and CO2. They find that their data is best correlated with 8.2 C / doubling, r = 0.97. Again, this represents an equilibrium that can take millenia to achieve but does to my way of thinking represent "nature's equilibrium" between T and CO2.

In these comparisons, the researchers define changes in temperature relative to preindustrial conditions, CO2 = 280 ppm. For Tierney's correlation then on geological timescale, the temperature would increase by 8.2 C at 560 ppm. At our present value of 420 ppm there would be 3.7 C of apparent warming potential above our 1.1 C increase already achieved as of 2022, i.e., global warming in the pipeline if you will.

Bottom line, based on paleoclimatological data, there is no apparent saturation level of CO2.

Skeptical Science New Research for Week #26 2023

Just Dean at 07:26 AM on 2 January, 2024

Eclectic @10.

I have been following Dr. Tierney's work for sometime. I think Dr. Tierney's work is underappreciated. I think the combination of proxy data with modeling is cutting edge for paleoclimatogy. For instance, I think her paper in Nature with Osman may ultimately redefine the shape of the "hockey stick," REF .

Also, look at the quality of the fit for the Cenzoic age, this research really might start to constrain the climate models for predicting future temperatures for different emission scenarios.

Skeptical Science New Research for Week #26 2023

Eclectic at 05:14 AM on 2 January, 2024

Just Dean @9 :

Thanks for the J.Tierney video reference [not yet viewed by me].

I note the name Osman listed in the video credits, and also note that the video is marked as having had 135 views in 2 months. So, not yet setting the the world on fire [apologies to Secretary-General Guterres of the U.N.].

Just Dean ~ broadly speaking, the paleo record conforms with the present-day understanding of the climatic actions of CO2. Is there a special point that you are wishing to make, regarding the paleo climate?

Skeptical Science New Research for Week #26 2023

Just Dean at 08:32 AM on 1 January, 2024

I was looking for recent articles on paleoclimatogical data for CO2 vs Temperature and happened to this posting about the work of W. Jackson Davis. Based on a previous work of his claiming that CO2 concentrations did not cause temperature changes in ancient climates, REF , I would definitely advise caution when considering his works.

Skeptical Science New Research for Week #49 2023

nigelj at 04:35 AM on 10 December, 2023

MS Sweet. Good information to know.

"I note that Dr. Hansen has long held an Earth System Sensitivity of 6 C. The IPCC consensus has been 3C"

The IPCC number is "equilibrium climate sensitivity", a different thing from earth system sensativity as below. Making it hard to compare the two numbers.

"By definition, equilibrium climate sensitivity does not include feedbacks that take millennia to emerge, such as long-term changes in Earth's albedo because of changes in ice sheets and vegetation. It includes the slow response of the deep oceans' warming, which also takes millennia, and so ECS fails to reflect the actual future warming that would occur if CO2 is stabilized at double pre-industrial values.[38] Earth system sensitivity (ESS) incorporates the effects of these slower feedback loops, such as the change in Earth's albedo from the melting of large continental ice sheets, which covered much of the Northern Hemisphere during the Last Glacial Maximum and still cover Greenland and Antarctica)...."

(Climate sensitivity, wikipedia)

We will probably never know any of these numbers for sure because you can't put the planet in the laboratory. (Although I think paleo studies like the one you posted have a lot of credibility - because they are based on real world conditions). But IMHO that uncertainty is not necessarily a crucial problem. Current rates of warming are bad and are having very visible effects, and huge implicatrion in the short to medium term, and so whatever the level of climate sensitivity using whatever definition, we clearly have a huge problem.

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

Rob Honeycutt at 02:09 AM on 29 October, 2023

TWFA... "The climate would and will continue warming at this phase even if man never existed..."

Here, yet again, you literally have no clue what you're talking about but present something as if it were fact.

If you look at the paleo record it is very clear that the Earth was entering a cooling phase due to slow changes in orbital forcings. It's only when humans started burning fossil fuels and substantially altering surface albedo (deforestation, farming, etc) that the planet abruptly changed and entered a steep warming trend.

Real Climate, Marcott 2013

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

Rob Honeycutt at 12:24 PM on 27 October, 2023

TWFA... "...because the effects of cloud cover and weather is my primary area of interest I would appreciate links to that data."

Aside from your childish passage prior to this ask, there is a full body of research on cloud effects on climate. Perhaps you should endeavor to read the research instead of just assuming a preferred position.

One key clue that cloud effects aren't going to save us is merely the fact that, over the past million years we can see (through all kinds of paleo records) that the earth has gone through numerous glacial-interglacial cycles. We know the pacing and forcings that drive those cycles.

So, think about it. If cloud/weather effects were capable of offsetting changes in modern climate forcings, why would it not have done so over the past million years?

If what you're assuming were true, then we'd see no climate cycles because clouds/weather would always keep global temperature in equilibrium.

Ice age predicted in the 70s

Bob Loblaw at 23:05 PM on 16 August, 2023

Don:

@114:

You have not specified what you think are the two sides implied by your "both sides" quip.

If you are going to be condescending about throwing out Michael Mann's name, your credibility is going to go to zero. Without a statement explaining what you think "both sides" means, then providing names is meaningless.

It is not the label "Geology" on Mann's PhD that makes him a climatologist. It is the nature of the work that he did (paleoclimatology) and what he has done since. It appears that you would rather obfuscate, than clarify.

@ 115:

Let's look at Oreskes' exact words in the last paragraph of her introduction:

If scientific knowledge can be characterized as the convergence of expert opinion, then this kind of abrupt reversal of opinion might undermine our confidence in that knowledge, unless we can give a convincing account of the empirical reasons behind that reversal, and the historical context in which those reasons became persuasive.

Since sarcasm and condescension seem to be the kind of discussion you want to have, please note Oreskes' use of the word "might". In case you are unfamiliar with the word, it means "possibility". It is a conditional statement, and the condition is "unless we can give a convincing account".

The simple fact is that we do have information about why old viewpoints regarding the cooling of the earth on geological time scales transformed into an expectation that CO2 would lead to warming. And Oreskes' paper discusses this.

You appear to want to make a mountain out of a molehill.

2nd law of thermodynamics contradicts greenhouse theory

Rob Honeycutt at 14:24 PM on 13 June, 2023

Bob... There's also a very weird part of the Davis paper where he goes on at length explaining the non-linear aspect of GHG forcing, as if anyone reviewing or reading the paper wouldn't already understand that. In a paper on paleoclimate that aspect should get one sentence and maybe a reference and be done with it.

I'm not conviced this is an actual peer reviewed paper.

CO2 lags temperature

Daniel Bailey at 01:46 AM on 19 May, 2023

For a longer view of the correlation between CO2 concentrations and global temperatures, look no further than this reconstruction of the past 540 million years of such from Scotese (Scotese 2021 - Phanerozoic paleotemperatures: The earth’s changing climate during the last 540 million years):

CO2 and temperatures the past 540 million years

Link to paper

Link to uploaded graphic

And leaving the last word on the subject to Scotese, a true expert in the field:

"It has been long recognized that the Earth’s climate, in particular the average global temperature, has alternated between ”icehouse” and “hothouse” states. More than 70 years ago, studies recognized that these climatic “modes” varied on short-term, medium-term, and long-term timescales. During the past 20 years, due to much outstanding research, we now stand at the threshold to a deeper, more complete understanding of both the tempo and mode of global temperature change during the Phanerozoic.

The Earth’s long-term temperature change is controlled by multiple tectonic and environmental processes that drive the Earth’s climate from icehouse to hothouse conditions, and vice versa. Many of these factors are interconnected by a complex network of positive and negative feedback loops that can accelerate or decelerate changes in long-term global temperature.

We are currently about halfway through a typical glacial/interglacial cycle. If humans did not inhabit the Earth, about 20,000 years from now, global temperatures would have once again begun to fall and ice sheets would have expanded into the oceans surrounding Antarctica and would have descended from the Arctic to begin a slow and steady march across the northern continents. However, this will not happen. The Earth has entered a “super-interglacial”. The injection of CO2 into the atmosphere as a consequence of the burning of fossil fuels has warmed the Earth more than 1°C and will continue to warm the Earth for another 300 years (~2300 CE).

In conclusion, we are leaving our Ice Age heritage behind. A new, warmer world awaits us. The problem we face is not so much where we are headed, but rather how we will get there."

CO2 lags temperature

Bob Loblaw at 23:27 PM on 18 May, 2023

Ron @ 648:

I am not sure exactly what you are looking for, or what you want to compare. The post here (check out all three of the basic, intermediate, and advanced tabs, plus the extra information that is posted below the comments) talks about some of the complexities of comparing ice core CO2 data to temperature. There is also a good post here at SkS about ice core data.

Ice core "temperature" is not global - it's more local or regional, as it is based on oxygen isotope ratios in the core. This is affected by the temperature at which the precipitation is formed. See this page or this page for more details. When comparing CO2 and temperature, careful consideration of the source of temperature data is needed in order to assess the meaning of the comparison. In addition, estimating age in ice cores involves complexities of glacial flow, how long it takes gas to get trapped, etc.

The figures you link to do not mention the data sources used. The OP here lists some data sources, but unfortunately it looks like some of the links are broken. A quick search finds sources for Dome C data here and here. Those pages include links to other pages, graphs, and original studies. Depending on just what sort of comparison you are trying to do (especially if it is statistical), you may be best off finding original data and making your own graph. At least then you know exactly what data you are getting.

The Intermediate tab here also has a section pointing out that later studies have revised some of the timing interpretations of the ice core data. Read down to section 4 "This myth is based on old data".

The Big Picture

Eclectic at 14:39 PM on 19 March, 2023

Gootmud @100 ,

you are right that shutting down the old reliable (fossil fuel) power sources is premature, pending the establishment of a fully resilient new renewables and/or nuclear power system. That's simply common sense. Just as it's simply common sense to press ahead rapidly to achieve "Zero Nett Carbon", even though that will take decades to complete the transition.

But you are in the wrong, to think that "models" are vital (or even mildly important) in making a sensible pragmatic assessment of the climate situation. For example, back in the 1890's [not a misprint] a scientist was able to make a reasonable assessment of what happens as CO2 atmospheric level increases. All he needed to use was a pencil & paper [not a model or a computer in sight]. Granted, he had a better brain than me (and possibly than you, too). He was not in any way dependent on complex "models". Nor, using common sense, do the conclusions of climate scientist of today need more than basic physics ~ helped along by paleontological knowledge of Earth's climate history.

Economics ~ yeah, not really much of a science. Too much Friedman and freedom from common sense.

The Big Picture

Rob Honeycutt at 00:54 AM on 18 March, 2023

Peppers @36... Do you honestly need me to explain why you can't just take historical sea level rise data, run a straight line through it, and extrapolate sea level in 2100? This is basic enough that it might be a challenge to find citations. How about you make a guess and we'll see if you can work out why and perhaps, from that, we can help you understand why SLR projections show 1-2 meters for 2100.

I'll even get you started: Think about ice.

This is also wrong: "66M years ago we had the meteor strike, and the world went dark under dust for 3-4 years. Everything died, except the microorganizms around the rim of the oceans, around the world."

Though it is off-topic, it's a good demonstration of how you're simply making things up as you go along. In the Cretaceous–Paleogene extinction event about 75% of species went extinct. We are direct decendants of small mammals that survived the event.

Most of the rest of what you state there is also BS (for instance, much of the world's oil actually originates from the Cretaceous and Jurassic periods, not just the Tertiary period following the C-P event) but I'm not going to waste my time.

The Big Picture

peppers at 00:18 AM on 18 March, 2023

HI Rob!

Do you have cites for your 'abundantly obvious reasons?", Thx

One Planet, huge effort and thanks for it!

In that rise in population from 1B to 8 B ( Im going to use 1900 to present, although 1B was in the 1800's), the USA rose from 76.3M to the 335M now. China went from 336M to 1.3B, and so on. The world gained porportionally and if a household used blank amount of energy, it increased 5 fold in the US in quantity and so on. The new population was not all in low production regions.

I am minded of the basic business principal of the 3 terms, reduce outgo, increase income (per unit), and doing more of it. The doing more of it is the mark of the run away businesses. I would not dilute the 800% rise in population with trace factors, to not tell yourself the truth that population, the 'more of it' is the core of this issue.

And it is important. Because if one realizes this, you can consider if this is in the solar system's realm of inevitibles rather than in our hands. I mean, the sun is moving 828k/hr around the milky way, we are orbiting 18.5 miles per second around the sun, and all the countless other intricacies of our solar system which would be folly to address. Might be dangerous even...

Its a question, as Rob poses above, of doing the best we can. He says what is being done is at least stemming the flow. I disagree, but if population is the cause we may be better oriented to aid in adaptation to the changes. Nothing really is wrong and there is no reason to fear a runaway cycle as the cause is not mysterious then.

Nasa concludes more warmth likely adds more energy to the environment, but they do not know if, how much or where. I would think it does add. But what of it is my mext question. The problem is addressable in the quality of our shelter.

Hurricane Dorian was the largest in 84 years ( an example on the Nasa Site), so it matched one as large before the industrial revolution was in great effect. Nasa's point it, its still a guess.

But Florida level of sheltering, where 150 died in 200mph Ian last Sept, was better than the 200k who died in crumbling buildings in Syria. Thats what we can put hands on, to aid in this issue.

https://climate.nasa.gov/ask-nasa-climate/2956/how-climate-change-may-be-impacting-storms-over-earths-tropical-oceans/

I would like to add one more mode of thought, which I dont see addressed here much. And it is only remote, so please do not categorize me as conspiracy oriented. My thoughts are how we best use our hands and feet on this. Not whether the problem exists.

But I find this interesting.

66M years ago we had the meteor strike, and the world went dark under dust for 3-4 years. Everything died, except the microorganizms around the rim of the oceans, around the world. The myth is that oil deposits are decomposed dinosaurs, but really it it the rotted countless trillions of these happy cells which had a heyday for a millions years with no other competition for the enriching co2 and oxygen in the environment. These tiny crustaceans died with the oxygen in its calcium and sequestered away ox as well as co2, of which these 2 chemical elements are bossom brothers.

As such, an inordinant amount of oxygen was also captured and the current level of oxygen dimishment has us at about 900 feet altitude now compared to sea level saturation back then. Saturation is going down and the equivolent as altitude is increasing.

Forbes: Air bubbles trapped within ice provides clues to the atmospheric composition at the time of "deposition" and can be analyzed for paleo-oxygen levels. The study finds that over the past 800,000 years the amount of oxygen found in the atmosphere has decreased by 0.7% and continues to decline.

I think it is something like 14M years before oxygen reaches where we would need masks to visit the beach, so this is a mild bit of input on this supercharged forum.

But what is the solution to this? More weather and rain is needed to wash the shells with all this captured oxygen back in to the oceans, to restock the active environment with the element.

Do we know what we are doing to pick any possible cycle of earth or the solar system itself, and interfer with all these conclusions and guesses. Why is it not prudent to ask these questions?

I dont think it is invasive to make umbrellas, levee's, bunkers and warm towels!

Thanks everyone, D

IPCC overestimate temperature rise

Eclectic at 00:02 AM on 10 January, 2023

Pbarcelog @67 ;

Probably best to look to whatever underlying point your engineer friend is trying to make. Just as hurricane statistics vary considerably over decades, so too does snow cover vary ~ but neither of these measurements do "disprove" the major global warming observed.

It seems he is trying to cherry-pick one or other of whatever observations he can find, which . . . what? . . . show there is no warming and therefore no human-caused effect on climate? If that is his game (to convince himself at some emotional level of "no AGW") . . . then he is simply failing to look at the big picture. He is deceiving himself. And he is also failing to look at the paleo evidence of major climate changes produced by alteration in greenhouse gasses.

Does he have Conspiracy-type doubts that the past 170 years of thermometer measurements are all false, and all the climate scientists are wrong? If the planet is not warming, then why is the sea level continuing to rise?

He may feel that 0.2 Watts or 1.0 Watts is a tiny number . . . but the evidence keeps showing that the world is warming ~ whatever his (rather ill-informed) opinion might be about clouds.

The warming effect of increased CO2 level is only denied by the nuttiest of non-scientists ~ and they have zero evidence to back up their ideas of "no greenhouse effect". The effect of CO2 has been known for roughly a century. Basic physics explains it, and decades of observations confirm it.

(Please note that laboratory experiments cannot re-create the necessary full-depth atmosphere that produces "greenhouse" . . . so I have not bothered to review the "Backscatter Radiation" experiment you touched on ~ but if you feel there is something of great note & importance demonstrated in the experiment, then please discuss it in more detail, and preferably with a direct link to the paper.)

Skeptical Science New Research for Week #52 2022

MA Rodger at 20:45 PM on 5 January, 2023

michael sweet @4,

This document 'Global warming in the pipeline' by Hansen et al does appear to need some rewriting in my view.
It explains it is the first of a pair (the second being 'Sea Level Rise in the Pipeline') and together they are perhaps akin to Hansen et al (2016) 'Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous' which was more a discussion document than a piece of science. But given 'Global warming in the pipeline' starts off with our understanding of the greenhouse effect back in the 1800s, its audience is probably not climatologists, so not a discussion document, although it does get a bit 'detailed' in places where a good understanding of climatology is required.

At 48 pages, it covers a lot of ground and as-yet I haven't read very far through it, down to page 12 which covers the assessment of ECS. But it does read a little odd.

The Abstract tells us that "improved knowledge of glacial-to-interglacial global temperature change implies that fastfeedback equilibrium climate sensitivity is at least ~4°C for doubled CO2"

The first thing that I felt odd was reference to Hansen et al (1984) 'Climate sensitivity: analysis of feedback mechanisms' but without a sign that this was such an old paper. The tempersture rise from the LGM used to calculate the ECS in Hansen et al (1984) is said to be +3.6°C, a value said to yield ECS=2.5 to 5°C. For me, that +3.6°C temperature increase is way below that usually quoted elsewhere for the post-LGM temperature rise.

And 'Global warming in the pipeline' indeed then presents higher estimates of the temperature rise from the LGM: +6.8°C (± 0.8) in Osman et al (2021), +5.9°C (± 0.3) in Tierney et al (2020) and +5.8°C (± 0.6) for land SAT from Seltzer et al (2021).

These are in keeping with values I've seen in literature for recent decades which usually sit +5°C to 6°C, perhaps the +6.8°C (± 0.8) in Osman et al (2021) a little higher than normal while some of those lower values have also persisted.

And using such LMGR temperature increases, 'Global warming in the pipeline' then calculates ECS concluding "Thus, while the LGM-Holocene climate change implies ECS =3.3-5.1°C for 2×CO2, the PGM-Eemian implies ECS ~ 4-6°C. We conclude ECS is at least approximately 4°C and is almost surely in the range 3.5-5.5°C."

What goes unsaid is that the literature used to source LGMR the temperature rise from the LGM also developes ECS values with ECS = 2.2°C to 4.3°C in Tierney et al (2020) (Fig 4 from this paper below, the R_AE accounting for 'mineral dust forcing') with Seltzer et al (2021) concurring with the central value of this, 3.4°C. For 'Global warming in the pipeline' to ignore these ECS values is entirely unscientific as we now have two values for ECS derived from LGMR which are at odds with each other.

Tierney et al (2020) Fig 4

And the use of the PMG-Eemian temperature rise to calculate an ECS value is a novel and perhaps rather too adventurous as I don't know of such a use previously. 'Global warming in the pipeline' references Rohling et al (2017), a long paper which does not itself address ECS.

So that is not a good start for a work which presents such startling findings.

Skeptical Science New Research for Week #52 2022

michael sweet at 09:48 AM on 3 January, 2023

Hairy BUtler,

I read the Hansen et al preprint and Manns response. THe Hansen paper is long and technical. To evaluate the claims is beyond my pay grade, but I can summarize Hansen's claims.

1) Hansen et al claim that studies of Paleoclimate (the climate in ages past) are the best way to estimate climate sensitivity. The current estimate of the Charney equilibrium climate sensitivity (ECS) is 3C per doubling of carbon dioxide. The ECS is the equilibtium temperature from rapidly changing thngs like atmospheric temperature and the ocean surface. It has been 3C for a long time. Recent papers have made new estimates of the last glacial maximum (LGM) global temperature that are about 3C lower than older estimates were. This results in the ECS increasing to about 4 or 5C. Mann cites the old papers to contradict Hansen. If the ECS is really 4C instead of 3C than the expected warming is significantly greater. Scientists often argue about whether or not new estimates are correct. This can take years to resolve.

2) Hansen has felt for decades that aerosol effects on climate have been underestimated. Hansen claims that current Global Climate Models (GCM's) overestimate ocean mixing and underestimate aerosol cooling effects. He provides new data to support this claim. The net effect is to lower the calculated ECS. As more and more energy comes from renewable sources the amount of aerosols in the atmosphere will decrease. Since aerosols cool the Earth the net effect is greater warming than we have already experienced.

3) Hansen defines the Earth System Sensitivity (ESS) as the final temperature reached when slow responding functions like the melting of global ice caps reach final equilibrium. This is significantly higher than the ECS, perhaps as high as 10C per doubling of carbon dioxide. The generally accepted wisdon is that ESS will take thousands of years to reach equilibrium. Hansen argues that It will be much faster. Perhaps as much as 80% of final heating in a centuary.

4) The net effect of higher ECS and ESS combined with higher aerosol effects means that there is a lot more heating in the pipeline (heating caused by carbon dioxide already in the atmosphere) than is currently believed to be the case.

5) Since Hansen expects warming to be greater than the current consensus, much more heating is already in the pipeline and that it will happen much faster than currently expected, he argues that governments need to act much faster to contain this emergency as soon as possible.

Hansen has made the argument for many years that aerosols are underestimated, ESS is higher than the current consensus and more warming is in the pipeline. He has new data in this paper to support his claims. This paper claims that the much more rapid increase in temperature he predicts will be obvious by 2050 and strong indications of his predictions will be measured in about 10 years.

Mann basically says that he doesn't buy Hansens' argument. Hopefully Gavin Schmidt at Real Climate will write a summary that will tell us the consensus view of what Hansen thinks is new data. I expect Dr. Schmidt to agree with Dr. Mann. I cannot evaluate Hansens claims, it is too technical.

In my view, Hansen is a great scientist who has been correct several times before when he stuck his neck out. He has also missed the mark on occasion. It is worrysome to have someone so talented make such a grim argument. This argument is not that different from his previous position but it has some new data to support his case. I imagine that this paper will be discussed a fair amount online but that the IPCC consensus will not change until it is 2050 and his forecasts have proven correct. Pray to whatever Gods you have that Hansen is incorrect.

If anyone else reads Hansen et al I am interested in your thoughts and/or additions on what I have posted here.

Temp record is unreliable

Bob Loblaw at 22:39 PM on 27 September, 2022

To follow up Eclectic's comment at 525, there are many environmental/geological records that indicate various features of past climates. Vegetation and animal populations are often linked to local climate, and fossil evidence of past vegetation and animal abundance gives indications of past climates.

Tree rings go back thousands of years in some cases, and fossil trees can generate longer tree ring records - earlier than the oldest living tree in the area.

Pollen deposited in lake sediments indicates vegetation at the time the sediment was deposited. In many areas, the lake sediments have annual layers due to summer/winter variations in hydrology, so the layers are easily dated. Thickness of layers gives indications of rainfall/stream flow variations that affect the amount of sediment.

Eclectic mentioned ice cores, which can give both temperature information and atmospheric gas concentrations (CO2) going back hundreds of thousands of years.

A search here on "proxy" yields a couple of useful posts:

https://skepticalscience.com/Peter-Brannens-Paleo-Proxy-Twitter-Thread.html

https://skepticalscience.com/Tai-Chi-Temperature-Reconstructions.html

Wikipedia has some discussion of the "Hockey Stick"

https://en.wikipedia.org/wiki/Hockey_stick_graph_(global_temperature)

Unless your friend knows details of the "reliability" of these many methods of examining past climates, he/she is arguing from a position of lack of knowledge.

What’s going on with the Greenland ice sheet?

MA Rodger at 23:09 PM on 3 September, 2022

Wayne @4,
I was in two minds on continuing our interchange, but I decided I would continue when I came across coverage of the paper underlying this SkS OP which surprisingly appeared today on the pages of my local rag with the title "Zombie ice to raise global sea level". On-line I see the same story getting into newspapers elsewhere (eg The Washigton Post).

In terms of an SLR-CO2 correlations, I don't recall seeing Hansen provide it. I believe the closest he got was in Hansen et al (2013) 'Climate sensitivity, sea level and atmospheric carbon dioxide' (with its well-used Fig 1) which looked at temperature & SLR but only inferred CO2 levels with very cursory checks to actual CO2 reconstructions.

Hansen et al (2013) fig 1
And for me, Hansen's 5m SLR by 2100 was always a bit of theorising that I struggled with. Even after it appeared properly written up in Hansen et al (2016), which at least answered the energy equations that were my initial objection to such a large SLR projections, for me it still remains more 'discussion document' than a full-blooded argued case. In my view, worrying as it is, the future SLR from Greenland & Antarctica depends on the Precipitation minus Ice-Loss balances and that puts us in the hands of climatologists for the precipitaion and glaciologists for the ice-loss. The application of paleoclimatology and whether Greenland melted out in the Eemian isn't so relevant for our future SLR.

Just to throw in my other SLR bug bear which also becomes relevant here, I've always reckoned SLR ain't gonna stop at 2100. So why do we go on so long about the 2100 SLR when by 2150, 2200, 2300 etc it's going to be seriously bigger? (A total of 2.3m SLR/ºC AGW according to IPCC AR5 fig13.14.)

The SLR-ΔCO2 relationship is of course a paleoclimate thing, so may not be immediately relevant outside the Eemian or now we have a Panama Isthmus connecting N&S America. That said, the SLR-ΔCO2 relationship is usually a step beyond what most graphics provide, but fig 6 of Rea et al (2021) 'Atmospheric CO2 over the Past 66 Million Years from Marine Archives' does provide us a ΔT-SLR-ΔCO2 graphic. Note that they do not attempt to be definitive with this CO2 reconstruction, saying "While each method has uncertainties, these are largely independent, so their broad convergence on similar CO2 histories is encouraging."
Rea et al (2019) fig 6

But I stress the idea that paleoclimate stuff should concede precedence to glaciology when it comes to the melting ice caps today and glaciology is where the paper underlying the SkS OP above comes from, Box et al (2022) 'Greenland ice sheet climate disequilibrium and committed sea-level rise'. I read that paper as saying that, as of now (2000-19), Greenland is not tipped over into melt-out mode (which I think was always seen as requiring a little more AGW to do that tipping, but nonetheless is good news to hear said) and that the Greenland melt which we are committed-to will happen in the next several decades, not several centuries, and will be mainly over by 2100.

So at least for Greenland under the AGW so-far, my bug bear (that we are in denial ignoring massive SLR awaiting us post-2100) is assuaged.

Mind, the SLR thus awaiting from Greenland isn't trivial. And there is still Antarctica. And not forgetting we still have the tiny task of halting future AGW.

Clouds provide negative feedback

Eclectic at 04:50 AM on 13 July, 2022

Likeitwarm @26 :

Yes, it seems cooler on cloudy days than sunny days ~ during daytime.

But warmer nights, when it is cloudy.

Overall effect, rather close to neutral.

The paleo evidence shows no "runaway" , but it does show that the global climate can become very hot indeed.

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.

Addressing the Climate Crisis: ~~Evolution or~~ Revolution¹

swampfoxh at 22:27 PM on 6 March, 2022

Eclectic

I had in mind: The collision between emissions producing a somewhat higher than 3.0C, the terrestrial damage already, and yet to be done, and the size of the global population will winnow itself out in a general catastrophe similar in scope to the very early End Triassic or perhaps the early End Paleocene extinction events. The population is likely to fall back to around 500 million which removes both the GHG emissions problem and the terrestrial damage events fostered by human activity over these past 200 years.

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

nigelj at 16:47 PM on 21 February, 2022

Santalives @80

I already said what I think drives people over at WUWT @74. I've amended it slightly here. Imho denialists seem to mostly engage in a lot of deliberate stupidity, mixed together with political and ideological motives (often libertarianism) , motivated reasoning, cherrypicking, and a tendency to see conspiracies everywhere. However some just appear naturally quite stupid (eg: JDS over at realclimate.org). There are also the scientific cranks with science degrees who just seem to like to be different and become very stubborn and narcissistic. This is my observation. I suspect you wont like this but its how they all frequently come across to me.

Regarding "Rethinking Climate, Climate Change, and Their Relationship with Water by Demetris Koutsoyiannis"

Some of his discussion is interesting and colourful. However a discussion of how to better define climate doesn't much interest me. I said before its pedantry. In no way does such a thing directly relate to or undermine findings that humans are causing a warming effect. And what we are interested in is relativities and rates of change from one period to another. You do not need a precise and perfect definition of climate to measure that. I'm sure you would get what I mean. I haven't the time to study his maths in detail and I'm rusty on some of that but I'm sure its probably correct, but it isn't relevant to the points I've just made. He himself said people will probably regard his paper as useless!

He then goes into a long discussion about water: "This idea is further expanded to establish a linear causality chain of the type: human CO2 emissions → increasing concentration of atmospheric CO2; → increasing temperature → changes in hydrological processes and water balance. This is evident in the popular practice of studying the so-called climate change impacts on hydrological processes. However, this is a naïve idea that does not correspond to physical reality.........Arguably, the fact that the CO2; has been so heavily and repeatedly studied, particularly in paleoclimatology studies (e.g., [49,51,52,53,54,55,56,57]), does not suggest that it is more important a greenhouse gas than water. Here we argue that water is the most crucial element determining climate (e.g., [58,59]), or as put by Poyet [60], “Water is the main player”. We list epigrammatically some of the reasons justifying it: (Abundance, heat storage etc.)"

The fact that water is abundant and a heat store and can be influenced by changes in solar energy and that water vapour is the more abundant a greenhouse gas is not contested or new information, and obviously does not in any way undermine the conventional idea that changes in Co2 is causally linked to increased evaporation which can cause further warming. He has conflated things, and enaged in a logical fallacy by deliberate intent or lack of awareness.

He has to be able to explain how his own theory of water would explain climate warming over the last 100 years. He provides no evidence based causal link to expalin a change in water vapour levels in the atmosphere over the period. But Co2 causing warming and evaporation and further warming explains things perfectly well and is consistent with the evidence.

Don't ask me why, how or when on all the details. I don't have the time for more. I'm giving you the essentials as I see them. To me its all fairly obvious. Think about it. I'm just an interested observer and while I enjoy discussions I dont have all day.

The 1.5 degrees goal: Beware of unintended consequences

DK_ID at 08:12 AM on 16 January, 2022

Hal @8, I think you may be looking for where the GHGs came from before the Industrial Revolution. The GH effect is necessary for life on Earth. Our black body temperature would be 34 deg C lower than the current avg T---too cold for liquid water, hence no life. Carbon is emitted by volcanos, which currently produce about 1-2% of our emissions annually, and converted to limestone by weathering of silica based rocks. You are correct that paleo-agriculture increased CO2. From around 5000 years ago to around 1790, our ancestors increased CO2 back up to where it was at the last climate optimum (280 ppm). Since then, the rise to 420 ppm has been mostly from the burning of fossil fuels.

It's not bad

Eclectic at 19:07 PM on 16 July, 2021

TVC15 @390 :-

Permit me some general waffle : my comment is that you should be half'n'half ~ half optimist, half pessimist. The global situation is going to get bad but not catastrophic. Yes, we are going to blow straight past the 1.5 degree mark in global surface temperature rise since pre-industrial. The rise already (over 170 years) is about 1.1 degrees, and this makes a mockery of any contrarian who opines that the CO2-doubling Climate Sensitivity is less than roughly 2.0 degrees (and seems most likely to be in the 2.5 to 3.0 degree range at equilibrium ~ which also fits with non-historic data e.g. the paleo data).

With extraordinarily good management, we might conceivably halt the rise by 2.0 degrees . . . but our political track record so far is poor.

It is not just the politics, but technological advances which are still required. Sure : cheaper solar & wind technologies are coming, but we really should have started seriously developing these at least 10 years before we actually did. (But the past cannot be changed.)

The 2050 date for "carbon neutral" will require more than the present-day solar & wind, even at half of today's prices. Energy storage is absolutely necessary ~ and I am looking to bulk storage of electrolytic hydrogen. Hydrogen to provide electricity via fuel cells (at small scale) or steam-driven turbines at large scale (possibly combined-cycle?).

The second leg to stand on, is a hugely-increased supply of liquid hydrocarbon [octane / kerosene / diesel types] produced from non-fossil feedstocks, by means of catalytic / enzymatic / fermentational technology. In brief, we need to produce these hydrocarbons at a scale little short of present-day fossil fuel consumption. For a great amount of our energy usage, these hydrocarbons are necessary ~ and I suspect it will take many decades after 2050 , before we could replace such hydrocarbon fuels.

Extinction of a very large slice of animal/plant species . . . is arguable. Extinction of the human race ~ certainly impossible. The casualty rate may be high in the future ~ but extinction, no way. Mass migration of "climate refugees" will increase as sea level rise and heat waves occur, and there will be major social disruption. "Interesting Times" , as the old Chinese saying goes.

Climate's changed before

MA Rodger at 00:21 AM on 14 July, 2021

TVC15 @873,
Your denialist is actually making four bold statements that are patently nonsense with the rather pathetic request that you "Tell us why this Inter-Glacial Period should be different."

"Ice sheets and glaciers always melt during Inter-Glacial Periods." The melting actually happens in the run-up to the "Inter-Glacial Periods" which is what makes them "Inter-Glacial Periods" so in one respect this is entirely straw man territory. If the bold assertion is that glaciers and ice sheets shrink as they do today throughout an inter-glacial, that is false as sea levels of past millennia demonstrate.

"Sea levels are normally 4 meters to 14 meters higher than they are now during Inter-Glacial Periods." This is not supported by the evidence that
suggests only two or three of the eight had higher sea levels. (The graphic is from here but originates from this web engine.)
800,000 years sea level

"Global temperatures in the other 8 previous Inter-Glacial Periods were at least 7°F warmer than present." Again not supported by the evidence. A google search provides many graphical representations of 800,000y temperatures and globally the present interglacial has been warmer than all but three of them (although AGW may be on course to change that ranking).
800,000 year temperature

"The West always undergoes a drought during Inter-Glacial Periods." This is a more specialist assertion. That there has been "a drought" in "the West" through the Holocene is potentially correct. It isn't a place with massive rainfall. But more accurately there are periods of drought and periods when the rain is heavier. What we see to make sense of that is a bit of a Hockey Stick situation with drought conditions becoming more wide-spread. The graphic comes from here an account which does address the question "Will anthropogenic climate change cause the West to get drier or wetter?"
West drought since 800AD

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 ? )

Peter Brannen's Paleo Proxy Twitter Thread

DK_ID at 09:49 AM on 9 March, 2021

@2, you are correct but I didn't think the changes over the last 2 my had much impact on the East Antarctic ice sheet and ocean sediments should be around for over 100 my.

However, there are problems with the impact theory. There are deposits that seem to indicate a bolide impact but studies of paleo-indian population density don't really support the theory. Also, you may know more than me, but I think the 1st evidence found for the YD was from Greenland ice cores. Greenland has, likely, been affected by past interglacials.

Peter Brannen's Paleo Proxy Twitter Thread

DK_ID at 05:52 AM on 7 March, 2021

I love paleo and am truly enjoying Peter Brannen's Atlantic article. Thanks for directing me to that. I'm not done (slow reader) but do have one comment. His reason for the Younger Dryas, the generally accepted reason, is not the only explanation. One problem with Lake Agassiz spilling into the North Atlantic and shutting down the AMOC, thereby causing the Younger Dryas, is that other interglacials should have followed a similar pattern, but the brief return to glacial conditions is absent from the earlier records.

Another possibility is that a large comet struck North America at the beginning of the Younger Dryas. If so, it not only initiated the return of ice but ended the Clovis culture. Maybe such a strike might have disturbed the lake, leading to its premature exit? I forget where I 1st read about the impact theory but is was after the 91 references in the Wikipedia article.

2021 SkS Weekly Climate Change & Global Warming Digest #4

Philippe Chantreau at 05:03 AM on 29 January, 2021

Suggestion for upcoming digest: Seasonal origin of the thermal maxima at the Holocene and the last interglacial

Unfortunately behind paywall, but seems to elucidate a discrepancy between data and modeling in paleoclimate.

More CO2 in the atmosphere hurts key plants and crops more than it helps

Nick Palmer at 01:00 AM on 27 December, 2020

Worth considering is that when the denialist lobby drag up periods of Earth's pre-history when things were warmer than today and life was far more abundant pole to pole that was because Earth had no cold ice caps and maybe that explains why the AVERAGE global temperature was higher - but that doesn't, mean that equatorial and temerate zone temps were higher too. Any paleo climatologists around who could confirm this?

Human Fingerprints on Climate Change Rule Out Natural Cycles

knox kp at 09:26 AM on 19 November, 2020

Towards the end of the '90's, the idea that maybe scientists were unawares of what constituted the planet's natural cycles over Earth's long history occurred to me, so I went looking, and quickly found something that answered my questions/doubts: paleoclimatology.

So this latest nonsense was in the ether, as it were, more than twenty years ago - so tired of going backwards, discussing the same things agaian and again - don't see the advantage to any but the already wealthy.

CO2 effect is saturated

Eclectic at 07:50 AM on 28 October, 2020

Aoeu @587 , permit me to add my 2 cents as well.

The WUWT article is a "nothingburger" - and worse.

The WUWT editor has given a completely fallacious headline. (Typical for WUWT) The article is based on a paper - unpublished - by two scientists, one of whom is the eminent Dr Happer. It is claimed that Happer's paper has been knocked back by three major journals . . . and reading the paper soon shows why a scientific journal would not bother to publish this paper.

You will see from the above comments by MA Rodger and Tom Dayton, that the Happer paper comes out with a CO2-doubling Climate Sensitivity of 2.2 degreesC . . . a finding which is wildly misrepresented by the WUWT editor. This 2.2C sensitivity is slightly below the 3.0 figure which is a fairer "average" of sensitivity assessments (based on paleo and modern empirical evidence). So really nothing new there.

The paper has two weaknesses. It makes no allowance for cloud effects (the paper is a "clear sky" model). And as a minor point, it uses constant relative humidity in its modeling. Apart from that, I have no particular criticism to make . . . other than the humorous one where a typographical error shows "temperature region" where "temperate region" was meant ;-)

Clearly the Happer paper is not worth publishing.

Sadly, the blog WUWT is trumpeting this paper to the skies (excuse pun). WattsUpWithThat and its denialist clientele are always desperate to make much of anything at all which comes even within a million miles of casting some doubt on mainstream climate science.

Aoeu, have a look at the WUWT comments column below the article. There are all sorts of frothing-at-the-mouth comments . . . that this new paper overthrows all previous climate science / disproves the Greenhouse effect / exposes the incompetence & corrupt criminality of all the thousands of climate scientists worldwide. Etcetera. All the usual WattsUpWithThat nonsense and crackpot lunacy. But among all the madness, you will find a few pearls of wisdom by the genuine scientist Nick Stokes (who is thoroughly hated by the usual WUWT clientele).

We can expect the Happer paper will be a Nine Day Wonder in many parts of the bloggy Deniosphere . . . until they abandon it for the Next New Thing (by Lord Christopher Monckton or whoever). It is all very entertaining . . . but it ain't science.

Climate's changed before

Eclectic at 10:44 AM on 25 October, 2020

Hal Kantrud , I would like to add a few disparate points which may be of interest to you. (And you may already have come across some of them.) As always, I shall be grateful if MA Rodger (who is extremely well-informed on climate matters) sees fit to make any corrective comment!

1. The term "BP" / bp stands for Before Present, but does not mean "up until right now this year of [2020]". BP is a convention used by the paleo scientists to standardize the reference to past ages - whether centuries, millennia or mega-years [ma]. BP at point zero is taken as year 1950.AD

Some "contrarians" have not been aware of this convention (for instance the slightly-contrarian scientist Loehle has had to go back and correct some of his work, because he was initially unaware of the paleo convention).

Hal, this paleo convention is enormously important, since there has been a huge rise in global surface temperature since 1950. Even today, some Denialist blogsites are publishing graphs which misrepresent reality, and are showing a graph's final temperature as 2000.AD or 2010.AD . . . when the original graph only went up to 1950.AD . . . and worse, the denialists have sometimes doctored or airbrushed-out the most modern temperatures. Sometimes this deliberate deception is outright concealed - and sometimes the deception is camouflaged under the term "Adapted from [a certain scientific paper]" .

Another small point is that some of the ice-core temperatures are recorded up until around 1855.AD , since later/shallower levels of ice are unrepresentative of their ambient conditions.

[You will have noticed how almost all science-deniers are still falsely (and vehemently) asserting that both the Holocene Maximum and the MWP were hotter than 2000.AD and current years.]

2. The Holocene Optimum [sometimes called Holocene Maximum] was roughly 8000 years ago, but as MA Rodger rightly points out, the Maximum was more of a plateau of roughly 5 millennia. Over the succeeding 4 or 5 thousand years, the temperature has dropped roughly 0.7 degreesC as part of the background cooling which would eventually lead into the next glaciation. But AGW has intervened - with global temperature rising like a rocket in the past 100-200 years (dare I say like the end of a Hockey Stick?) Hockey Stick is yet another term which causes Denialists to choke on their cornflakes.

As a consequence of the natural cooling down from the Holocene Maximum, the global sea level has reduced by about 1 or 2 meters . . . and that fall should have continued onwards as we slide into the next glaciation. Except for the modern AGW-caused rise in sea level, a rise which is slow but accelerating.

3. Each glaciation cycle of the past 800,000 has been subtly different, owing to differences in the variations of the Milankovitch cyclings. That makes it difficult to predict when the next glaciation would have occurred in the absence of human influence. One figure I recall seeing, is the next chilly glaciation being due in roughly 16,000 years. So we humans have plenty of time to fine-tune our climatic effects before any threat of severe glaciation! (Some denialists maintain that the "New Ice Age" was due in a few centuries from now . . . and our anthropogenic CO2 has fortuitously been raised only in the nick of time... )

4. I won't comment on your point of interest about the New World grasslands. The changes there would be quite minor in the overall picture.

What does the global shift in diets mean for climate change?

nigelj at 17:40 PM on 13 October, 2020

Humans are omnivores after millenia of evolution, eating a wide variety of food groups in rough balance, so extreme diets go against our nature whether vegetarian, or atkins and paleo high meat diets, so I would need very good science based proof they are good for us. They all look like quackery to me.

I see the merit it lower red meat consumption for climate, efficiency, cost and health reasons, but some land looks like it only really suits cattle grazing so eliminating all red meat seems unrealistic. I think a mixed diet of some red meat, some fish, some chicken and also beans for protein and grains and fruits makes sense and its what I eat and enjoy. Humans are omnivores, so don't reinvent that wheel.

2020 SkS Weekly Climate Change & Global Warming News Roundup #35

nigelj at 13:31 PM on 7 September, 2020

Gseattle @22, the link you post from principiascientific.com is part of a very politicised website. The link you post is also not convincing. Its full of basic misunderstandings so the maths ends up proving nothing.

I will try to explain this in my own words and keep it simplified. What actually happens is natural sources of CO2 largely exist in a balanced equilibrium with nature where emissions are absorbed by natural sinks, on decade to decade time framnes. For example the photosynthesis cycle. The paleo record shows all this, so its settled science. So CO2 stays largely constant in the atmosphere on decadal time scales.

Now sometimes things get out of balance if there is a sudden source of emissions and CO2 builds up in the atmosphere for example a truly huge volcanic eruption (these are uncommon) , or as part of the ice age cycle, so atmospheric CO2 increases on decades to centuries time scales. Again we know this from the paleo record. Eventually this reverses very long term as CO2 is absorbed by rock weathering processes, so you get balance again and no run away increase.

Over the last 100 years or so natural sources of CO2 have been in balanced equilibrium. There has been no build up in the atmosphere from natural sources. The build up in CO2 cannot be explained by natural causes. Volcanic and geothermal activity has been stable. The slowing AMOC is not causing the oceans to release CO2. We know this because the oceans are acidifying, so absorbing CO2 - the excess CO2 from burning fossil fuels being the obvious explanation. The reversal of the earths magnetic field started well before the 100 year increase in CO2 so cannot be responsible. There is no plausible causative mechanism anyway.

You dont even need any huge amount of science to figure these things out. Its just having a reasonable knowledge of the issues and some logical deduction. This is how I approach it.

The increase in CO2 in the atmosphere over the last 100 or so years is not from "natural causes". Multiple lines of evidenc point to all this. You have been given explanations by MAR and references to read on this websites myths column by eclectic, based on peer reviewed published reasearch, and you ignore these, and do not explain which elements you dispute, and instead post something by "eberry.com" which is not published research and author not identified. It suggests you just dont want to accept the possibility humans are causing the increase in CO2.

I think you need to ask yourself why you are doing all this. There is of course nothing wrong with healthy scepticism of scientific theories, but its silly to be sceptical when all the evidence points one way so convincingly, towards foosil fuels ebing the source of the CO2, and towards AGW, so the fact you continue to be sceptical suggests you either 1) simply do not understand or 2) are determined not to understand, perhaps being instead driven by some undeclared narrative whether political or conspiratorial or whatever.

2020 SkS Weekly Climate Change & Global Warming News Roundup #35

Eclectic at 10:55 AM on 7 September, 2020

Gseattle , best if you exert yourself to making genuine points of argument, rather than use empty rhetoric (which is something that Moderators tend to zap). [ And yes, I do enjoy posting on this thread! ]

It would be helpful to readers (and possibly to yourself) if you clarified the underlying problem you have with Greta Thunberg.

Looking at the bigger picture : it sounds dramatic to say "200 species extinct every day". How accurate is that? ~ quite probably it is accurate enough for practical purposes (of guiding our actions).

Why probably? : well, there are many millions of species . . . and millions more of species which are not yet discovered/identified. The ecological balance has been tilted against these species, and so it is hardly surprising that you get a dramatic answer if you divide a very large Numerator by thousands of days.

We already know even prior to the current major warming . . . that the expanding human population has tilted the balance strongly ~ thanks to de-forestation, extensive agriculture, over-grazing, pesticide usage, etcetera etcetera. And we know from the paleo evidence, that the comparable rapid warming episodes of the past have caused massive extinctions.

IOW : at present, the plants & animals are being hit by a "Double Whammy". So you should not be surprised at the level of extinctions per day. And there seems little point in you arguing whether the "200 per day" might only be "100 per day".

The major concern is ~ What should be be done about these changes in the real physical world? Should we sadly shake our heads, and sit on our hands? Should we engage in a game of Trivial Pursuit, and spend our time discoursing about "200" or "50" or "100" ? Or should we look at the bigger picture, and avoid distractions, and take intelligent action?

What is your choice, Gseattle ?

Spreading rock dust on fields could remove vast amounts of CO2 from air

Eclectic at 18:25 PM on 14 August, 2020

Daveburton @17 , the Moderators at SkS are typically rather sparing in "striking out or striking through" plain nonsense (such as your CO2 comment in #10 ).

Alas, the Moderators at WUWT are even more sparing : have a look at the comments columns at WUWT ~ where 80 or 90% of comments would get the chop, if moderation were applied by the criterion of common sense.

Dave, you have misunderstood the Moderator's response at #10 . He was not asking for a Gish Gallop. Implicit was the request (in accordance with the Modus Operandi here at SkS ) that you select the individual topics where you think the mainstream science is faulty or tied to poorly-pragmatic conclusions. (And contrary to your "models" comment, the pragmatic conclusions are based on ordinary physics & common sense ~ reinforced by the paleo evidence. None of this "61 floors and okay so far" business. The "models" projections/estimations may or may not give further insights into the climate processes & possibilities . . . but the models are definitely not the foundation of climate science. )

So, please select one individual topic which you believe is "wronged" ~ and discuss that one in the most appropriate thread here at SkS. And when that topic has been suitably discussed/resolved . . . then select your No. 2 choice, and find the right thread for that. And so on.

Good luck. (But it seems you are unaware of the sensitivity of maize yield, to heat waves.) And you may be in danger of becoming a skeptic (and thus with little chance of "life" on the WUWT blogsite.)

Spreading rock dust on fields could remove vast amounts of CO2 from air

Eclectic at 15:39 PM on 14 August, 2020

Very entertaining, Daveburton @14. It's exactly why I enjoy viewing the Motivated Reasoning gymnastics by the regulars at WUWT.

Especially your bit where: "we've raised atmospheric CO2 levels for 61 consecutive years". Reminds me of the old joke about the optimist who fell off the top of the Empire State Building . . . "61 floors and okay so far". (I am sure you've heard something like it.)

Such cherry-picking. (I note cherries are always in season at WUWT.) Though you haven't yet played your ultimate argument ~ the Conspiracy of all the world's scientists, and their faked data. And all that faked paleo data, too.

But you will probably get around to your penultimate argument :- "Forest . . . what forest?"

Still, Dave, this is all a tad off-topic for this particular thread. Find one of the old threads for this old stuff. (And why are you coming out with such old stuff . . . right now? Is it a sign that a seed of genuine skeptical doubt is starting to germinate in your brain? Beware !! )

2020 SkS Weekly Climate Change & Global Warming Digest #30

wayne at 02:11 AM on 30 July, 2020

Sailrick, I kind of agree with you. It's more a ruling out of low end then high end states. Personally I will place more importance on the paleontological evidence. If we're 1C+/- now

+ 0.2C for the pre-preindustrial warming

+ 0.5C for aerosols

plus you have a 30year/66% lag meaning the temperatures were experiencing now are more indicative of 350ppm than 420ppm. So I see your point on how a +40% increase in CO2 has in all probability commited us to +2C rise in 150yrs. This doesn't address what the end state will be in 1000yrs or more. Now instead of a 40% increase imagine an actual doubling its obvious that a 2C warming shouldn't even be in the equation

Climate sensitivity is low

Cedders at 01:29 AM on 24 July, 2020

The big news announced yesterday is the narrowing of equilibrium climate sensitivity (ECS) from a combination of paleoclimate and historical measurements and feedback modelling, a study which will feed into IPCC AR6. As I understand it, ECS is now very likely (90% likely) to be within 2.0‐5.7 °C, and likely (66% probability) to be 2.6‐3.9 °C, with a longer tail above 4.5 °C than below 2 °C. Anyone 'gambling' on low sensitivity would lose. Sherwood et al, "An assessment of Earth's climate sensitivity using multiple lines of evidence", Reviews of Geophysics, 2020. http://dx.doi.org/10.1029/2019RG000678

The following long review tells me more than I need to know about feedbacks of all kinds: Heinze et al, "Climate feedbacks in the Earth system and prospects for their evaluation", Earth System Dynamics, 2019. https://doi.org/10.3929/ethz-b-000354206
Although there may be 'black swan' events and earth-system feedbacks, the idea that climate scientists aren't including albedo or cloud changes in models is incorrect.

More recent info on feedbacks in the latest CMIP6 models is in Meehl et al, "Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models", Science Advances, 2020. https://doi.org/10.1126/sciadv.aba1981 and Zelinka et al, "Causes of Higher Climate Sensitivity in CMIP6 Models", Geophysical Research Letters, 2020. https://doi.org/10.1029/2019GL085782, the latter including a nice figure S7 showing the contribution of different feedbacks in different models.

Models are unreliable

MA Rodger at 05:18 AM on 8 July, 2020

ClimateDemon @1252,

Are you familiar with the United Nations Intergovernmental Panel on Climate Change? I ask because your comment @1252 only makes sense if you are not familiar with this organisation and its work. I would draw your attention to IPCC AR5 WG1 which reviews the science showing both that "there is global warming" and that "humans are causing it." I would draw your attention to Chapter 10 'Detection and Attribution of Climate Change:from Global to Regional' and, as you have show interest specifically in the role of CO2 in the global warming, also Chapter 5 'Information from Paleoclimate

Models are unreliable

ClimateDemon at 06:55 AM on 5 July, 2020

There may be some interesting points in this paleo evidence and the “bigger context” described by Eclectic, but it’s not really the issue I am trying to address. What I am trying to address are the current arguments for CO2 being the “control-knob” GHG (despite the fact that H2O vapor is the stronger GHG) which subsequently leads to the claim that humans are overheating the earth with their CO2 emissions, and that our very survival depends on government intervention. Now, in every reference I can find, including the Lacis et. al. 2010 paper and this website, the reason given for CO2 being the controlling GHG is that H2O vapor is condensable whereas CO2 is not. Furthermore, it is asserted without clear grounds that the H2O vapor concentration is given by the Clausius-Clapeyron equation at the current temperature, or IOW at 100% relative humidity. With this constraint on the H2O vapor concentration, it can then be only a feedback to temperature changes. CO2, however, has no such constraint and can actually cause temperature changes simply by adding more of it. This is the argument by which CO2 becomes the controlling GHG even though it is the weaker GHG. Note that without somehow constraining H2O vapor to being a feedback only to temperature change, then the entire basis of AGW collapses since H2O would then be the controlling as well as the stronger GHG. Humans may have some control over the amount of atmospheric CO2, but not H2O vapor since over 70% of the earth’s surface is covered with H2O liquid.

Therefore, we see that the AGW theory stands or falls on whether or not CO2 is the controlling GHG, and I believe I pointed out (in 1173) some serious problems with the arguments in favor of the CO2 “control knob”. If these problems are not adequately resolved, it would be a real “show-stopper” for the AGW theory.

Models are unreliable

Eclectic at 21:40 PM on 4 July, 2020

ClimateDemon @1213 , the bigger context is the paleo evidence ( you can start reading at (SkS) Climate Myths 12 and 13 , and expand out from there.

The modern empirical evidence ~ a temperature rise of 1 - 1.2 degreesC since industrialization 1850-ish, all with a 1.4x rise in air CO2 . . . and your own back-of-envelope logarithmic calc extrapolates that to around 2.0 - 2.4 as TCS and hence ECS around 30-40% higher again. IOW, an ECS of around (roughly) 2.5 -3.5 C. [Which is way higher than the deluded Lord Moncton "calculates".] And which also fits with the paleo estimates.

That all connects well with the "CO2 control knob" (remember to adjust for solar brightening/dimming over time). Find the right thread, if you wish to comment.

Models are unreliable

ClimateDemon at 19:34 PM on 4 July, 2020

Eclectic @1174

Please explain what you mean by the bigger context, and paleological evidence. Also, please explain how your CO2 "control knob" is supposed to work.

Models are unreliable

Eclectic at 17:04 PM on 4 July, 2020

Philippe C , I may have to back-pedal on my skepticism about your Questionable Lady hypothesis. There does indeed seem to be a Curry worship of almost Sub-Continental dimension. Perhaps the good Doctor has a Mrs Hyde facet to her personality?

Deplore_This , your truculence & tone-policing are a red flag. So much so, that your "search for a GCM course" seems merely a pretext for your postings.

Yet if you do have a genuine concern about the value of climate models, then please express those concerns in your own words. Without doing a "cut and paste" from the typically vague and non-substantive rhetoric which is the standard output of Dr Curry.

You seem not to be aware that the GCM's are not the basis of climate science nor are they the basis of expectations of continued global warming & the consequential major problems. The basic physics / paleo climate evidence / and the past 150 years of empirical evidence of climate response to rising atmospheric CO2 . . . all combine to give adequate grounds for policymakers to take urgent action to reduce CO2 emissions.

Climate models can sometimes be used as a test bed for certain sub-components of climate or energy fluxes. And they can (famously) produce a large range of interesting projections. But their pragmatic usefulness for projections, is low for the present & near future.

And that should be very obvious to you, when you take note of the wide range of Equilibrium Climate Sensitivity which is generated by the typical models. In other words, Deplore_This , you will largely be wasting your time if you pursue "a course in GCM's" . You really really do need to study the basic science of climate.

Models are unreliable

Deplore_This at 01:25 AM on 4 July, 2020

@scaddenp

As I stated in my first post 1162 I am an anthropogenic climate change skeptic because I’ve read criticism of the validity of the climate temperature models referenced by the IPCC like those posted in 1193 and 1194. The corrupt media and the bureaucrats at the EPA say it’s settled science but I see no record of balanced climate research or any open debate. It appears that scientists who raise doubts of the validity are shunned and unfunded.

So my dilemma is how do I know what and who to believe. It is my nature not to blindly believe anything, especially what the government tells me. I thought a solution would be to take a university course in climate modelling so that I could hands on use and understand the development of GCMs and form my own opinion. If this was the 16th century and I’d probably get a telescope to test Galileo’s claim of heliocentrism. I am surprised to find that there aren’t such courses which leads to an even more startling revelation that the majority of the “97% of climate experts agree humans are causing global warming” have never been taught or used a GCM themselves and base their opinion on the opinion of others. To me that looks more like group think than science. And they call us climate skeptics “flat earthers”.

So my dilemma remains and I’m not sure what to do next. I may contact Penn State and see if course material is available from their last course on GCM. I’m not going down the paleological path because there are other issues there and because the IPCC’s opinion that is used for public policy is based on GCM predictions. I remain open to any suggestions. Thank you again for your help.

Models are unreliable

Deplore_This at 08:33 AM on 3 July, 2020

@scaddenp 1177

Thank you for your response. I don’t know what an AOGCM computer model looks like under the hood which is why I am looking for a university course on them. I have a minor in math, I took differential equations, I’ve taken Physics in Engineering school, I’ve not only written computer code but in my career I’ve project managed the creation of multi-million dollar IT systems. I wasn’t planning on writing a half million lines of code but I haven’t seen anything yet that would make me believe I would be in over my head working with an AOGCM model. But I haven’t been successful finding a way to actually work with one.

I am somewhat confused by your comment. I would think there would be a plethora of courses on climate modeling otherwise how would all of the climate scientists learn how to construct and evaluate them? We have legions of climate researchers at the EPA, who taught them?

I understand the paleoclimate approach but I am specifically interested in understanding the more sophisticated AOGCMs, specifically their fidelity on climate sensitivity. I’ve gone through the WG1 report and read the results and conclusions. But there are scientists who disagree with their conclusions. To understand the competing arguments I’m trying to educate myself on the models they are using and how they are used. I thought that taking a university course on the subject would be a good approach but not finding one I am stuck. How do the climate researchers at the EPA get the knowledge of which expert and model to believe? What course would they take?

Thank you again for your help.

Models are unreliable

scaddenp at 07:44 AM on 3 July, 2020

Climate models are around 0.5 million line of code created by discipline experts for each of the climate processes. Starting from scratch to write your own is somewhat ambitious. Note that they are not statistically based so I am skeptical that a background in stats or operations research would help you much. The background requirement is numerical solution to systems of partial differential equations. No shortage of courses of these.

I cannot comment on US university or course, but going into serious atmospheric sciences here would be based on undergraduate degree in physics and maths. The numerical solution of systems of partial differential equation is specialist area of mathematics - numerial analysis. Our institute (geology/geophysics) typically has mathematicians, programmers and subject specialists working together on problems of this kind of class.

I still think predicting the base level of future isnt that hard. If surface irradiation increases, then surface gets warmer. The complicated bit is by how much will feedbacks magnify that effect. (Equilibrium Climate Sensitivity) And yes, predictions of future are based are done by AOGCMs. However, there are also paleoclimate constraints on climate sensitivity. Too crude compared to models but good enough to cause serious concern. Again, the WG1 report is good place to find the papers on emperical constraints on climate sensitivitiy.

Models are unreliable

Eclectic at 22:35 PM on 2 July, 2020

ClimateDemon @1173 ,

Your "CO2 control knob" ideas fall flat, because you have made the critical mistake of looking at climate models only.

If you look at the bigger context, and examine the paleological evidence, then it becomes very evident CO2 has exerted a major "control knob" effect on planetary climate. That is also reinforced by the empirical evidence of modern historical data.

It's only a few degrees

MA Rodger at 21:00 PM on 30 June, 2020

Jasper @3, Yet another take.

You write "I get that a few degrees make a huge difference. I don't fully understand why a few degrees matter so much." Although a huge difference is suggestive that it does matter, I read your meaning that you are after an authoritiative take on the effects of "a few degrees" and something with a bit of meat on it.

Warming the globe by "a few degrees" will make a big difference to the climate system which has been previously reasonably fixed for millenia and so will bring unprecedented change for human civilisation. But providing an authoritative account of what that change will amount to isn't so easy.

Will those "few degrees" be enough to stop the AMOC and plunge Europe into a mini-ice age, enough to broaden the Hadley Cells and turn the central US lands and the Mediterranean lands into deserts, to green the Sahara and turn the Amazon into a treeless savannah? The answers are not straightforward. There is no long list if definitive outcomes set out in the headlines of the IPCC AR5 Synthesis Report. The word "risk" features too often when IPCC describes such outcomes.

IPCC AR5 SYN SPM Fig8

But there are a couple of definitive temperature-related outcomes from AGW.

One is that Greenland will melt out somewhere between +1ºC and +2ºC threatening serious sea level rise. (The IPCC AR5 puts the upper bound at +4°C which is rather a fudge. Antarctica's ice caps are similarly a threat but how quickly they will react to global temperature rise is not well enough understood to be so predictable.) Another is the habitability of the tropics for humanity and perhaps a third is ocean acidification which would be unprecedented in tens of million of years.

If Greenland were to melt down (a process that once started will not stop as the top of the Greenland ice sheet today sits happily frozen high up in the cold upper atmosphere), the oceans would rise by over seven metres. This compares with the last six thousand years (which spans the period of human civilisation) when changes in sea level could be measures in centimetres. A seven metre rise would be a big problem as so much of our populations today live close to sea coasts. (About a third of humanity inhabit land less than 100 metres above sea level while the loss of both Greenland and Antarctica would raise sea levens 75 metres.) The melt-down of Greenland would take a few centuries to make its mark but the process certainly becomes unstoppable if global warming remains two degrees centigrade above pre-industrial.

The "few degrees" global temperature rise that accompanied the warming from the last glacial maximum 20,000 years ago and the dramatic impact on climate has been mentioned up-thread. The change in climate resulting from another similar-sized rise in global temperature would be just as dramatic for humanity. If global temperatures rose by six degrees celsius above pre-industrial, it could perhaps be described as a "Steam Age" as the increase in wet bulb temperatures would make the tropics a death trap for humans outside air conditioning. And such a six-degree temperature increase by 2100 is within the projection of the Business-As-Usual scenario of the IPCC.

The ocean acidification would rival that of the PETM 55 million years ago but would happen in decades rather than tens-of-millenia.

There is a big pile of reason not to let AGW run beyond +1.5°C. The implications for humanity and for much of the biosphere will be catastrophic if we let AGW run. It's a bit like jumping off a cliff. Predicting the height it would require for the fall to split your skull open is not straightforward but that is no reason to consider jumping. Besides, when you fall it's the intracranial hypertension that usually kills.

PETM climate warming 56 million years ago strongly tied to igneous activity

ubrew12 at 08:55 AM on 23 May, 2020

Part 3: "both the Gutjahr et al and Jones et al research suggests that any amplifying feedback from an extra carbon reservoir (like clathrates or permafrost) was small if it existed at all in the PETM world" The reason for this seems to have been answered in Part 1: "[to have caused the PETM]...a large reservoir of clathrates...[needed] to be there... We know they exist in today’s seabed but the Paleocene ocean was much warmer than today’s, so the reservoir was probably as good as empty [... and the lack of permafrost as a PETM trigger is similarly explained]."

So we may not be out of the woods, on feedbacks, just yet.

Skeptical Science New Research for Week #9, 2020

nigelj at 06:30 AM on 7 March, 2020

MAR, "More directly addressing your question, the ice cores do show a small increase in CO2 levels over the last 8,000 years..."

The Marcott study here shows global temperatures falling over about the last 3500 years until about 1900. So perhaps the milankovitch cycle cancelled out the slow low level rise of CO2 concentrations over the same period?

CO2 lags temperature

Philippe Chantreau at 03:44 AM on 3 February, 2020

I believe that I had read Map's initial comment correctly and that he is indeed referring to what some call the Mid-Pleistocene transition. This is an area of active research and, although his posts are poorly formulated, I do not see that map deserves scorn for enquiring about it.

The recent regime of 100,000 years interglacial was preceded in the paleo record by a longer period where the 41,000 years cycle dominated. Wikipedia has a good explanation and plenty of links to scientific literature, including some recent ones.

Citing the wiki page:

"There is strong evidence that the Milankovitch cycles affect the occurrence of glacial and interglacial periods within an ice age. The present ice age is the most studied and best understood, particularly the last 400,000 years, since this is the period covered by ice cores that record atmospheric composition and proxies for temperature and ice volume. Within this period, the match of glacial/interglacial frequencies to the Milanković orbital forcing periods is so close that orbital forcing is generally accepted (emphasis mine). The combined effects of the changing distance to the Sun, the precession of the Earth's axis, and the changing tilt of the Earth's axis redistribute the sunlight received by the Earth. Of particular importance are changes in the tilt of the Earth's axis, which affect the intensity of seasons. For example, the amount of solar influx in July at 65 degrees north latitude varies by as much as 22% (from 450 W/m² to 550 W/m²). It is widely believed that ice sheets advance when summers become too cool to melt all of the accumulated snowfall from the previous winter. Some believe that the strength of the orbital forcing is too small to trigger glaciations, but feedback mechanisms like CO2 may explain this mismatch."

Further down: "During the period 3.0–0.8 million years ago, the dominant pattern of glaciation corresponded to the 41,000-year period of changes in Earth's obliquity (tilt of the axis). The reasons for dominance of one frequency versus another are poorly understood and an active area of current research, but the answer probably relates to some form of resonance in the Earth's climate system. Recent work suggests that the 100K year cycle dominates due to increased southern-pole sea-ice increasing total solar reflectivity."

Worth noting:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL071307

There are plenty of other interesting references in the Wiki.

Map,

To have a productive exchange here, you can not be vague with statements like "I have read somewhere" and such. These are used all the times by people who argue in bad faith and trigger the corresponding response from other posters, for which you can not blame those who respond. Scientific references are a must. Specific inquiries and precise questions are helpful.

It should be noted that the regime in the paleo record has now been completely replaced and that we are in entirely new conditions because of the massive injection of CO2 in the atmosphere from the past 100 years.

CO2 lags temperature

michael sweet at 20:27 PM on 2 February, 2020

MARodger,

Thank you for the reference to the 2006 report in NASA's Earth Observatory, they do say 15F in 10 years. When I found their referenced source of the GISP2 temperature and accumulation data (file did not open on this computer, sorry for no link), the data is all sectioned off in 50-80 year sections so a 10 year claim is not supported. In addition, 15F would be about 8C and there is no change anywhere near that magnitude (in 50 years not 10) in the record. It seems to me that the NASA report has a typo in it.

To address Map's question, this is data for a single location on Greenland and not global data. The temperature change in Greenland was over 20C since the last ice age while Earth average was 4C according to the data in the OP. In addition. there is much more noise in data from a single location than from an average for the entire Earth. Conflating Greenland data for the Earth's average is simply incorrect.

You ask several questions in your last post. It is difficult to respond to several questions separated only by a question mark. Please ask one at a time. Start with the one that is most important to you.

1934 - hottest year on record

MA Rodger at 18:55 PM on 2 February, 2020

For the record, the "one-third to one-half of the warming—about 15 degrees Fahrenheit—occurred in about 10 years." quote mentioned @111/112 originated at NASA's Earth Observatory back in 2006.

Ocean acidification isn't serious

MA Rodger at 21:09 PM on 21 January, 2020

This has all got a bit shouty in a couple of days. Perhaps to return to the initial question @84. Markoh asks:-

"The bit I don't get is that all the limestone deposits in the world which is calcium carbonate were produced when the atmospheric CO2 was many times higher than today. So how did all the shellfish create so much shells that it formed huge limestone deposits with the very high atmospheric CO2 back then??"

I should point out that there is an SkS OP that directly addresses this question (Why were the ancient oceans favorable to marine life when atmospheric carbon dioxide was higher than today?) but perhaps a more succinct answer would be useful here.

Although limestones apparently predate shellfish, shellfish (or molluscs with mineral shells) date back to the Cambrian period when ocean pH was lower than today (perhaps 7.9pH or as low as the 7.3pH modelled by Ridgwell 2005). It is only in the last 30My that ocean pH was high as today (& atmospheric CO2 as low as today). With rising atmospheric CO2, the ocean pH is now falling (today it has fallen from 8.2pH to 8.1pH) and making the chemistry of shellfish more difficult. Those organisms using high--magnesium chemistry (as opposed to argon- or low magnesium-chemistry) will be especially vulnerable as will organisms who do not calsify their shells 'internally', but all will suffer. The last example of CO2 driving ocean acidification (the PETM 55My ago) saw limestones entirely absent from geological formations.

However, it is not the ocean pH that is directly the problem. It is the low concentration of calcium ions that makes shell-formation difficult and such concentrations being pushed low by dropping in pH, not by low pH. Thus over most of the last 500 million years, ocean pH was much lower than today and during these times shellfish thrived.

Ocean acidification isn't serious

scaddenp at 10:45 AM on 21 January, 2020

It is not in dispute that limestone has been laid down when CO2 concentrations are much higher than today (though buffering means that pH was still around 7.5 or higher). See references I supplied further up. It means that organisms have to expend more energy to extrude shell which over long time frames they can adapt to.

However, the issue today is very rapid change in CO2 which results in acidification proceeding faster than organism can adapt and far, far faster than buffering by weathering can ameliorate pH. The paleo record shows this has been a problem for organisms in the past during such rapid excursions, and worse still, CO2 levels may be climbing far faster than in any known previous acidification events. Look for papers on PETM.

I had an intense conversation at work today.

nigelj at 06:38 AM on 17 January, 2020

barryn56 @42, just my 2 cents worth. Climate models have proven to be quite good at predicting the future, including temperature trends. Go to realclimate.org and theres an article on their home page about half way down.

Yes there are uncertainties about the more distant future due to uncertainties about clouds etc, but the weight of evidence from modelling, temperatures over the last couple of years, and the paleo history suggests we are in for a lot of warming. The thing is a lot of evidence points in the same direction, and it would be foolish to dismiss that.

You mentioned something that appears to have been deleted due to sloganeering rules. You said something like cloudy nights are very warm because of water droplets and ice in the clouds, implying that water vapour and CO2 are very weak greenhouse gases. Please note that humid nights with no clouds are also very warm. I'm not a climate expert, and some healthy scepticism is good, but dont jump to conclusions before doing your homework very carefully.

Doubling down: Researchers investigate compound climate risks

nigelj at 15:50 PM on 10 January, 2020

Ignorant Guy @28, J Hansen talking about 10X worse wind speeds may have been referring to 'superstorms' in earths past. Theres some paleo evidence for these huge storms. Research paper here.

Doubling down: Researchers investigate compound climate risks

Ignorant Guy at 17:35 PM on 9 January, 2020

There was some controversy about future storms going to be "10X worse" (mentioned first dkeierleber, #9) and Hank at #10 said that claims of storms 10X worse is unrealistic and unhelpful and then OPOF, #11, said "I [...] agree that wind forces 10X worse are a long way off". But "worse" is not a SI-unit or in any way rigorously formally defined. I don't think what was meant from the beginning was 10X windspeeds. I tried to find the paper by Hansen 2015 to look for mentioning of 10X worse storms but didn't really find it. I did find this:
"increment [...] as much as 10-20%. Such a percentage increase of wind speed in a storm translates into an increase of storm power dissipation by a factor ~1.4-2, because wind power dissipation is proportional to the cube of wind speed " (mentioned in "Ice Melt, Sea Level Rise and Superstorms: Evidence from Paleoclimate Data, Climate Modeling, and Modern Observations that 2°C Global Warming is Highly Dangerous", Hansen et al, 2015).
So wind power increases much faster than linear with wind speed. I can imagine then that damages also increases faster than linear with wind power. So it is not completely unreasonable to to foresee future storms to be 10X as destructive, "destruction" measured as cost of damages.

The never-ending RCP8.5 debate

Evan at 13:53 PM on 31 December, 2019

Nigelj@23

I don't want to nitpick too much, but I'm sure you're aware that during the last deglaciation that an increase of 1 ppm/100 years was enough to drive sea level up 5m/century for about 3-4 centuries (i.e., meltwater pulse 1A). We are now driving up CO2 at 1 ppm/5 months. It seems to me that 5m/century is very much in line with the paleo record given how hard we're pushing the climate.

The never-ending RCP8.5 debate

nigelj at 12:26 PM on 31 December, 2019

michael sweet @21

"You appear to be arguing that your opinion is more valuable on any topic than experts in the topic that you deem "dead wrong". On this board you need to post links to support your wild claims."

I did supply a reference to the wikipedia article on Hadley Cells, which in turn quoted:

Xiao-Wei Quan; Henry F. Diaz; Martin P. Hoerling (2004). "Changes in the Tropical Hadley Cell since 1950".

Dian J. Seidel; Qian Fu; William J. Randel; Thomas J. Reichler (2007). "Widening of the tropical belt in a changing climate". Nature Geoscience.

I try to provide as many references as I can in the time I have, and I think I do quite well on the whole, and I wont be doing more.

"For example sea level rise. So far you have provided no support for your claims that 2 meters of sea level rise this century is "worst case" or will take "decades to centuries". Evan has provided a link that shows actual scientists think 15 feet is possible (although not the most probable event). "

I admit I didn't provide a reference for two metres. Yes you are right there are a few scientists predicting far more than two metres sea level rise per century. I forgot that. However its somewhat beside the point I was making, and the thinking of the wider communiry seems to be converging on 2-3 metres per century as a plausible worst case scenario, and that was in my mind, for example here:

phys.org/news/2019-05-metre-sea-plausible.html

Its absurd to suggest we could ramp up from current rates of sea level rise to 2 metres in the space of a couple of years, even Hansen didn't claim that. It misses the point anyway. My point was that there will at least be some time to adapt regarding finding more farm land. It will be harder to adapt in terms of physical infrastructure

Yes the IPCC worst case of 1 metre sea level rise looks far too conservative, a "keep everyone happy" sort of estimate and very frustrating. I've thought for ages that 2 metres / century is a very distinct possibility and needs to be in fornt of the public. I think I'm entitled to my opinion. There is good evidence in the paleo climate record for 2 metres per century at around 2 degrees of warming so nobody has to model anything, its a matter of historic record. But when people with a science degree start waving thier arms and saying 5 metres is possible by the end of this century, and that half the world could become a desert I wonder if thats plausible and helpful.

"Fast forward to 2016 and 18 coauthors backed a 5 meter top projection "
You are just doing the same thing again. Emphasising the extreme estimate from a small group of scientists, while criticising denialists who do the same. Nothing has happened in the real world to date to suggest 5 metres this century is possible. The very recent trends in the Antarctic and Greenland suggest 2 metres is possible from what I have read.

"This is a perfect example of what William Reese was arguing against. I do not think 6 billion people will die by 2100, but there are legitimate scientists who do support that claim. They are left out of the discussion. How can we come to proper conclusions of what path we should choose if we leave out the worst projections because we do not like them?"

They have not been left out of the discussion, because we are discussing them right now! Not that my opinion counts for much.

"You say "[William Reese's] views do not stand the test" but you provide only your opinion to test his against. You must provide data to support your wild claims."

I've provided some data that Reeses claims on vast areas of deserts are nonsensical, as mentioned above. That was my main point and appeared to be his main point. I concede I provided no reference when I mentioned sea level rise (:

"If 600 million people are displaced by sea level alone, along with destruction of prime, irreplaceable farmland, it is not much of a strech to see billions threatened by all of AGW's effects."

Arm waving and speculation. I agree billions would be threatened, but being threatened is not the same as being killed. Some precision is importrant, is it not?

I'm applying the mission statement of this website. "Scepticalscience". Are you?

I was born in 1958 as well.

Skeptical Science New Research for Week #48, 2019

John Hartz at 08:46 AM on 7 December, 2019

Doug @13: Here's the "About" statement posted on the website of MIT's Center for Global Change Science (CGCS). Note the final paragraph in particular:

The Center for Global Change Science (CGCS) at MIT was founded in January 1990 to address fundamental questions about the global environment with a multidisciplinary approach. In July 2006 the CGCS became an independent Center in the School of Science. The Center’s goal is to improve the ability to accurately predict changes in the global environment.
CGCS seeks to better understand the natural mechanisms in the ocean, atmosphere and land systems that together control the Earth’s climate, and to apply improved knowledge to problems of predicting global environmental change. The Center utilizes theory, observations, and numerical models to investigate environmental phenomena, the linkages among them, and their potential feedbacks in a changing climate.
The Center builds on existing programs of research and education in the Schools of Science and Engineering at MIT. The interdisciplinary organization fosters studies on topics as varied as, for example, oceanography, meteorology, hydrology, atmospheric chemistry, ecology, biogeochemical cycling, paleoclimatology, applied math, data assimilation, computer science, and satellite remote sensing.
CGCS sustains a program of discovery science with research on the natural processes in the global environment, concentrating on the circulations, cycles and interactions of water, air, energy, and nutrients in the Earth system.
Parallel CGCS activities incorporate the insight gained into climate prediction models, and climate policy analysis, with the aim of providing it in a useful way to decision-makers confronting the coupled challenges of future food, energy, water, climate and air pollution (among others). The CGCS also interacts with complementary MIT efforts in the Environmental Solutions Initiative, the Energy Initiative, and the Earth Resources Laboratory.

Given that cutting-edge research about carbon capture is occurring at MIT, you might want to nose around the CGS website to see if your question is being addressed.

It's cooling

Philippe Chantreau at 04:20 AM on 28 November, 2019

Hi,

your comment indicates a lack of familiarity with paleoclimate data and what the science shows for the the more recent times. The moderator's suggestions are good places to start.

It's a 1500 year cycle

Philippe Chantreau at 08:24 AM on 9 November, 2019

A.L "1,470 year lunar induced climate cycle."The chief hypotheses on D.O. events and Bond events involve long term ocean currents and deep mixing events, or fresh water injections, not the moon. Whereas I found a wealth of papers involving oceanic processes, I could not find one mentioning a lunar component.

https://journals.ametsoc.org/doi/full/10.1175/JCLI3437.1

https://authors.library.caltech.edu/16947/1/Eisenman2009p6441Paleoceanography.pdf

https://www.sciencedirect.com/science/article/pii/S0277379117310351

It's the sun

scaddenp at 12:55 PM on 7 November, 2019

socialfox - estimates of climate sensitivity seek to answer what would the change of temperature for a given effective increase in radiation at TOA. Changes in GHG concentration, albedo are back-calculated to an effective change in TOA radiation. ie. As if the incoming solar radiation was changing. The direct contribution to radiative flux from a change in GHG is a known quantity (~4W/m2 for a doubling, which falls out the Radiative Transfer Equations and has been empirically verified in various ways). It is not something deduced from the temperature response, but resultant feedbacks (water vapour, albedo, cloud cover) that contribute to actual change in temperature are not well known and hence the wide range of estimates for climate sensitivity. Climate sensitivity is estimated from a variety of methods including paleoclimate and models.

Note that models do not assume a climate sensitivity - it is an emergent property from the model so I dont see the circularity.

CO2 was higher in the past

nyood at 04:18 AM on 7 November, 2019

@MA Rodger

(1a) "To present a value for CO2 forcing without providing evidential support is not axiomatic,
either in the sense of it being self-evident or (probably in the sense you intend) unquestioningly-evident.
The evidence can be presented should you so wish and, uncontroversially beyond-question, it is correct.

You yourself present @92 an unsupported evaluation of CO2 forcing, providing a maximum value which appears novel and controversial in the extreme.
You fail to present any evidential support which in the circumstance is turning this discussion into a pantomime.
Perhaps you could correct the untenable postion you create for yourself by providing that missing evidence."

(1a) The evidence that i imagine you would provide, will all result in the question: What is missing? This is manifested in the fact that you will get no exact value for CO2 sensitivity, despite known elemental spectral laws regarding infrared absorption. In other words: We are still estimating with 1,5°C - 4,5°C per doubling (?).

The theory that CO2 reaches a "saturation" already, is just the most likely aproach to me. However the forcings of HHE/LPC could be even that strong
that they shrink down all other factors making them neglectable, not "needing" any other explanation to temperature.

The major evidence i can deliver here is the fact that the so called saturation for each GHG is one of the known unkwons and that there are countless debates
on this issue, underlining how unsolved this whole matter is.

"(1b) Your confused statements regarding HHE/LPC appear to contrdict the geographical situation as commonly understood,
in that the "Land mass" Gondwawa sits static over the "Polar Circle" throughtout this period.
You need to consider how it is your LPC appears then disappears within this period when the contition you say causes LPC remains unchanging?"

(1b) I see no contradiction, in my former post i gave you the 2 links with the continental distribution, matching my theory.(Ordovizium, Silur)

I see what you are getting at though wih Schwanck slide 11: The pictures with the "paleo glacial reconstruction". They use a static continental distribution here. It is more likely that the continents were merging towards the hirnation. In a larger perspective the continents definetly move towards the pole, documented by the ordovician with the silurian as a whole. The ice needs to build up and the Boda event interrupted the glaciation process by reducing ice albedo.

"(2) Your cut-&-paste from the Schwark & Bauersachs slides appears particularly inept as support for your assertion "in fact it doubts CO2 as a driver."
If you, for instance, examine Slide 11 you will see your assertion is fundamentally contradicted."

What is contradicted here? Slide 11 shows the Boda event and its CO2 emissions, the CO2 does not matter to me, regarding temperature, the factors that matter are albedo reducing ashes and dust.

If you are refering to this sentence on page 11: "atmospheric emission of large amounts of CO2 and subsequent climate warming, and.."

Then i can only tell you that Schwarck et.al are using the neglectable CO2 sensitivity axiomata here. The reason why the Katian doubts ´CO2 as a driver´ is because it marks, with all other epoches preceeding the LPC event, the time where CO2 fails to work as assumed. Where should it show its significant forcing if not here?

"(3) Here you really do dip into uncomprehensibility. Do note that the Schwark & Bauersachs slides do not ever say CO2
dropped to present atmospheric levels 400-odd million years ago.
The statement you misread from Slide 23 says purely that CO2 varied "between 8-16 x PAL and near PAL."
The value 1500ppm can be taken from their Slide 11."

(3) Well, it does not matter to me, if you want it can be 1500ppm, i would not consider that close to PAL though. PAL would just makes sense to me since the ordovician

is compareable to all other LPC events.

Near Pal makes sense to me because it would reach common glacial CO2 levels. I have not enough knowledge of solubility.

Near Pal is enough for me to support the theory when it comes to: All equilibrium events and the transitions inbetween happen in the same fashion, despite varying CO levels.

"(4) If it is not land at the polar circle that creates your LPC condition; if it is ice-covered land,
you do then reqire to explain the forcing that allows the growth/shrinkage of that ice.
And in doing so, your theory now lacking the tectonic element, do consider that you are now describing a climate feedback not a climate forcing."

The factor that you are missing here is indeed a fundamental one. It is the fact that snow will not accumulate ice sheets on the sea.
The double proof for this is the arctic sea, with Greenland within the polar circle.

In fact with your misunderstanding here it makes me wonder if continental drift as a time dependet factor is included in the prognostications and not only be representd by the, in itself correctly implemented, ice albedo.

In other words:Fundamently excluding a long term factor of warming.

CO2 was higher in the past

nyood at 05:28 AM on 5 November, 2019

"(1) The total climate forcing from 6000ppm CO2 is very roughly 40Wm^-2. There is no evidence
to suggest that climate was impacted by such forcings (from any source) during the Ordovician."

(1) The first sentence is axiomaticly using an estimated forcing of CO2 and therefore is a statement, though the consequences you state are true (none).
I state that CO2 forcing is max 1°C, reaching saturation with roughly PAL levels, pretty much always or already.

The Second sentence is true, the forcings that Do determine climate Temperature (T) are the two equilibrium forces
hothouse effect (HHE) and high landmass ratio within polar circles (LPC).
The faint sun paradox (FSP) underlines the strength and dominance of the terrestial forcings by allowing
the orrdovician-silurian events, HHE - LPC - HHE, to happen within the same T amplitude of all compareable HHE and LPC events untill today.
Neglecting CO2 and reducing the FPS or -4% TPI, in its forcings.

On top of that you devaluate some of your own arguments brought up in the coming sections. According to (1) you do not allow yourself any comparison from there on.

"(2) According to your cited reference (slides 11 & 14), the period with elevated CO2 significantly above 4000ppm
coincides with the Katian, a period of warming."

(2)This sentence has no expressiveness. HHE is happening anyways before and after the LPC.
The Katian documents the late transition state towards an LPC, in fact it doubts CO2 as a driver.
The discrepancy between assumed CO2 forcing and T is underlined by the general high CO2 level in the atmosphere, the planet will reach a glaciation from here on, to develop extreme ice shields despite CO2 levels this high. The FPS is solved as mentioned.
Furthermore forces mentioned in the Schwarck study explain the Katian warming already:
" Bodaevent:
Continental Flood Basalt Province.Alternatively to a bolide impact, LIPs have been postulated as warming triggers."

The forcing here that matters is Ice albedo reduction due to dust and ashes.
We can see this again when younger impacts and events causie warming rather then cooling.
An accumulation of dust and ashes at the poles are the result of a rather quickly cleanse of the atmosphere.

"(3) The period following the Katian sees falling CO2 and falling temperature.
The period of high glaciation during the Himantian sees CO2 estimates
dropping to perhaps 1500ppm. Relative to our recent ice ages with 180ppm CO2,
the Himantian CO2 forcing would thus be perhaps +11Wm^-2 while the relative solar forcing would be -8Wm^-2."

(3) "dropping to perhaps 1500ppm". The Schwarck study claims PAL up to x6 till x20. Please specify "perhaps"
and clarify why it is not PAL but minimum PAL x3 according to you. Where are Schwank et.al wrong ?

Reminding here that the level of CO2 does not matter in the first place unless it is below PAL (max -1°C), using my axioms.

Again you apply axiomatical values, which are not needed to explain temperatures, you are still using the FSP as a theory support, or to bring it in an equilibrium with
CO2 forcing, by trying to "ramp up" CO2 to a minimum of 1500ppm. Ironically this opposites many attempts
that try to lower CO2 to explain why a glaciation happens, despite ~6000ppm before and after the glaciation, in the first place. These views higlight the needs to explain CO2 forcings as assumed (too high).

"(4) Your assertion @89 is that the major forcing of climate is the tectonic positioning of land over polar regions.
Yet there was such land over polar regions throughout the Ordovician when these great swings of climate appear suggesting
the climate was being forced by entirely different mechnisms.

I would therefore suggest you have failed to provide any support for your assertion "CO2 is no driver at all." "

(4)This is partly true, as strong as it is the Ice has to build up, which happens very quickly in the hirnation, after the Bodaevent.
The middle to late ordovician is in transition, the continental drift towards the pole is remarkable.
Which is documented with the Silurian:

Ordovizium

Silur

Furthermore one has to take in account the varying lengths of time periods. The ordovician has been added historicaly,
it was included in the silurian before, therefore this interesting periods are "staunched".

Antarctica shows a trend towards having a "drop back" to the south pole, mentioned in the devonian and possible in the jurassic.
Maybe this happened here too and we need more accurate paleogeorgraphic data.

Answering two other comments here made by other users:

89.Moderator response:

"[PS] This is heading way into sloganeering territory. You are selecting only observations that support your ideas and ignoring completely all others. Science does not operate that like.
You cannot ignore measured increase in downwelling radiation, conservation of energy, nor explain past climate change with hand-wavy statements that violate physics.
If you have a theory that can match all observations, simpler and with better precision than current theory and concordant with laws of physics then by all means publish. Meanwhile,
current climate theory is the one that matches Occams razor. No more half-baked sophistry please."

My theory already has a better explanation with its radical attempt, that is the whole point. This is not "sloganeering" it is just a very radical attempt so it asks for situations where we have evidence that show CO2 as a significant driver, relating to topic.
I understand that my radical attempt makes it easy for me but i have to insist on the fairness that i am allowed to show that radical assumptions that i made, make more sense then your axiomatical assumptions.
There is the inherit problem that we eventualy go off topic but i have to ask you at this point which laws and forcings (radiation, energy conservation) are ignored by me in which way ?
I ignore factors as far as they allow me, hence ockham.
I insinuate that your axioms make less sence then mine. Your critisicsm lacks precission at this stage, when it comes to why my radical assumptions are not allowed and where they are not concordant with laws of physics.

90. Eclectic:

"Nyood, the importance of CO2 as a driver of climate, is supported by (A) theoretical calculations [Arrhenius and later scientists]; is supported by (B) experimental evidence; is supported by
(C) observational evidence; and is supported by (D) geological evidence. In other words, the mainstream science developed during the past 200 years.

The principle of Occam's Razor is a often a helpful guide to thinking : it is not in itself evidence and it is not in itself a method of proof.

Ockham (or Occam) did not support the cutting off or ignoring of evidence. Newton and Einstein did not ignore evidence. Nyood, why do you choose to ignore evidence?"

(A) Arrhenius,Planck Feldmann et.al give a frame, it is known that we can not apply CO2 with a clear value (uncertainty). This leads to a Saturation and or Lindzen et.al and therefore inevitable offtopic, as much as i am willing to discuss it.

(B) same as (A)

(C) I clame that observational evidence support my theory today: Dramatic CO2 increase with a moderate warming trend. My initial post was rightfully snipped of modern time references as offtopic.

(D) Geological evidence is the core of the LPC theory.

Climate's changed before

Eclectic at 19:02 PM on 28 October, 2019

TVC15 @795 ,

I am assuming that you are dealing with a single denialist who tries to bury you under a blathering gush of Gish Gallop.

IMO, best to challenge him on just a few points of his gush :-

(A) Planetary surface temperatures show a good correlation with the *combined* effects of changes in solar output and variations in atmospheric CO2 level. Examples: look at the cooler/warmer periods of the Ordovician Age and also the Carboniferous Age, as well as the Cenozoic recently. Sometimes the CO2 rise was caused by the temperature rise, and sometimes (such as the last 150 years) the CO2 rise preceded & caused the temperature rise.

[to him] "Question: Why are you apparently unaware of all that paleo evidence?"

(B) We know the surface temperature is rising, because [i] satellite evidence shows land and sea ice is melting, and [ii] satellite and tide-gauge evidence shows rising sea level, and [iii] thermometers confirm the rising temperature (a rise now of almost 1 degree since reliable general measurements commenced).

[to him] 'If you cannot understand such basic science, then your "can't feel it" opinion is worth nothing.'

(C) The scientists have looked into all sorts of factors that might influence climate (ranging from clouds and cosmic rays, to greenhouse gasses and albedo changes).

[to him] "If you yourself have discovered a vitally important factor they overlooked, then [i] tell us what it is, and [ii] write to the National Academy of Sciences, and explain to them what morons they all have been for missing such a basic factor, and (iii) start planning how to spend all the Nobel Prize money that you will be awarded from the astounded and delighted Nobel Committee ! .....And good luck with that, Mr Unappreciated Genius."

(Doubtless he will start shifting goalposts, and/or go into strawman arguments, and/or go into Conspiracy Mode.)

The upcoming ice age has been postponed indefinitely

Daniel Bailey at 08:53 AM on 14 October, 2019

In response to your question about the timing of the next potential glacial phase inception, here's what the AR5, WG1, Chapter 5 has to say about that:

"It is virtually certain that orbital forcing will be unable to trigger widespread glaciation during the next 1000 years. Paleoclimate records indicate that, for orbital configurations close to the present one, glacial inceptions only occurred for atmospheric CO2 concentrations significantly lower than pre-industrial levels. Climate models simulate no glacial inception during the next 50,000 years if CO2 concentrations remain above 300 ppm. {5.8.3, Box 6.2}"

LINK

Further:

"Even in the absence of human perturbations no substantial build-up of ice sheets would occur within the next several thousand years and that the current interglacial would probably last for another 50,000 years. However, moderate anthropogenic cumulative CO2 emissions of 1,000 to 1,500 gigatonnes of carbon will postpone the next glacial inception by at least 100,000 years....under natural conditions alone the Earth system would be expected to remain in the present delicately balanced interglacial climate state, steering clear of both large-scale glaciation of the Northern Hemisphere and its complete deglaciation, for an unusually long time"

SOURCE

Looking beyond that, research has found that the ability to offset the next 5 glacial phase inceptions lies within the purview of humans:

"Our research shows why atmospheric CO2 will not return to pre-industrial levels after we stop burning fossil fuels. It shows that it if we use up all known fossil fuels it doesn't matter at what rate we burn them.
The result would be the same if we burned them at present rates or at more moderate rates; we would still get the same eventual ice-age-prevention result."

And

"Burning all recoverable fossil fuels could lead to avoidance of the next five ice ages."

SOURCE

Welcome to Skeptical Science

Eclectic at 13:18 PM on 7 October, 2019

Carol @67 ,

it would be helpful if you gave some indications of your initial thoughts based on your own general knowledge of modelling. And on what practical benefits might be expected from an examination of Eyring's ideas. [ Like you, I have only read the paper's Abstract and some minimal commentary. ]

Pragmatically, climate models seek to assess climate sensitivity (transient and equilibrium). As you will find elsewhere in SkepticalScience articles, the paleo climate evidence points to an ECS of around 3 degrees for CO2 doubling. And the modern historical evidence (planetary surface temperatures during the past 150 years) shows a rise of nearly 1K for a CO2 rise of "halfway to doubling" ~ which indicates a Transient CS of nearly 2K . . . and presumably an ECS close to 3K , as well.

As Greta Thunberg might say :- We should be putting on our running shoes in dealing with the global warming, regardless of whether the latest cimate models come up with an ECS of 2.5 or 5 degrees. ( The latter figure does seem surprisingly high, and may as critics suggest, derive from inaccurate cloud factors. )

2.5 degrees is quite bad enough !

Climate's changed before

Daniel Bailey at 00:36 AM on 25 September, 2019

"Alaskan Glaciers started receding big time around 1750 to 1900"

As opposed to those promoting misinformation, looking at the full context of the Holocene, Alaska glaciers have only been recently declining, reversing a 8,000 year period of growth and expansion:

Per McKay et al 2018 - The Onset and Rate of Holocene Neoglacial Cooling in the Arctic

"Arctic summer temperatures have decreased for the past 8,000 years, before rapidly warming over the past century. As temperatures cooled, glaciers that had melted began to regrow throughout the Arctic, a phenomenon and a time interval known as Neoglaciation.
This study seeks to understand the nature of this cooling and whether or not this indicates a tipping point in the climate system. Specifically, we use a large database of records from ice cores, lakes, ocean sediment, and more paleoclimate archives to detect patterns of cooling. We investigate these patterns, and climate model simulations, to determine what parts of the Arctic experienced Neoglaciation at the same time, how rapidly it cooled, and what climate models indicate about the causes of cooling.
We find that the Arctic did not cool simultaneously, but different regions cooled at different times and that the climate models perform well when simulating both the timing and amount of Arctic cooling."

Full copy available here.

Further, recent climate warming in the central Yukon region has surpassed the warmest temperatures experienced in the previous 13,600 years (and therefore likely the past 100,000 years).

Porter et al 2019 - Recent summer warming in northwestern Canada exceeds the Holocene thermal maximum

News release here.

We're heading into an ice age

Eclectic at 00:18 AM on 25 September, 2019

AlexDeBastiat @395 ,

Of the glaciation/deglaciation cycles of the last million years, each cycle has been unique in structure, because the precise relations of orbital eccentricity and planetary tilt have been subtly different.

So every cycle has been an "N of 1" . Yet the paleo evidence shows that these climate variations have nevertheless operated within narrow limits of conformation. And from those past cases we know that the present Interglacial would "naturally" last something upwards of 25,000 years without the human intervention which has now occurred. ( It is perhaps rather too early to say whether the current high levels of CO2 will cause a complete "skip" of the next scheduled glaciation. )

Alex , if you have some definite contrary evidence (i.e. a scientific paper in a respected journal) then please cite it.

Alex , your third paragraph is rather jumbled in its ideas. Could you please clarify what you mean?

On your fourth paragraph: I would be interested to hear whether (and how ) you would compare the dangers to humanity from the present-century very rapid global warming . . . compared with the dangers to humanity from a very slow ( 10,000 to 20,000+ years' duration ) of global cooling. [Though this cooling scenario has now become abstract & hypothetical.]

Basically, I am thinking that 10,000+ years is plenty of time for the human race to find technological solutions in dealing with such cooling . . . or perhaps even to revert to low-tech methods such as the well-proven anti-cooling technique involving burning a small number of gigatons of coal !

On the other hand: for dealing with the immediate & very pressing problems of rapid global warming during the next 50+ years ~ our politicians seem paralysed like rabbits in a spotlight.

IPCC's land report showed we're entering an era of damage control

nigelj at 07:05 AM on 2 September, 2019

Driving By @14 was perhaps a bit snarky, but does raise a very interesting and pertinent issue on diet. Dietary advice is indeed very contradictory, with seemingly well qualified people promoting diets that are low in meat and fat consumption, like the Mediterranean diet, and vegean diets (no meat) and others promoting high meat and fat diets like Atkins, Ketosis, and the Paleo Diet (technically a high fat diet but people will achieve this with higher meat consumption).

People must be utterly confused, and plenty express this on websites.

The high meat diets are in total contradiction to advice to reduce meat consumption for the good of the planet.

Personally I think moderately low meat mediterranean diet makes the most sense all things considered. Italians and Greeks apparently have good health and longevity. Humans are omnivores.

While meat is an inefficient use of resources, many grasslands grazed by cattle dont really suit crop production, so this suggests to me the only practical answer is moderately low meat diet.

Medieval Warm Period was warmer

Daniel Bailey at 08:20 AM on 27 August, 2019

Specifics on proxy datasets can be found here.

Medieval Warm Period was warmer

scaddenp at 08:10 AM on 27 August, 2019

yes. Where no temperature measurements exist, then proxies are all you have.

Dont let a denier take you down the path of believing that climate theory depending on paleoclimate studies. Paleoclimate studies are useful testing grounds - if our current understanding of climate cannot reproduce measurements of temperature given the uncertaintites in the temperature measurement and our understanding of the forcings operating at the time, then the theory would be in trouble. Not the case. Paleoclimate is also useful in constraining climate sensitivity. However, uncertainties in estimating solar output, aerosols, albedo and temperature all create significant limits compared to analysing the physics of the climate system today.

Residence Time and Prof Essenhigh

daveburton at 21:52 PM on 25 August, 2019

Eclectic wrote, "your heated-wire analogy is even wider of the mark..."

It is just a simple example illustrating a general principle. It's how negative feedback systems work. If the removal rate increases with system output level, that's a negative feedback mechanism. A constant forcing input will then result in a plateau at "equilibrium," where the negative feedback has caught up with the constant input.

That's true when the input forcing is energy added to your toaster via electricity, and the negative feedback mechanism is radiative & convective heat loss from a nichrome wire.

It's also true when the input forcing is CO2 added to the atmosphere, and the negative feedback is CO2 removal from the atmosphere via dissolution in the oceans and terrestrial plant uptake.

The principle is true regardless of whether the negative feedback is linear or nonlinear. For the nichrome wire example, there are actually three significant negative feedbacks, all with different transfer functions: radiative heat loss goes up in proportion to the 4th power of the temperature relative to 0K, convective heat loss goes up in approximate proportion to the temperature difference between the wire and ambient air, and the resistance of the wire also goes up with temperature. The fact that all three have different-shaped transfer functions doesn't affect the conclusion: because they are negative feedbacks, a constant input (forcing) must result in a plateuing output, gradually approaching equilibrium.

Eclectic continued, "The design of the Simple Model fits at best tangentially with physical reality."

It fits extremely well for the period for which we have accurate measurements:

Eclectic continued, "nor do we have the luxury of time to sit back and observe another 40 years or so, as the Simple Model diverges from the (complex) real world."

Well, I obviously don't, at my age.

But mankind does have that luxury, and you should not expect Roy's Simple Model to diverge much from reality over the next 40 years. It is the "long, fat tail" (due to increased carbon levels in non-atmospheric reservoirs) which is not modeled by the Simple Model. Regardless of what happens with CO2 emission rates, CO2 removal over the next 40 years will be dominated by the removal mechanisms which the Simple Model models well.

Eclectic continued, "the paleo evidence demonstrates the falsity of Spencer's too-simple Simple Model."

All models are false, but some are useful. Roy's Simple Model is very useful. It is a very good fit to measured reality, and it will continue to be a good fit as long as the CO2 removal mechanisms which are currently most important continue to be most important. When CO2 levels drop below 300 ppmv, and the accumulation of anthropogenic carbon in non-atmospheric reservoirs becomes an important factor affecting atmospheric CO2 levels, then his Simple Model will diverge from reality.

MA Roger wrote, "Yes, the oceans are big. Yes, the oceans contain contain sixty-times the carbon found in the pre-industrian atmosphere (which was in full equilibrium with the oceans). But what has that got to do with your "fact"?"

Mankind has increased CO2 level in the atmosphere by about 47%. We've increased carbon content in the oceans by only about 0.4%.

So, why does that matter? Because it is that accumulation of carbon in non-atmospheric reservoirs that is not modeled by Roy's Simple Model. In other words, his Simple Model assumes the other carbon reservoirs have infinite capacity.

That's a pretty good simplifying assumption, as long as the anthropogenic increase in atmospheric CO2 dwarfs the anthropogenic increase in carbon in other reservoirs. It will diverge from approximating reality during the "long, fat tail," when the anthropogenic increment in atmospheric carbon dioxide no longer dwarfs the anthropogenic increase in carbon in other reservoirs.

MA Roger wrote, "it is very odd that they would ever allow atmospheric levels to remain constant while the ocean absorbed a large constant flux of dissolving CO2."

Atmospheric levels will remain constant when transfer of carbon to the oceans and other carbon reservoirs removes CO2 from tha air as quickly as anthropogenic emissions are adding it. (They're currently removing it only about half as fast as we're adding it.)

MA Roger asked, "Have you actually examined the workings of Spencer's model?"

Of course.

MA Roger wrote, "If you set the future anthropogenic emissions to a fixed value... atmospheric CO2 levels tend to a constant value"

Which is, of course, correct.

MA Roger wrote, "while negative emissions, suck out 15Gt(C)/yr and by AD2191 the atmosphere is entirely denuded of CO2. daveburton, doesn't that strike you as "very odd"?"

Not at all. If you start with a physically impossible assumption, you get a physically impossible result. The only thing I can think of which could possibly remove a net 15 GtC/year from the atmosphere when CO2 levels are below 300 ppmv, is some idiot genetically engineering a fast-growing, fast-propagating C4 tree.

Please don't do that! The Earth doesn't need another K-T Extinction!

Residence Time and Prof Essenhigh

Eclectic at 05:17 AM on 24 August, 2019

Sorry, Daveburton, but your heated-wire analogy is even wider of the mark than Dr Spencer's much-too-simple Simple Model.

The design of the Simple Model fits at best tangentially with physical reality. And 40 years is a short period — nor do we have the luxury of time to sit back and observe another 40 years or so, as the Simple Model diverges from the (complex) real world.

As MA Rodger points out : the paleo evidence demonstrates the falsity of Spencer's too-simple Simple Model.

Residence Time and Prof Essenhigh

MA Rodger at 19:03 PM on 23 August, 2019

daveburton @27,

The problem is as described by Eclectic @28&30. Roy Spencer is not renowned for errorless analysis. This 2018 blog of Spencer's you rely on is no more than an exercise in curve-fitting that leads to the ridiculous conclusion that if humanity restricts itself to pumping 10Gt(C)/year of CO2 into the atmosphere (as it did in 2018), continuing year-after-year for ever-&-ever-&-ever, the atmospheric CO2 level will stablise over 200 years at 500ppm(v) CO2.

This is plainly nonsense. Where does all this extra carbon accumulate? And if paleoclimate studies show atmospheric CO2 levels in past eons at 2,000ppm for over a hundred million years, were did the carbon come from to maintain such levels? According to Spencer's model, simply to maintain it at 500ppm over such a period would require emissions upward of 1Zt(C). I'm pretty sure the planet doesn't contain that much carbon!!

You are perhaps correct to suggest that many misinterpret the Airbourne Fraction which is simply a product of our rising emissions. It is not a subject much discussed beyond the Af concept itself. In terms of the draw-down mechanism, Af is a very poor concept to start from. So in Af terms in 2018, that 57% of 2018 CO2 emissions drawn-down out of the atmosphere is better seen as comprising something like a draw-down of 4% of the emissions 2014-18, 2.5% of the emissions 1999-2013, 0.6% of the emissions 1919-98, etc. These approximate numbers I obtain by scaling one of the 1000_cswv plots in Fig 1 of Archer et al (2009) 'Atmospheric Lifetime of Fossil Fuel Carbon Dioxide' which models a single 1,000Gt(C) impulse. The draw-down dynamics under the gradual release of AGW mean these numbers will not entirely match the AGW numbers, but they do well enough as a rough guide.

2019 SkS Weekly Climate Change & Global Warming Digest #30

nigelj at 12:28 PM on 2 August, 2019

Werner Hartl @16

"2) Have any controlled experiments been done to test the theory? For example, with IR transparently enclosed identical boxes set in a field with varying amounts of CO2 and temperature monitored."

Lab experiments have conclusively demonstrated CO2 is a greenhouse gas basically by shining light sources on canisters of CO2 and other gases and this goes back literally centuries. Easily enough googled and lots of youtube videos.

3) Same experiment as 2) under lab conditions with temperature change predicted by theory before the experiment?

Not possible except very crudely in that more CO2 generates more warming. The temperature changes predicted for the earths atmosphere as CO2 increases are a function of a huge vertical depth of atmosphere and compounding factors like convection, clouds and positive feedbacks that cannot be emulated in a glass container in a lab. It relies on complicated physics, modelling and paleo climate evidence (and we have some good evidence).

2019 SkS Weekly Climate Change & Global Warming Digest #28

Eclectic at 10:44 AM on 16 July, 2019

Nigelj , the "cosmic ray" article has been headlined as a Breakthrough , per that scrupulously-scientific and just-slightly propagandist organization, the GWPF. Also taken up by ClimateDepot & other bloggy deniosphere sites.

On somewhat tenuous grounds, the academicians at Kobe University etc have suggested that the latest geomagnetic reversal ( 780,000 years ago ) had — via a temporary increase in cosmic ray impingement — produced a variation, for several thousand years, in the Winter Monsoon in North-East Asia (but little effect on the Summer Monsoon).

As yet, I have been unable to see that this localized effect so very long ago, could have more than zero relevance to modern global climate or even the climate of the last 100,000 years. We already have experimental, historical, and paleological evidence that Cosmic Rays have negligible effect on world climate.

The GWPF seems to be scraping the bottom of the barrel, in its ongoing attempts to find a whisker of doubt about mainstream climate science. Not that such attempts are anything new, from the GWPF. As yet, the GWPF's batting rate is steady at Zero.

Climate sensitivity is low

michael sweet at 09:32 AM on 14 July, 2019

Penguin,

In hte paper you cite they claim that climate sensitivity is derived completely from cliamte models. That is false. there are several ways to derive climate sensitivity from data includig paleoclimate data. I note they provide no citations to support their claims. They will only be read by skeptics.

They assume that the change in cloud cover forces the change in temperature. That is completely backwards. Cloud cover is a response to the change i temperature and not the casue of the change. In order to chage the temperature you have to add energy. Changes in clouds do not add energy.

It's the sun

Eclectic at 22:12 PM on 10 July, 2019

ThirdStone @1266 ,

the ratio of area of a disc (receiving sunshine) to the area of a sphere is 1:4 and hence the division by 4

The scientists look very carefully at sun activity, and find that the 11-year cycle of solar activity is too slight to produce noticeable cyclic fluctuation in climate. Or did you have some other factor in mind?

"Cosmic Rays" are a failed hypothesis for climate change, and can be dismissed. A triple fail, because (A) CR effects appear non-existent for the period (since mid-20th Century) that CR levels have been measured directly, and (B) likewise the paleological (proxy) measurements of CR variation show no appreciable link to climate changes, and (C) the 2016 experiments at CERN show negligible CR effect on cloud nucleation (negligible in comparison with the nucleation from marine-origin particles). As they say: Cosmic Rays were a "Nice Try" as an idea for climate influence, but when tested against reality, they were a major fail not just on one way but on three separate ways of testing.

Holocene Optimum was warmer

Phaedrus1 at 21:29 PM on 21 June, 2019

From the National Climate Data Center:

Paleoclimatologists have long suspected that the "middle Holocene," a period roughly from 7,000 to 5,000 years ago, was warmer than the present day. Terms like the Altithermal or Hypsithermal or Climatic Optimum have all been used to refer to this warm period that marked the middle of the current interglacial period. Today, however, we know that these terms are obsolete and that the truth of the Holocene is more complicated than originally believed.
What is most remarkable about the mid-Holocene is that we now have a good understanding of both the global patterns of temperature change during that period and what caused them. It appears clear that changes in Earth's orbit have operated slowly over thousands and millions of years to change the amount of solar radiation reaching each latitudinal band of Earth during each month. These orbital changes can be easily calculated and predict that the Northern Hemisphere should have been warmer than today during the mid-Holocene in the summer and colder in the winter. The combination of warmer summers and colder winters is apparent for some regions in the proxy records and model simulations. There are some important exceptions to this pattern, however, including colder summers in the monsoon regions of Africa and Asia due to stronger monsoons with associated increased cloud cover during the mid-Holocene, and warmer winters at high latitudes due to reduction of winter sea ice cover caused by more summer melting.
In summary, the mid-Holocene, roughly 6,000 years ago, was generally warmer than today during summer in the Northern Hemisphere. In some locations, this could be true for winter as well. Moreover, we clearly know the cause of this natural warming, and we know without doubt that this proven "astronomical" climate forcing mechanism cannot be responsible for the warming over the last 100 years.

https://www.ncdc.noaa.gov/global-warming/mid-holocene-warm-period

Water vapor is the most powerful greenhouse gas

Eclectic at 22:05 PM on 13 June, 2019

3-d Construct @344 ,

I apologize for my inexpert comments : but I gather that you are in that state of mind (analogous to writer's block) where useful thoughts may be triggered by re-encountering stuff you've already been acquainted with . . . or even by comments which are vapid & klutzy.

So :-

* Quantification. Exactly how important is H2O in the stratosphere? In absolute terms or relative terms. Lower or upper stratosphere. Re-visit lapse rates and TOA concepts?

* Quantification of "supersaturated" water vapor at high altitude. Important, or too transient?

* There are 350 million square Km of ocean surface interacting with a thin rind [a few dozen Km] of planetary atmosphere. Is the high-altitude human contribution of water vapor genuinely significant?

* In comparison, there were subtle but measurable alterations in regional heat flux for the [ocean-free] expanse of the continental USA during the 3-day "shutdown" of jet flights immediately following the 911 terrorist event. IIRC, the lack of contrails did have the expected effect : cooler nights, warmer days. But of course the other 98% of the planet surface has more ocean and/or less air traffic.

* I gather Hansen has rather "walked back" his earlier comments about the dangers of runaway warming . . . and, as you say, the paleo evidence points to "moderate stability/resiliency" of global surface temperature.

State of the climate: Heat across Earth’s surface and oceans mark early 2019

RedBaron at 08:41 AM on 12 June, 2019

@swampfox,

You make an interesting hypothesis. However, your hypothesis lacks any evidence for it, and has quite a bit of evidence against it. So I would suspect you are a very very long way from supporting your assertions.

More importantly as it applies to agriculture though, those who claim moving their cattle daily is indeed biomimicry are obtaining spectacularly better results than those who fence their cattle near streams and leave them there.

There are huge improvements to both the animals and the grasses and forbs of the prairie and even a measurable increase in carbon sequestration of the soil when managed holitically with our new understanding of grassland ecology.

We have fossilized paleosoil evidence:

Cenozoic Expansion of Grasslands and Climatic Cooling

We have observational evidence from YellowStone how predators forced herbivores away from lingering near rivers and how that improves ecosystem function.

How Wolves Change Rivers

In agriculture using biomimicry we have measurable evidence from modern tallgrass prairies:

Grazing management impacts on vegetation, soil biota and soil chemical,
physical and hydrological properties in tall grass prairie

and from drier shortgrass prairie:

Effect of grazing on soil-water content in semiarid rangelands of southeast Idaho

Notice on the last two that there was even an improvement over the controls without any grazing.

We even have evidence that many prairie grasses will simply die out if not periodically grazed or burned. This due to the grasses going moribund and choking on old material.

Fire is a big component to the success of grasslands, large or small. Controlled burns, with a permit, are recommended every 4–8 years (after two growth seasons) to burn away dead plants; prevent certain other plants from encroaching (such as trees) and release nutrients into the ground to encourage new growth. A much more wildlife habitat friendly alternative to burning every 4–8 years is to burn 1/4 to 1/8 of a tract every year. This will leave wildlife a home every year and still accomplish the task of burning. The Native Americans may also have used the burns to control pests such as ticks. If controlled burns are not possible, rotational mowing is recommended as a substitute.
One of the newer methods available is holistic management, which uses livestock as a substitute for the keystone species such as bison. This allows the rotational mowing to be done by animals which in turn mimics nature more closely. Holistic management also can use fire as a tool, but in a more limited way and in combination with the mowing done by animals.[1]

So the weight of the evidence leads one away from the understanding you have and towards the new more modern understandings we recently discovered in just the last few decades.

Increasing CO2 has little to no effect

scaddenp at 07:52 AM on 10 June, 2019

ebelba - sorry for delay - no internet over weekend. Clouds are indeed one tough issue for feedback predictions. Clouds are both a positive and negative feedback depending on whether high or low. This is not well captured in climate models (cell size in models is too large for the processes involved) so figuring out how that would change with increasing water vapour is challenging. I am not aware that uncertainties for individual components have changed significantly since those published in Fig SPM.5 (see text for sources) of IPCC WG1 or table 8.6 in the main text. Chpt 8 has the main coverage of this. There has been a focus recently on trying to establish empirical constraints via paleoclimate archives and direct observations. For recent work, see for example Dessler and Forster 2018. For paleo, see say Hansen & Sato 2012. Their model/observation fit for a sensitivity around 3 impressed me.

I dont think there is any escaping the problem that governments need to set policy despite stubborn uncertainties in the values of ECS; but need to do this on basis of a best estimates being close to 3.

Tree-rings diverge from temperature after 1960

MA Rodger at 01:25 AM on 9 June, 2019

Tom Janson @87,

If you look (& the paper itself affords the best view) you will see that there is divergence, just not as much and as early as in the OP's figure 1. To quote from the paper:-

"Despite their improved fidelity as hemispheric temperature surrogates, the current generation of tree-ring reconstructions also still show signs of the so-called ‘divergence problem’. This issue, which was first identified in Alaska and then subsequently at many boreal forest sites, refers to a loss of sensitivity exhibited by some temperature-limited tree-ring chronologies starting in the latter half of the 20th century. Filtering the three latest reconstructions to emphasize variability at decadal scales or longer does indeed show they do not track the sharp post-1990 increase in Northern Hemisphere temperatures, and it is evident even in the annual (unfiltered) series that the reconstructions reproduce (incorrectly) only modest warming during this interval (Fig.1b)"

The caption for Fig 1b runs:-

"The three state-of-the-art ‘tree-ring only’ paleo-temperature reconstructions (Schneider et al., 2015; Stoffel et al., 2015; Wilson et al., 2016) compared against mean June-July-August instrumental temperatures averaged over 30º-70ºN land areas (Harris and Jones, 2017)."

And be aware that divergence is not a universal phenomenon but although it is wide-spread enough to appear in any reconstructions that span large areas.

"The existence of the Divergence Problem (DP) is not spatially complete and appears to be more prevalent to some areas. ... Despite this apparent large-scale distribution of the phenomenon, at a site or regional level, the DP is not observed at all studied locations. Moreover, the current body of literature reveals that the DP does not exist at lower latitudes. Therefore, the DP should not be thought of as an endemic large-scale phenomenon with one overriding cause, but rather a local-to-regional-scale phenomenon of tree-growth responses to changing environmental factors including multiple sources and species-specific modification." Büntgen et al (2009)

Tree-rings diverge from temperature after 1960

Daniel Bailey at 11:26 AM on 8 June, 2019

Tree rings are a useful tool, both for the early 20th century (to help ground-truth the overlap period with the instrumental temperature record and to therefore give them weight for before that overlap period) and earlier.

However, scientists have far more proxy records than just tree ring cores. So the arsenal that scientists rely upon has many tools beyond just tree rings.

Temperature measurements began in 1659. Stations were added throughout the centuries since then, becoming a truly global network beginning in 1850. Proxy records extend that record literally many hundreds of millions of years into the past.

Have you read the OP and worked your way through the linked articles and everything discussed in the comments section here? If not, why not?

Climate's changed before

MA Rodger at 23:56 PM on 4 June, 2019

TVC15 @724,

There were of course "EXTREME" climate processes prior to mankind arriving on the scene. These can perhaps be classified into two different groups.

The first can include really big changes but they occur very slowly, although sudden on a geological time-scale. So the end of the last ice age saw a rise of perhaps 6ºC in global temperature over 8,000 years or 55 million years ago the PETM which saw similar temperature rises over 40,000 years (long enough for, for instance, horses to adapt to the temperature increases by slowly evolving from pony-size into the size of large dogs).

The second group are far more sudden, the suddenness often obvious. A big volcanic eruption (Mt Toba 74,000 years ago), a meteor strike, or a sudden influx of fresh water that destabilises ocean currents (as per Dansgaard–Oeschger events). This second group can still have very very big local effects but obvious causes that soon dissipate (althugh D-O events can take 2,000 years to return to the prior climate).

But in all this, I'm not sure what a denialist is trying to argue. If we wait long enough there will eventually be a mega-volcano blow its top, or a big meteor will eventually strike the Earth. (There isn't enough ice about for a D-O event to occur without an ice-age.) So is the denialist suggesting we set about creating our own climatic disaster to allow us to practise for how to respond to the real thing? Or does he want an explanation for every wobbly bit of paleoclimate before he will accept the blindingly obvious fact that it is humanity driving todays warming climate and it will not end well if we don't do something about it?

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

nigelj at 07:50 AM on 1 June, 2019

Higgij

I'm not sure what you are really getting at. I agree with eclectic. However I will throw in a couple of comments:

You expressed a concern that the early IPCC modelling did not predict the "pause" after 1998 (if I interpret you correctly). Scientists have always been up front that modelling cannot accurately predict relatively short periods like 10 years because they are influenced by natural variation. Eg clearly no modelling can predict volcanic eruptions or accurately predict a semi regular cycle like el nino, however modelling can predict longter term trends. In fact the pause does easily fit within error bars of the models see here.

"(F) The earth is just now coming out of a peak in the temperature variations caused by the orbital cycels. "

Not really refer here. Earth has been in a cooling phase for about 5,000 years and this has only been seriously interrupted by the warming spike since 1900.

"(G) When proxy temperature information inherently averages over 1000 years, the indicated peak temperatures over a 100 year period are drastically smoothed and diminished."

There is not enough data to get every short term temperature spike in the paleo record, however I recall reading somewhere that they use a random data gathering process which means its likely any large spike of 100 years would be captured. But even if past temperature record has short periods of rapid warming of 100 years comparable to recent decades since 1900, it would have to have an explanation, possibly intense volcanic activity. Volcanic activity was often very intense and protracted in Earths early history.

Climate Adam reacts to Bill Nye: "The planet's on f@*&ing fire!"

scaddenp at 13:31 PM on 21 May, 2019

Nope, radiative heat loss from earth surface is much larger conductive or convective heat loss. This is simple measurement. I gave you a couple of examples where you could test your theory versus mainline physics.

If you want to test a theory against data, then can I suggest the Desert Rock archive? Not only does it have basic met dat like humidity, temp, wind speed etc, but it has also got instruments measuring incoming and outgoing radiation in various parts of the spectra.

"Climatologists believe that ALL past climate change events were caused by greenhouse gases scares the hell out of me. "

That is a ridiculous claim with no basis at all. A simple read of just the Paleoclimate chapter of any the IPCC WG1 reports would contradict that. You could summarise climate change theory as being that climate (30 year meteorological averages) changes in response to NET forcings. The principal source of forcings are change in solar input (or distribution); change in albedo; or change atmospheric composition. These are not independent variables. I strongly suggest you acquaint yourself with the science by at least looking at an IPCC WG1 report.

PS, also a geologist/geophysicist. I look after a model for thermal evolution of sedimatary basins and the consequent oil/gas generation. Actually mostly past tense - my country has more or less ended petroleum exploration and as from June I am reassigned.

CO2 lags temperature

Sokrates Wonders at 15:05 PM on 17 May, 2019

You can look in Raymond Bradley's Paleoclimatology third edition about dating of ice cores. I think you cannot just compare time scales for different dating methods with one another without having some clear evidence for some time event like an volcanic eruption or similar which enables you to link the time scales together.

CO2 lags temperature

David Kirtley at 09:44 AM on 17 May, 2019

Oops forgot to add link to previous post:

https://www.ncdc.noaa.gov/paleo-search/study/17878

CO2 lags temperature

scaddenp at 07:41 AM on 17 May, 2019

A quick look at the paleoclimate archives shows CO2 data for GRIP and GISP2 though the records are nowhere near as long as those in Antarctica. I am not really sure that I understand the question about the end of the ice-age. The Milankovich forcings that control the broad timing ice ages are not synchronous between hemisphere. Furthermore the events mentioned are regional discursions thought to be driven by combinations of icesheet melting dynamics and oceanic processes. The processes are local not global. That said, the causes of D-O and Heinrich events is not settled science.

Sea level rise predictions are exaggerated

Daniel Bailey at 08:49 AM on 13 May, 2019

Global sea levels are indeed rising, raising concerns about human safety. Some excerpts from the 2018 National Climate Assessment, Volume 2, validated and approved by the Trump Administration:

"Global average sea level has risen by about 7–8 inches (about 16–21 cm) since 1900, with almost half this rise occurring since 1993 as oceans have warmed and land-based ice has melted. Relative to the year 2000, sea level is very likely to rise 1 to 4 feet (0.3 to 1.3 m) by the end of the century.
Emerging science regarding Antarctic ice sheet stability suggests that, for higher scenarios, a rise exceeding 8 feet (2.4 m) by 2100 is physically possible, although the probability of such an extreme outcome cannot currently be assessed."
"Over the first half of this century, the future scenario the world follows has little effect on projected sea level rise due to the inertia in the climate system.
However, the magnitude of human-caused emissions this century significantly affects projections for the second half of the century and beyond.
Relative to the year 2000, global average sea level is very likely to rise by 0.3–0.6 feet (9–18 cm) by 2030, 0.5–1.2 feet (15–38 cm) by 2050, and 1–4 feet (30–130 cm) by 2100.
These estimates are generally consistent with the assumption—possibly flawed—that the relationship between global temperature and global average sea level in the coming century will be similar to that observed over the last two millennia.
These ranges do not, however, capture the full range of physically plausible global average sea level rise over the 21st century.
Several avenues of research, including emerging science on physical feedbacks in the Antarctic ice sheet suggest that global average sea level rise exceeding 8 feet (2.5 m) by 2100 is physically plausible, although its probability cannot currently be assessed."
"Regardless of future scenario, it is extremely likely that global average sea level will continue to rise beyond 2100.
Paleo sea level records suggest that 1.8°F (1°C) of warming may already represent a long-term commitment to more than 20 feet (6 meters) of global average sea level rise; a 3.6°F (2°C) warming represents a 10,000-year commitment to about 80 feet (25 m), and 21st-century emissions consistent with the higher scenario (RCP8.5) represent a 10,000-year commitment to about 125 feet (38 m) of global average sea level rise.
Under 3.6°F (2°C), about one-third of the Antarctic ice sheet and three-fifths of the Greenland ice sheet would ultimately be lost, while under the RCP8.5 scenario, a complete loss of the Greenland ice sheet is projected over about 6,000 years."

https://nca2018.globalchange.gov/chapter/2/

Figure 12-4a is the salient figure, for expected SLR to come (click for bigger image):

(a) Global mean sea level (GMSL) rise from 1800 to 2100, based on Figure 12.2b from 1800 to 2015, the six Interagency GMSL scenarios (navy blue, royal blue, cyan, green, orange, and red curves), the very likely ranges in 2100 for different RCPs (colored boxes), and lines augmenting the very likely ranges by the difference between the median Antarctic contribution of Kopp et al. and the various median Antarctic projections of DeConto and Pollard

There is no consensus

Eclectic at 01:10 AM on 26 April, 2019

Pl @785 ,

1. The original "attractor" theory (held up until the 1930's) was that the Earth's climate was self-correcting i.e. homeostatic within narrow limits. But that was disproven, as experimental & observational & paleo-climatic evidence mounted up. Satellite-based evidence has re-inforced that, too.

2. "Peer influence" is not a problem ~ because genuine scientists have a natural tendency to be contrarian & genuinely skeptical.

The consensus is pretty much unanimous for climatologists, because nowadays (unlike 50 or 100 years ago) the evidence for "CO2/AGW" is conclusive. There are no longer any "alternative theories" that hold any validity ~ the plausible alternative have been disproven (e.g. GW from variation in cosmic ray intensity; homeostatic cloud formation as an "Iris Effect"; long-cycle ocean current effects).

If you take time to learn more about the mechanisms influencing global climate, you will recognize that the (mere handful of) "dissenting" climatologists are offering only empty dissent . . . because they have nothing valid to back up their dissent. They are just running on automatic . . . such as the well-known retired Professor Lindzen, who has an Old Testament religious belief that the Earth has been designed to remain close to the Garden of Eden climate status. A few others suffer from extremist political beliefs, motivating them to cherry-pick / ignore the plain evidence.

Please note that the respected scientific journals welcome dissenting views provided that there is reasonable supportive evidence. (Journals and scientists gain prestige & fame by demonstrating valid contrarian evidence.)

But alas, every contrarian idea has failed the validity test, and there are extremely strong reasons why no "undiscovered" factor exists.

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