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

Recommended supplemtal reading:

Some thoughts on Bret Stephens’ misleading climate take by Brian L Kahn, Medium, Apr 29, 2017

michael sweet at 20:28 PM on 30 April 2017

NY Times hired a hippie puncher to give climate obstructionists cover

Is there a way to write to the NYT if you are not a subscriber?

william5331 at 15:38 PM on 30 April 2017

We're heading into an ice age

Interglacials begin to end, generally, as soon as they reach their peaks. The slide into a glacial is much more gradual that the exit from a glacial As the snow can only accumulate as fast as precipitation exceeds melting of the snow deposited. Of interest is that the amount of warming we have observed is not the amount we have caused. To estimate how much we have caused we have to look at what the temperature would likely be at present without the influence of man. Apparently the interglacial with the Milankovitch cycle most similar to the present one is the interglacial which occured some 400,000 years ago. On this basis we are up to and probably over 2 degrees C. Using this point of view, the sensitivity for doubling Carbon dioxide increases a little since the anthropogenic heating per increas of Carbon dioxide is a little more than if we use the actual increase.

David Lewis at 12:41 PM on 30 April 2017

NY Times hired a hippie puncher to give climate obstructionists cover

After Trump was elected I wanted to support some of the great American insitutions of journalism. I bought a subscription to the NY Times.

I cancelled it when they decided to feature this Stephens clown.

nigelj at 06:37 AM on 30 April 2017

March against madness - denial has pushed scientists out to the streets

OPOF @12, I'm in full agreement about the need for sustainable development goals. I just thought the link was a bit confused, or incomplete on the the forces driving the historical issues and leadership issues they discussed. It was on the right track, but confused.

I think as per my comments above, if you look at history, western society has jumped from one extreme economic or environmental ideology to another over long term time frames, and sometimes "thrown the baby out with the bathwater" in other words we are looking for simplistic answers when none exist. We abandoned capitalism too much, in the 1930's, rather than just modifying some elements, and then went on to abandon the "mixed"economy of the 1960s, not realising some elements of it were very good. "Neoliberalism" has some problems that must be fixed, but we are at risk of throwing out the good elements like free trade.

This is why I admire Scandinavia to some extent, they combine a range of ideas, rather than getting bogged down with labels like capitalism or communism. Theodore Roosevelt seems to have a similar mindset to some extent. I guess this is pragmatism, and even Trump is a pragmatist, but he is making some very poor choices especially regarding the environment (arctic drilling)

Getting back to sustainable development goals, this can embrace a whole range of environmental and economic concerns. Its a no brainer for me, just so obviously needed at a point in human history when its obvious we are having some pretty huge impacts. This is why I despise economic or political ideologies ending with "ism" because we always have to keep open minds and deal effectively with new problems, and fixed ideologies can make that very hard. That's not to say we can work without guiding principles, and government is not the answer to everything either, but it is the answer to certain things and this is where we need better agreement across countries on what this is, and what things should be regulated by governments, and what shouldn't. I'm pretty clear in my mind, and Theodore Roosevelt was.

Regarding marketing and winners. It's interesting because competition has obviously had a positive side, but tends to go wrong if there are no boundaries. It's a case of improving awareness that boundaries are healthy, and not communism or some other "ism".

In fact competition goes most wrong where there is no competition, and you have corporate entities that are monopolies, that effectively become bullies. Again if we have any sense we should put some controls in place, Make no mistake they will keep on producing the goods but their behaviour will be better. History shows this.

It is the big corporations and especially the monopolistic, corporations driving the anti environmental policies. Theres plenty of evidence of this starting with the Koch Brothers. They have huge power.

Where companies are smaller and many are in competition, this is quite effective at forcing them to also behave well enough. Its larger monopolies that can become a real problem.

The less ethical players simply take all this to another level. By legitimising "greed is good" in the 1980s, along with massive financial deregulation, we opened the floodgates to excusing unethical behaviour, that is detrimental to the public good. We saw a perfect example of all this in the 2008 financial crash.

Marketing is a tough issue because it has a good and bad side. It's the price we pay for freedom of speech and a free society. We accept people are entitled to sell their ideas and products, and this is healthy, however the price we pay is all kinds of lies and rorts, and brainwashing. Immediately anyone says we need "controls" over advertising, or some quality standards for free speech, the corporate lobby cry socialism or big government.

Yet while I deplore ideologies like communism, there is nothing wrong with rules of conduct if we want a stable, prosperous society that balances production of goods with honesty of marketing, and a sustainable environment etc. Even our rights to free speech, which I strongly support, come with some unspoken responsibilities, such as a need to avoid verbal abuse and bullying or inciting violence.

vatmark at 06:19 AM on 30 April 2017

Increasing CO2 has little to no effect

It was supposed to say

-It seems like he is saying that if the thermal radiation emitted from the atmosphere decrease, it causes the temperature to increase?

vatmark at 06:18 AM on 30 April 2017

Increasing CO2 has little to no effect

I had a look at the link to general circulation models. After reading that my conclusion is that it seems like we are not much wiser

"For all the millions of hours the modelers had devoted to their computations, in the end they could not say exactly how serious future global warming would be. They could only say that it was almost certain to be bad, and unless strong steps were taken soon, it might well be an appalling catastrophe."

This does not convince me that climate models are doing it right by using backwards calculations where emitted radiation is causing the temperature of layers below.

After reading this I don´t get much wiser either:

https://pubs.giss.nasa.gov/docs/2011/2011_Hansen_ha06510a.pdf

It seems like he is saying that if the thermal radiation emitted from the atmosphere, it causes the temperature to increase?

He says that observed heat from the earth is not in balance, the heat flux from the sun that heats earth is larger than the amount of heat that earth emit to space. I find that logical, the earth is not equally warm throughout, and then it has to emit less energy. Only when the system is equally warm in every point inside, it emits as much heat to space as it receives. If we compare to a steam engine and the troposphere is the waterfilled cylinder, then it has to have an even temperature from the surface all the way up to the tropopause before the heat flux is equal to what the sun deliver to the surface.

I really don´t understand this radiative forcing and radiative imbalance, how does it work? How can less heat emitted from the atmosphere cause more heat elsewhere? The more I read about it, the more confused I get.

Hansen wrote about satellite measurements showing an imbalance of 6.5W/m^2 averaged over 5 years. Then he says it was thought to be implausible and they made instrumentation calibrations to align the devices with what the models say, 0.85W/m^2.

He says that the forcings is known accurately, but when measured it is corrected to follow the models. They don´t correct the models according to measurements?

How can forcings be known accurately if they are not a result of measurements? Not any of the studies show how any numbers of forcing has been achieved. And I can´t find any descriptions of the heat flow the way I think it should be done, or rather, the way I like it. Just using measured temperature to find out how much heat there is in the different parts, and from there you can describe the heat flow. That is how we always have done it, and it works. Steam engine, it works perfectly for earth, why use anything else? My teacher must have been very smart, or dumb enough to keep it simple. I was directed here after talking to people in the march and they couldn´t answer my questions. I thought it was strange, so many people marching for science, but no one knew anything about heat, but they all carried signs about temperature increasing and climate problems. I always thought that the issue was about the atmosphere getting so hot that it came near to surface temperature, from top to bottom, because that is what it takes to heat something up usually. But this is just strange and now I think that it must be a good thing Trump won the election. I thought he said some stupid things, but he seems to act like he knows what he´s doing.

I guess I won´t be coming back here anymore. Good Luck with your campaign, you are going to need it.

vatmark at 04:11 AM on 30 April 2017

Increasing CO2 has little to no effect

Tom Curtis at 11:04 AM on 20 April, 2017
" the formula for radiative forcing was not directly derived from fundamental physics. Rather, the change in Outgoing Long Wave Radiation at the tropopause, as corrected for radiation from the stratosphere after a stratospheric adjustment (which is technically what the formula determines), was calculated across a wide range of representative conditions for the Earth using a variety of radiation models, for different CO2 concentrations."

This seems very odd to me. You use a formula for radiation, not based on fundamental physics?

And the changes in Outgoing Long Wave Radiation is corrected for radiation in the stratosphere, after you adjust the stratosphere in what way?

This is then used to calculate surface temperature, or some influence on it?

Isn´t that an example of doing radiation physics backways? To me it seems like you use the effect as a cause if you start at the last point where radiation leaves the climate system.

Do I understand it right that you adjust stratospheric radiation to co2 concentration, then correct Outgoing Long Wave radiation to that, then use that information as a cause, or part of the cause, of surface temperature?

Is the infrared radiation of the stratosphere the cause of infrared radiation in the tropopause, and the infrared radiation of the tropopause is the cause of infrared radiation from the surface? I see you write radiative forcing, but as I understand it, radiative forcing is still a change of infrared radiation.

Can you connect that to solar radiation? I guess this chain reaction stops at the surface since it is not possible for the surface to have an effect on heat from the sun. I thought a model had to be done in the other way around, you start with the heat source and find the amount of absorbed heat in the surface. Then continue to estimate the heat absorbed by the atmospheres different layers and then it leaves the system. That´s how I learned in school, but that is a long time ago, I guess something has changed.

But I think it is counterproductive to not use fundamental physics to explain temperature, or Outgoing Longwave Radiation. When we learned about solar radiation and the temperature of the atmosphere, our teacher used a basic model for heat. He used the surface temperature and the inverse square law. He said that the solar heat is absorbed and emitted according to the inverse square law and the difference in temperature, or heat flux, is the way to describe earth as a steam engine. That is fundamental physics and it gives the right amount of infrared radiation observed by satellites. Just use the difference and divide whats left by four.

When you say that you use a model doing it backways, in my view, and that it doesn´t use fundamental physics that describe heat, why is your way of doing it better?

One Planet Only Forever at 03:53 AM on 30 April 2017

March against madness - denial has pushed scientists out to the streets

nigelj,

To be clear, I consider the presentation in the SDGs of the changes of direction of development to be like the thoughts in the time of Roosevelt, but a far more comprehensive developed understanding.

Any aspect/system "Label" of what humans can achieve the SDGs through would be good, regardless of any legacy of bad impressions created by unethical people Winning by getting away with things in the aspect/system "Label".

Less ethical people who can get away with behaving less acceptably than others would be willing to get a competitive advantage in any game/system.

The potential good results (net-positive game results) of something like globalization achieving the SDGs needs to be presented as the counterpoint to the horrible things that people have been able to get away with. Bad things happen when too many people have a lack of awareness or better understanding, whether it is due to successful secrecy, deliberate misleading marketing, or a willful ignorance due to temptations like greed or xenophobia (racism, tribalism, nationalism). Less ethical players can and do ruin anything and everything as they pursue winning by playing in ways that can be understood to be net-negative sum game play (and they do not care because all they care about is personally perceiving themselves to be "The Winner").

vatmark at 00:43 AM on 30 April 2017

SkS Analogy 2 - Ferrari Without Gas

nigelj

"The blanket / body analogy is excellent, and will bring a wry smile to people, but I do think most people probably accept the greenhouse effect."

How do you explain the greenhouse effect with the blanket/body analogy then? Is the blanket the crust and the body is the hot interior? A blanket reduce the amount of heat absorbed by the surroundings from the hotter body, by being a poor conductor and a poor absorber. If you put something on your body increasing the amount of body heat that is absorbed, what you do is changing the surroundings of your body to suck more heat out of your body.

vatmark at 22:51 PM on 29 April 2017

SkS Analogy 2 - Ferrari Without Gas

"The concentration of greenhouse gases is like the size of a car engine: higher greenhouse gas concentration is like a bigger engine."

But greenhouse gases is the waste from the engine of a car. Or rather, the combustion product left after thermal energy is released. Making it low in internal energy and a potent absorber. First it is included in high energy hydrocarbon molecules, prone to release it´s internal energy. When energy is released it is in the opposite state, prone to absorb energy.

"Infrared radiation is like the gasoline in the tank of a car."

No, it is like the heat leaving the radiating body, cooling it. Exactly that. Infrared radiation is energy leaving the engine, the sun is like the gasoline in the tank of the car.

"Just as gasoline is the fuel that drives an engine, infrared radiation is the fuel that drives the greenhouse effect."

No, heat from the sun is the fuel that drives the engine. What you refer to as infrared radiation I suppose is the thermal emission from the surface or atmosphere. That is exactly equal to the infrared radiation leaving the cooler of the engine when water circulate in contact with a high flow of air molecules across the surface. Like wind across the earth surface.

"Global warming occurs because infrared radiation emitted from the surface of the Earth is captured by greenhouse gases in the atmosphere, increasing the temperature of the atmosphere."

But I thought greenhouse gases increased absorption, isn´t that confirmed by decreasing emission from the atmosphere? How can the atmosphere increase absorption and temperature at the same time as it decrease it´s emission?

vatmark at 22:30 PM on 29 April 2017

Humidity is falling

"Technically that means if you are calculating the radiative forcing between 280 ppmv and 400 ppmv the model would need to be set for the relative humidity at an equilibrium temperature for 280 ppmv, and retain a constant water vapour pressure when calculating the the radiative forcing outgoing IR radiation at 400 ppmv. That in turn would require knowing the offset in temperature from 1976 to the temperature equilibrium."

I don´t get it. The definition given for radiative forcing is:

"For the purposes of this report, radiative forcing is further defined as the change relative to the year 1750 and, unless otherwise noted, refers to a global and annual average value."

How is the change relative to 1750 connected to the temperature offset from 1976 to what equillibrium? What is the difference in forcing between 400ppm and what value from 1750? 280ppm? Determined how?

"I should note that there exists a technique for adjusting for stratospheric equilibrium in calculating the strict radiative forcing, which I have seen explained by David Archer."

This then has to be connected to the equillibrium of the stratosphere in 1750, am I right? We have no information about that. How is this possible as a theoretic framework for making claims about evaporation and RH in the past, today or in the future? I see no possible way to use this to claim predictive ability in climate models.

vatmark at 22:12 PM on 29 April 2017

Humidity is falling

Tom Curtis

"That is intuitive. To a first approximation, all water in the atmosphere over land comes from the ocean. Therefore the specific humidity over land will increase in line with SST, not land temperatures."

When SST increase evaporation, the SST will decrease from evaporation. If the cause of increase in SST is increasing temperature of air, evaporation is driven by increasing kinetic energy of water molecules where the energy is coming from air molecules. Which means that the kinetic and thermal energy in air molecules will drop as a result of water having a much larger heat capacity than air. Water increase less in temperature than air from the same amount of energy absorbed.

Direct evaporative cooling in open circuit is lowering the temperature and increase the humidity of air by using latent heat of evaporation, changing liquid water to water vapor. In this process, the energy in the air does not change. Warm dry air is changed to cool moist air.

This is the principle of evaporation from warmer air. It is hard to combine that with how you describe it. If water vapor increases, it would have to be connected to decreasing air temperatures in those areas where evaporation increase. And the water surface that is warming at first when evaporation increase, would also be cooling at the same time. I can only see how water vapor cools water surface temperatures and at the same time cool the air.

"While global temperatures are increasing under global warming, the models predict a slight increase in relative humidity over the ocean, with a massive reduction over land."

So when temperatures increase globally, evaporation will lower temperature of the air over the ocean. And over land, plants and water surfaces will evaporate less? And the water vapor over oceans will stay there? And not follow the usual cycle where it precipitate over land areas?

nigelj at 15:48 PM on 29 April 2017

March against madness - denial has pushed scientists out to the streets

Red Baron @10

Yes, I mean exactly as Teddy Roosevelt was saying. I agree its silly to call that socialist, and such labels are just unhelpful anway. Of course there's more to it, but you have mentioned some important things.

In fact I knew very little about TR. I live in NZ, so your comments were an eye opener for me.

I think Jospeh Stiglitz has similar views. He is not anti corporations, but just a realist that power can become excessive, and some boundaries are perfectly healthy.

I don't know how you make it stick. That's a hard question. I would say the two main political parties in my country are slowly moving towards those values by public pressure, but dragged kicking, and screaming, and not fully there yet by a long way. But there does seem to be a consensus now on at least some elements, that has stuck pretty well. Its a case of improving and broadening that consensus. It's complex.

A lot of it has to be about improving public understanding somehow. I don't have any time right now to think much about it, but will sleep on it.

A lot of the problem is lobby groups and campaign financing dependent on corporate groups, and I dont know how you change that one.

RedBaron at 12:05 PM on 29 April 2017

March against madness - denial has pushed scientists out to the streets

@9 nigelj,

AHA. You mean like this? Teddy Roosevelt

Free markets for Main Street USA, Small family run business, and even mid level business, but strict regulation against mega-corporation, trusts, and Plutocrats. As well as strong environmental and public safety regulation. Instead of a wall, we build a canal which is profitable and benefits all the Nations in the hemisphere.

That's a whole different kind of populism, and not even slightly socialist/communist either.

Yes I would say we know what to do, and even how to do it, seeing as how it was done once already.

The question is how do we make it stick? Doesn't take long for gains like that to reverse themselves.

nigelj at 11:36 AM on 29 April 2017

March against madness - denial has pushed scientists out to the streets

OPOF @8, I found the article in your link interesting and worthwhile, and it's conclusion about a possible descent into nihilism rings true, but the material in the middle is a bit confused.

I think this issue is more about cycles. America, and various other countries went through a period of "laissez faire" (extreme capitalism) in the 1800s and up until the 1930s when it all collapsed due to inherent problems with the economic model. Thats definitely not to say capitalism is bad, simply that some issues became exposed.

Then America and most western countries went through a "mixed economy" phase combining capitalism and some socialist ideas from the 1930s up until the 1980s. This period had some merit, but in turn collapsed, or stagnated for certain reasons. It was also the end of a long wave economic and investment cycle, (a type of Kondratief wave) cycle, but thats another matter that would complicate the discussion.

Then in the 1980's we had the counter reaction, and entered the era of neoliberalism and "greed is good" which was an attempt to revert to laissez faire capitalism. This ideology promotes extreme individualism, free markets, open immigration, globalisation, privatisation, deregulation, etc. This ideology has some merit in parts, but become too extreme and is the source of numerous recent problems, and it sacrifices the environment. It has generated poverty issues for some groups of people. But elements of neoliberalism like free trade and globalisation have had positive effects for many people, so its not a simple issue

The counter reaction to some elements of this globalist, neoliberal ideology has been exemplified with Donald Trump, except that he has kept some elements of the ideology such as deregulation, and ther worst forms of deregulation, for example regarding the weakining of environmental standards. But essentially Trump is trying to revert to a nationalist, more isolationist agenda, and almost a version of crony capitalism. I'm not enthused.

We need to get back to a simpler, more commonsense philosophy as Scandinavia has, of a robust capitalism and moderately free markets, but with a human touch, including appropriate restraints and controls where appropriate, (especially over environmental impacts) in other words a refined, improved version of the mixed economy ideas of the 1950s. This will enable humanity to tap the benefits of free markets and private ownership, without killing the environment or causing instability or poverty. (Imho).

Putting it another way, entrepreneurship and private enterprise is good, but "greed is not good", and a completely uncontrolled business sector is destructive to the public good.

curiousd at 07:13 AM on 29 April 2017

Humidity is falling

Thank You Tom Curtis

This shows that its good to consult with someone who has a long view knowledge of a topic before jumping to confusions over short term data.

Glad I asked.

william5331 at 06:41 AM on 29 April 2017

New study: global warming keeps on keeping on

As has been pointed out by some scientists, the amount of warming is not what we observe. It is how much the present temperature is above what we would expect based on previous interglacials in which, as soon as we reached peak warming as we came out of a glacial, we immediately started the slow slide back into a glacial. Apparently the interglacial with a most similar Milankovitch profile to our own is the one which occured some 400,000 years ago. Using this expected cooling curve as the base line, the amount of warming is more than the 1 degree we observe.

One Planet Only Forever at 06:39 AM on 29 April 2017

March against madness - denial has pushed scientists out to the streets

A related comprehensive perspective was just published:

NYtime OpEd "America, From Exceptionalism to Nihilism" by Pankaj Mishra

It mentions the damage done by the irresponsible actions of some among the elite (but the item just refers to the elite as if the whole group deserves to be smeared, proof of how damaging the actions of a few can be, how willing some people are to make any excuse to resist having to accept input or understanding that they dislike).

The OpEd also mention of a loss or disapperance of ethics. This is key. The internationally developed Sustainable Development Goals (SDGs) present a well developed basis for 'justified ethics'. The ethical basis for their development has been the basis for many previous similar presentations of developed better understanding.

In spite of that clear example of what needs to be done, what is ethically required, the SDGs lack broad popular support. The lack of popularity of such a good ethical purpose, to genuinely help to raise awareness and better understanding with the objective of improving the future for all of humanity, is the root of the problem.

Climate scientists have continued to do their part, as have the many diverse NGO and Charity groups striving to help achieve the SDGs, each facing the uphill battle of the damage done by those who care less (are care and consideration free pursuers of what they think would make them happier). The ones among the Elite who are failing humanity are typically the less ethical wealthy undeserving Winners.

Distinguishing the most-worthy, trust-worthy, among the Elite from less ethical Undeserving Winners will be difficult. Many people are unfortunately very easily impressed. The thinking of the Marque de Sade “It is infinitely better to take the side of the wicked who prosper than of the righteous who fail”, will never produce a Good Result.

Tom Curtis at 22:52 PM on 28 April 2017

Humidity is falling

Curiousd @37:

1) Quoting a single year is not very informative. Rather you should quote the trend, as in this figure from the Hadisdh dataset:

The headline result is a -0.08 (-0.18- 0.04) %/decade trend in relative humidity from 1973-2013. The negative trend is steeper in the raw data.

Two things are noteworthy about the trend. First, the trend in RH is near zero in the first part of dataset, and noticably steeper from about 1998. Over the period of the steeper trend, there was a noticable trend away from El Nino conditions towards La Nina conditions. Given that El Nino's are associated with greater global relative humidity, the trend over that period is likely significantly influenced by ENSO. The overall trend, however, is likely to be primarilly the result of global warming.

Second, as the map shows, this is a land only record, and further is restricted by latitude so as to exlcude the poles. You will notice that the graph of relative humidity provided by the NOAA 2013 state of the climate report is for land only. Further, they show a greater increase in specific humidity over ocean than over land, while the SST has increased less than the land surface temperature. That suggests the change in relative humidity over the ocean is less negative than that over land, and may even be positive. So, lacking evidence to the contrary, I would assume the that where NOAA say, "...while relative humidity—how close the air is to being completely saturated with water vapor—was far below average", they are referring to the land only data. That interpretation is supported by the immediately following sentence in the quote.

2) While global temperatures are increasing under global warming, the models predict a slight increase in relative humidity over the ocean, with a massive reduction over land. They also predict significant increases in relative humidity at the poles, particularly in the Arctic:

(Source)

That is intuitive. To a first approximation, all water in the atmosphere over land comes from the ocean. Therefore the specific humidity over land will increase in line with SST, not land temperatures. Because land temperatures are increasing faster, that will result in a reduced relative humidity over land. (Here is a recent paper exploring the mechanisms in greater detail.)

If you hold CO2 concentrations constant at an increase level, the increase in land and sea temperatures will tend to equalize at the Earth approaches the equilbrium increase in GMST. If the mechanism discussed above explains most of the change in RH, that means RH over land will restore towards its original value. That is because the ocean will get warmer relative to land as equilibrium is approached, thereby leading to an even higher specific humidity over land.

I will finish by noting that the map in the first figure above shows a very similar pattern to the changes in relative humidity shown in the second figure, over those areas which actually have data.

curiousd at 18:42 PM on 28 April 2017

Humidity is falling

Here is a quote from NASA on their 2013 "State of the Climate"

"Specific humidity—the amount of water vapor–was well above average over land and ocean in 2013, while relative humidity—how close the air is to being completely saturated with water vapor—was far below average.
Overall, water vapor in the surface atmosphere has increased over land and ocean relative to the 1970s, while the atmosphere over land is becoming less saturated".

The URL is https://www.climate.gov/news-features/understanding-climate/2013-state-climate-humidity

Rather than toss out any opinions of my own on this, because I am curious..

What are the opinions of others as to why relative humidity is decreasing, or should I not "jump to that confusion" from the NASA quote above ???

Curiousd

Moderator Response:

[JH] Link activated.

Tom Curtis at 12:07 PM on 28 April 2017

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

joe @8, it has been a little difficult getting the data on the Mendenhall Glacier tree stumps. The only public record is limited, AFAIK, to an article in the Juneau Empire, and one in Live Science. No scientific paper reporting the results has been published as yet. Cathy Connor (the lead researcher involved) did give a 2014 conference report on the glacier, buit was not on the topic of the tree stumps.

From the Juneau Empire, we learn that:

"The most recent stumps she’s dated emerging from the Mendenhall are between 1,400 and 1,200 years old. The oldest she’s tested are around 2,350 years old. She’s also dated some at around 1,870 to 2,000 years old."

Please note that they are not continuous ages. Had the area uncovered been continuously forested from 2,350 to 1,200 years ago, the older trees would have fallen and rotted due to old age, and only trees from about 1,700 to 1,200 year old would have been found. Rather, what has happened is that the area was uncovered 2,350, 1870-2,000, and 1,200 to 1,400 years ago. It was likely covered inbetween times, although there may have been intervening periods in which the glacier left the area uncovered but in which the trees remained embedded in the gravel which protected them.

The most interesting finds are tree stumps in ice caves, ie, tree stumps still technically covered by the ice, such as the example below from Live Science (chosen to provide scale):

And here is an external view from the Juneau Empire, also to show scale:

And a modern 30 year old Spruce:

Comparison of trunk width shows there is no reason to think the trees were exceptionally old at the time of their destruction. Again, this shows your idea that the area was uncovered for "... a 1,000 to 1,200 year period going back from circa 1,000 AD..." is incorrect.

Finally, here is a photo from the Juneau Empire, whose caption read:

"Vertical tree stumps remain in some of the ice caves beneath the glacier. Two ice cave stumps have been dated at two different date ranges - between 670 and 780 AD, and between 620-670 AD."

That date range is consistent with the "1,400 and 1,200 years old" date range, ie, circa 600-800 AD, mentioned in Live Science. The MWP proper did not start till circa 900 AD, so the regional warm period shown by the Mendenhall Glacier preceded the MWP by (at minimum) 100 years, and appears to have been replaced by regional cooling during the MWP.

joe - at 08:09 AM on 28 April 2017

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

But I have the same reaction to the tree stump issue. Basically so what? It's well known that during the mpw some specific locations warmed more than others. The more important point is the mwp was rather weak overall,
But anyway Tom Curtis has cast very genuine doubt about whether you can conclude the region of the Mendenhall glacier was particularly warm.

Referencing back to the tree stumps from the MWP at the mendenhall glacier, both the age of the trees and the size should cast reasonable doubt as to both the short length and breadth of the mwp in the region. Its a 1,000 to 1,200 year period going back from circa 1,000ad without the glacier. Given that time frame, Tom's geniune doubt explanation is closer to a plausible explanation.

nigelj at 05:55 AM on 28 April 2017

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

Tom Curtis @6, yes my disagreement with joe over drainage basins was pretty much terminological. In fact for practical purposes what Joe says is all fair enough, and I was being a bit pedantic.

But you are right about the need to agree on definitions. In fact I would go further and say a huge ammount of disputes and problems on the net is people talking past each other, and having different interpretations of certain words or ideas, and also general lack of clarity of writing. Of course often its a time related thing.

However what frustrated me was Joe going on about rivers returing to some drainage basin. To me it misses the point of what is going on in terms of human caused climate change, and this is what set me off!

Thank's for the detail on the antarctic. Interesting stuff.

Evan at 03:11 AM on 28 April 2017

SkS Analogy 2 - Ferrari Without Gas

Thanks Jim for this insight.

Jim Eager at 00:31 AM on 28 April 2017

SkS Analogy 2 - Ferrari Without Gas

"The proof is just how hot it got immediately after snowball earth"

A second "proof" are the cap carbonate layers that follow every snowball excusion, caused by the sudden increase in rock weathering after the land ice melts, exposing freshly ground rock to the high-CO2 atmosphere and acidic rainfall.

BaerbelW at 14:11 PM on 27 April 2017

March against madness - denial has pushed scientists out to the streets

Dcricket @5

"So what is to be done? I am perplexed. About the only idea I have is that the answer might lie in learning what makes so many people reject the consensus of those with intimate knowledge of the truth."

You may want to take a look at our MOOC "Denial101x - Making sense of climate science denial" as it has answers to your question. The current run is already in its final weeks but you can still register to check it out. All the videos from the MOOC are also available on YouTube and the list to them is here.

Hope this helps!

Tom Curtis at 11:07 AM on 27 April 2017

No climate conspiracy: NOAA temperature adjustments bring data closer to pristine

Spassapparat @34, Tony Heller (aka Steven Goddard) shows the following graph of USHCN adjustments:

You will notice that there is not a lot of scatter in the individual points from year to year, a necessary feature for the high correlation with CO2 given the very limited scatter found in the CO2 record (at least from Mauna Loa). That being said, the graph comes as a surprise to me, for I have typically seen a much larger year to year scatter in the graphs, such as shown here:

The author of this second graph is in obvious, and fundamental disagreement with Tony Heller about the size and nature of the adjustments in the USHCN temperature record. Importantly, if Heller is correct, there is a significant correlation between CO2 concentrations and temperature adjustments, but if the author of the second graph is correct, there is not. That is odd, because the author of the second graph is Tony Heller.

It turns out that when Heller is not trying to argue that there is a high correlation between CO2 concentration and temperature adjustments, he thinks the adjustments are very different from what he takes them to be when he trying to make that argument. It might make one think that Heller has adjusted his calculation of the adjustments to fit is CO2 correlation argument.

In any event, the basis of the adjustments is in fact well known. NOAA publishes the algorithms used to make the adjustments. The publish the raw and final data as well. Consequently anybody with the appropriate skills and determination can calculate the adjustments independently of NOAA. Several people have, and they have come up with the same result. Needless to say, none of NOAA's algorithms make any reference to CO2 concentration, as can be seen for the step wise adjustments as calculated by Judith Curry:

Heller knows this, so he knows that any correlation between the adjustments and CO2 concentration (whether assisted by adjusting the adjustments or not) is coincidental. His failure to discuss the known basis of the adjustments in his post must therefore be considered a calculated deceit.

Tom Curtis at 10:49 AM on 27 April 2017

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

nigelj @5, I think your dispute with Joe about the natural drainage basin is terminological rather than real. Topography can be defined by the shape of the ground, or the shape of the ground plus permanent ice. Which we use is a matter of convenience, which in turn is a matter of just how permanent the ice is on human time scales.

The perfect example to illustrate this is the Antarctic Peninsula. If you look at the level at which the ice grounds, ie, the "natural topography" according to Joe, then clearly the Peninsula is actually an island (or series of islands). Nobody, however, is making an attempt to have the Peninsula renamed, or various regions of West or East Antarctica renamed as seas. Because the ice is sufficiently permanent, we take the surface of the permanent ice sheets to define the topography of Antarctica, so any such change in nomenclature would be absurd.

The case with the Kaskawulsh glacier is interesting because the duration of the ice is significant in human terms (several hundred years) but clearly the topography defined as including the ice surface has changed significantly on a human timescale. That makes it a matter of terminological choice as to which definition is used. If we choose that the topography is taken as following the surface of the ice, then the natural drainage basin of the river has changed, just as much as if the cause of the change was the reshaping of the land by an earthquake. I am not certain, but I suspect topographical maps of the area will show contour lines following the ice surface, which would show that that was the convenction we had adopted. If we follow the convention that topology follows the land surface, then, of course, the natural drainage basin has not changed.

The key point here is that neither choice of terminology is right, or wrong. They are only convenient or inconveneint. But to avoid confusion we must be clear as to which convention we are following.

nigelj at 08:39 AM on 27 April 2017

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

Joe @3, thank's for your comment. I was indeed thinking of drainage basins in the very long term.

However I take your point, but I just think so what? I'm not sure what you think is so compelling about the river returning to a previous state / drainage basin.

The more important thing is we are melting the glacier, and altering the course of the river in that process. This could possibly cause us problems either in this specific case, or other cases, and regardless of whether it goes back to some previous state or not. It's also showing the impact of agw climate change, and is just another potential heaadache being caused by agw climate change.

Nothing personal, your comments were interesting and raised various issues. I didn't know about the tree stumps etc.

But I have the same reaction to the tree stump issue. Basically so what? It's well known that during the mpw some specific locations warmed more than others. The more important point is the mwp was rather weak overall, and climate change really "is" like a hockey stick according to all the studies I have seen.

But anyway Tom Curtis has cast very genuine doubt about whether you can conclude the region of the Mendenhall glacier was particularly warm.

nigelj at 06:41 AM on 27 April 2017

March against madness - denial has pushed scientists out to the streets

Dcrickett @5, the bible shows how these denialist issues have a pretty long history! Although I'm an athiest, I can see sense in the verses you quote.

I don't think you will remove all doubters. I saw a book a couple of years ago disputing literally all the fundamentals of Einsteins theories of relativity. I would have thought that was settled science, and the writer was a degree qualified engineer. But you can convince most doubters.

I think you have a range of sceptical views: Some people are contrarians by nature in my experience, some have genuine doubts, perhaps some have vested interests or ideological axes to grind, which leads them to deny the science. There's a range of things.

Regardless of motivations, it appears most people are prepared to change their views on various issues, if you look at history of other controversies, although it can take some time. We will never get everyone to accept climate science, but I think you can get most people to. It just takes explaining the science issues, as websites like this do. You also have to deal with worries about costs of renewable energy etc.

To some extent it's like swing voters or moderates in politics. Those are the people we need to target over climate, the moderates, and they are largely convinced by rational argument, (slowly sometimes). There will be a small group that remain very stubborn, but my instincts tell me its a small group.

Pew Research has done polls showing about 70 - 80% of people already accept the science in many countries and want action. More in some countries. So quite good progress has already been made. We tend to hear about the doubters in America, who get a lot of publicity, and think this is overwhelming or typical globally, when it isn't.

Don't get me wrong, the doubters really annoy me, but I think it's easy to let them get us down too much.

And a strong consensus like this of 70 - 80% would often lead to action by politicians on many issues. Its often enough to trigger having a referendum etc, and would certainly be enough to pass a referendum.

But unfortunately politicians do not always do what the majority want, because of their personal views, or pressure from lobby groups and people who fund their election campaigns. We see this clearly in America when you look at poll numbers.

But the larger the public consensus accepting climate science, and wanting action, the harder it is likely to be for politicians to ignore, which is why websites like this are valuable.

Spassapparat at 06:38 AM on 27 April 2017

No climate conspiracy: NOAA temperature adjustments bring data closer to pristine

Hi,

an argument that appears on many climate skeptic blogs (ex: https://stevengoddard.wordpress.com/2014/10/02/co2-drives-ncdc-data-tampering/) to justify the claim that there is deliberate tampering going on is to plot the NOAA temperature adjustments against measurements of atmospheric c02 and finding that there is an almost perfect fit. While a close correlation imo can be expected, that close of a fit appears surprising to me too. As I'm neither a climate scientist nor a statistician I was wondering whether someone could provide an explanation for this?

Dcrickett at 04:57 AM on 27 April 2017

March against madness - denial has pushed scientists out to the streets

Horrid, the denial, the disbelief.

Last Sunday the Gospel lesson was John 20:19-31, the “Doubting Thomas” story. It has some relevance. Taking the story literally, one guy of the twelve did not believe, because he didn’t see it. He could not take the word of his fellow disciples, with whom he had spent years. So, 1/12 or ≈8% on the skeptic side. He did not take the word of the two women who went to the tomb, nor of the guy who made the tomb available. So, 1/15 or ≈7%. The ≈3% disbelievers are worse then Thomas, who did not deny the evidence. These “scientists” stuck their hands in the data equivalents of the nail-holes, etc, and they still do not believe (or so they claim).

About the only tentative conclusion I can find from the above paragraph is that pointing out more nail-hole and piercèd-side data will not convince those who will themselves into disbelief.

So what is to be done? I am perplexed. About the only idea I have is that the answer might lie in learning what makes so many people reject the consensus of those with intimate knowledge of the truth.

rocketeer at 04:37 AM on 27 April 2017

2017 SkS Weekly Climate Change & Global Warming Digest #16

CO2 was about 315 ppm when the Mauna Loa observations started in 1958.

Tom Curtis at 02:16 AM on 27 April 2017

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

joe @3:

"Secondly, we know that mwp was most likely warmer in the region as indicated by the exposed tree stumps dating from the mwp ( which you acknowledge) from the retreating mendenhall glacier."

With respect, we do not know that at all. Firstly, glaciers exhibit a lagged response to temperature. Consequently, in a period of very rapid temperature rise as at present, the equilibrium glacial terminus may be significantly up slope of the observed glacial terminus. So while the tree stumps at Mendenhall Glacier give reason to think the temperature whose equilibrium terminus coincides with the current terminus, all else being equal, was less than that in the MWP in that region. But that may have been the temperature 10 or 20 years ago in a rapidly warming region.

Secondly, all else is not equal. Specifically, the glacial terminus is the result of a lagged equilibrium between precipitation on the glacier above the snow line, and temperature below the snow line. Current precipitation in the area is high, having risen from a low base (for the region) over the last century or so. That would have slowed the retreat due to temperature alone for glaciers in the region, and for some specific glaciers may have reversed it. In contrast, from approx 900 to 1300 AD, precipitation in the region fell - which would have resulted in a glacial retreat even in the absence of any increase in temperature. The reduced glacial length of Medenhall Glacier shown by the tree stumps are as likely to be a consequence of those changes in precipitation as changes in temperature. (Precipitation data from Lowe et al 1997)

Thirdly, glacial responses to temperature and precipitation changes within a region can vary significantly within a region due to shifting microclimates. Medenhall Glacier is in British Columbia, sufficiently distant from the Kaskawulsh Glacier, which is in Yukon, that the glacial record of Medenhall cannot be treated as directly relevant to Kaskawulsh. Kaskawulsh glacier has itself been shown to have advanced between the MWP and the LIA by tree ring and C14 data on woody debris, but that debris has been found next to currently existing vegetation, in some cases in trees with trunks thicker than the debris (See fig 3 of Reyes et al 2006). The debris has been carried downhill from its initial location, but it cannot be directly inferred that it originally grew uphill of the current terminus, let alone the current equilibrium terminus line.

Finally, a temperature reconstruction for the summer temperatures in South West Canada has been inferred from known glacial advances in retreats in the area (see fig 12 of Menounos et al 2008). This shows peak temperatures over the last 1000 years around 1020-60 and 1400 AD, with 1940 temperatures (20 year mean) being 0.3 C cooler than those peaks. Temperatures in the region have risen by more than 0.5 C since the 1940s:

That is, based on multiple regional proxies, it is more likely that curren temperatures are slightly warmer than the MWP peak than that they are slightly cooler; but the data is not sufficiently robust to say definitively which was warmer or cooler.

deivis_bluz at 02:14 AM on 27 April 2017

March against madness - denial has pushed scientists out to the streets

We can not use language of physics and chemistry to solve climate change. Laws of physics and chemistry produce waves which trap heat and make objects appear real. We need new laws to dissolve solid objects into light in our eyes and new words to experience our changing senses.

joe - at 23:50 PM on 26 April 2017

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

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

NigelJ - How can I say what is the river's natural drainage basin? - Its basic topography

How can I say what is the rivers natural drainage basin during the MWP? Based on known facts. First we know that the most of if not all the glaciers in the region made significant advances during the LIA (LINK)

Secondly, we know that mwp was most likely warmer in the region as indicated by the exposed tree stumps dating from the mwp ( which you acknowledge) from the retreating mendenhall glacier. You may also note that the age of the tree stumps indicate a reasonably long warm period.

I think the only meaningful definition of natural drainage basin would be "before humans substantially changed things" for example by agriculture and hydro power etc,

Are you attempting to argue that topography that has existed for millineums is not relevant to what any hydrologist would demonstrate is the natural drainage basin?

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

The mwp trees stumps that you acknowledge are just one of the many of the pieces of evidence that the region for the slim river was most likley warmer during the mwp and thus the slim river most likely drained south which is its natural drainage basin. The river most certainly followed its natural course as recently as 2k-3k years ago.

Moderator Response:

[RH] Fixed link. Please note that there is a link tool in the menu above the comment box.

Joel_Huberman at 22:52 PM on 26 April 2017

March against madness - denial has pushed scientists out to the streets

I don't agree with the 97 to 3 odds, and I think that using that argument gives too much credit to the 3 percent. Climate science is basic chemistry and physics. There is no doubt that our release of CO₂ and other greenhouse gases into the atmosphere by burning fossil fuels is warming our planet, melting glaciers, and fueling both storms and droughts. I don't understand the motivations of the 3% of doubters who claim to be climate scientists, but whatever their motivations, they're just plain wrong.

John Hartz at 13:26 PM on 26 April 2017

March against madness - denial has pushed scientists out to the streets

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