High end of climate sensitivity in new climate models seen as less plausible

PRINCETON UNIVERSITY

Research News

IMAGE
IMAGE: THE RESEARCHERS FOUND THAT MODELS WITH LOWER CLIMATE SENSITIVITY ARE MORE CONSISTENT WITH OBSERVED TEMPERATURE DIFFERENCES, PARTICULARLY BETWEEN THE NORTHERN AND SOUTHERN HEMISPHERES. THE GRAPH SHOWS CHANGES IN THE ANNUAL… view more CREDIT: IMAGE BY CHENGGONG WANG, PROGRAM IN ATMOSPHERIC AND OCEANIC SCIENCES, PRINCETON UNIVERSITY

A recent analysis of the latest generation of climate models — known as a CMIP6 — provides a cautionary tale on interpreting climate simulations as scientists develop more sensitive and sophisticated projections of how the Earth will respond to increasing levels of carbon dioxide in the atmosphere.

Researchers at Princeton University and the University of Miami reported that newer models with a high “climate sensitivity” — meaning they predict much greater global warming from the same levels of atmospheric carbon dioxide as other models — do not provide a plausible scenario of Earth’s future climate.

Those models overstate the global cooling effect that arises from interactions between clouds and aerosols and project that clouds will moderate greenhouse gas-induced warming — particularly in the northern hemisphere — much more than climate records show actually happens, the researchers reported in the journal Geophysical Research Letters.

Instead, the researchers found that models with lower climate sensitivity are more consistent with observed differences in temperature between the northern and southern hemispheres, and, thus, are more accurate depictions of projected climate change than the newer models. The study was supported by the Carbon Mitigation Initiative (CMI) based in Princeton’s High Meadows Environmental Institute (HMEI).

These findings are potentially significant when it comes to climate-change policy, explained co-author Gabriel Vecchi, a Princeton professor of geosciences and the High Meadows Environmental Institute and principal investigator in CMI. Because models with higher climate sensitivity forecast greater warming from greenhouse gas emissions, they also project more dire — and imminent — consequences such as more extreme sea-level rise and heat waves.

The high climate-sensitivity models forecast an increase in global average temperature from 2 to 6 degrees Celsius under current carbon dioxide levels. The current scientific consensus is that the increase must be kept under 2 degrees to avoid catastrophic effects. The 2016 Paris Agreement sets the threshold to 1.5 degrees Celsius.

“A higher climate sensitivity would obviously necessitate much more aggressive carbon mitigation,” Vecchi said. “Society would need to reduce carbon emissions much more rapidly to meet the goals of the Paris Agreement and keep global warming below 2 degrees Celsius. Reducing the uncertainty in climate sensitivity helps us make a more reliable and accurate strategy to deal with climate change.”

The researchers found that both the high and low climate-sensitivity models match global temperatures observed during the 20th century. The higher-sensitivity models, however, include a stronger cooling effect from aerosol-cloud interaction that offsets the greater warming due to greenhouse gases. Moreover, the models have aerosol emissions occurring primarily in the northern hemisphere, which is not consistent with observations.

“Our results remind us that we should be cautious about a model result, even if the models accurately represent past global warming,” said first author Chenggong Wang, a Ph.D. candidate in Princeton’s Program in Atmospheric and Oceanic Sciences. “We show that the global average hides important details about the patterns of temperature change.”

In addition to the main findings, the study helps shed light on how clouds can moderate warming both in models and the real world at large and small scales.

“Clouds can amplify global warming and may cause warming to accelerate rapidly during the next century,” said co-author Wenchang Yang, an associate research scholar in geosciences at Princeton. “In short, improving our understanding and ability to correctly simulate clouds is really the key to more reliable predictions of the future.”

Scientists at Princeton and other institutions have recently turned their focus to the effect that clouds have on climate change. Related research includes two papers by Amilcare Porporato, Princeton’s Thomas J. Wu ’94 Professor of Civil and Environmental Engineering and the High Meadows Environmental Institute and a member of the CMI leadership team, that reported on the future effect of heat-induced clouds on solar power and how climate models underestimate the cooling effect of the daily cloud cycle.

“Understanding how clouds modulate climate change is at the forefront of climate research,” said co-author Brian Soden, a professor of atmospheric sciences at the University of Miami. “It is encouraging that, as this study shows, there are still many treasures we can exploit from historical climate observations that help refine the interpretations we get from global mean-temperature change.”

###

The paper, “Compensation Between Cloud Feedback and Aerosol?Cloud Interaction in CMIP6 Models,” was published in the Feb. 28 edition of Geophysical Research Letters. The research was supported by the National Oceanic and Atmospheric Administration (grants NA20OAR4310393 and NA18OAR4310418) and the Carbon Mitigation Initiative based in Princeton University’s High Meadows Environmental Institute (HMEI).

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Steve Case
March 3, 2021 6:16 pm

In other words, “Not as bad as previously thought” I’ll just stick my neck out and predict that this won’t be covered by the so-called mainstream press.

Dave Fair
Reply to  Steve Case
March 3, 2021 6:37 pm

Any predictions on the UN IPCC AR6 actually mentioning the subject? How about their qualifying the CMIP6 model results in light of these obvious problems? How about their acknowledging RCP 8.5 is physically impossible?

Roger Knights
Reply to  Dave Fair
March 3, 2021 9:04 pm

AFAIK, the ICPP sets a deadline on the papers it considers, and this paper is too late to be considered.

Redge
Reply to  Roger Knights
March 3, 2021 11:38 pm

That would depend if the paper supports the narrative or not

IIRC, the IPCC accepted papers after the deadline to support AR4

RickWill
Reply to  Dave Fair
March 3, 2021 9:30 pm

RCP 8.5 no longer exists. It is now the much more woke SSP5.

stinkerp
Reply to  Steve Case
March 4, 2021 4:38 am

Anyone who takes a few minutes to compare measured temperature and sea level trends to model projections will discover that we are on track for the lowest, mildest scenario, RCP2.6.

That’s the scenario based on the unrealistic notion of drastic reduction of CO2 emissions by every country on earth starting right now. In fact many Western countries are modestly reducing emissions but those reductions are dwarfed by increasing emissions from China, India, and the rest of the developing world. The U.S. has reduced emissions the most, not through legislation, “carbon taxes”, “cap-and-trade” or other ridiculous schemes but by widespread voluntary adoption of energy efficiency (which generally saves consumers money) and improved utility scale power generation technologies.

Despite globally increasing CO2 emissions, measurements show we are in the RCP2.6 range of warming and sea level rise. The lesson? Climate models are wildly wrong and so are climate alarmists.

Last edited 2 months ago by stinkerp
Gerry
Reply to  Steve Case
March 11, 2021 3:07 pm

“Climate Change Not as bad as previously thought” gets 535,000,000 hits on Google
“Climate Change worse than previously thought” gets 86,300,000 hits on Google
Winning!!!!
Suggests that Princeton’s reference to an oxymoronic ‘… current scientific consensus’ is more a putsch push than consensus

Dave Fair
March 3, 2021 6:33 pm

Son of a gun! High sensitivity models fudge historical aerosols to better track average global temperatures. Whoda thunk? [Well, everybody with any integrity over the past 20 years.]

The ‘science’ is not settled and is inadequate for policy making purposes.

Robert of Texas
March 3, 2021 6:45 pm

Not to fear…They are adjusting the old data as we speak so that it better matches up with a higher sensitivity to CO2. If you can’t make the model work, just change the past data.

Steve Reddish
March 3, 2021 6:49 pm

“Clouds can amplify global warming and may cause warming to accelerate rapidly during the next century,”
I’d like to see the evidence that supports this claim!

DMacKenzie
Reply to  Steve Reddish
March 3, 2021 11:27 pm

An extra square meter of cloud cover reflects about 600 watts back to outer space. Or else, heat from the sun on the water surface causes more water vapor in the atmosphere, which in turn causes more clouds. Balance between sunshine on the ocean and clouds refectong sunshine back to outer space is what controls the planet’s temperature. Anyone who believes clouds amplify global warming is simply wrong, at least when the Sun is shining….

DMacKenzie
Reply to  DMacKenzie
March 4, 2021 6:32 am

….clouds reflecting sunshine…note to self, turn spell checker ON…

DMacKenzie
Reply to  DMacKenzie
March 4, 2021 8:37 am

It is also worth realizing, that as the ocean surface warms, and more water vapor is forced into the air, there IS an increase in local IR from those additional water molecules. This is the water vapor amplification that always comes up in CO2 forcing calculations. However, as soon as the water vapor saturation curve is crossed, clouds formed at say approx 1000 meter elevation start reflecting hundreds of watts per square meter, offsetting the paltry few watts of CO2 surface forcing. We actually know quite a bit about cloud formation, read up on Skew-T diagrams in US, Tephigrams elsewhere. We also know quite a bit about evaporation rates from bodies of water, search Penman equation for starters. Climate scientists steadfastly refuse to put 2 and 2 together, possibly because the control is so strong but randomly delayed, that it doesn’t even look like feedback…..

DMacKenzie
Reply to  DMacKenzie
March 4, 2021 9:09 am

….and that’s because two parameters that offset each other will appear to the viewer to have no effect on the phenomenon. For example the northern and southern Hemispheres have 40% different ocean surfaces, yet CERES shows only 2% difference in radiated heat. That does NOT warrant coming to the conclusion that Albedo makes no difference, but does warrant looking at high Albedo cloud cover over the larger SH ocean area being an important factor.

Steve Reddish
March 3, 2021 6:59 pm

“A higher climate sensitivity would obviously necessitate much more aggressive carbon mitigation,”
And:
“the models have aerosol emissions occurring primarily in the northern hemisphere, which is not consistent with observations.”
They admit that invalid models cause hyperventilation…er…hypermitigation of “carbon”, and observe that current models are invalid.

Chris Hanley
March 3, 2021 6:59 pm

“… Because models with higher climate sensitivity forecast greater warming from greenhouse gas emissions, they also project more dire — and imminent — consequences …”.
I recall a commenter here adamantly claiming climate sensitivity was a product of climate models, not an input.

RickWill
Reply to  Chris Hanley
March 3, 2021 9:36 pm

When they fiddle 20 to 30 input parameters to arrive at a single number, he is strictly correct.

The models are correct when they fiddle a million or more temperature records to get what the models produce.

Australia is really lagging here. The BoM are only up to ACORN2. I saw today that the UK are up to HadCRUT 7. I wonder when Joe Average begins to realise that are being taken for a ride into fantasy.

Dave Fair
Reply to  Chris Hanley
March 3, 2021 11:44 pm

UN IPCC climate modelers have been known to state that they adjust parameters until they get “an ECS that looks about right.” The only period for which the various models’ outputs even approximate each other is over the “tuning period” during the late 20th Century. Otherwise, their earlier ‘hindcasts’ and future ‘projections’ vary wildly from one to the other.

Additionally, the base average global temperatures of the various models vary by about 3 C; they are collectively not modeling the same Earth. When they say “its the physics” they can’t be correct because, for example, evaporation over the oceans is different at 15 C than at 12 C.

Tim Gorman
March 3, 2021 7:02 pm

Clouds can amplify global warming”

Do these yahoo’s *ever* go outside? Perhaps to stand in direct sun and then in shade from clouds?

commieBob
Reply to  Tim Gorman
March 3, 2021 7:53 pm

Clouds may be the real bear.

Clouds reflect the sun’s rays away and shield the surface, thereby reducing warming.

On the other hand …

At night clouds shield the surface from the cold of outer space. A cloudless night on the desert is darn cold. Clouds are like a warm comfy blanket.

On the other, other hand …

The whole CAGW thing is based on positive feedback. CO2 warms the planet a little bit which evaporates some water and water is the main greenhouse gas so the planet warms even more according to ‘their’ theory.

‘They’ have produced data that shows that evaporation is indeed increased. The problem (for ‘them’) is that evaporated water often turns into clouds which reflect the sun’s rays away and shield the surface of the planet.

Not only that but, humid air is less dense and therefore increases convection, thus removing heat from the surface more quickly.

It’s pretty clear that, at the equator, clouds are a large net negative feedback. Evaporation and the formation of clouds is sufficiently rapid that there are thunder storms nearly every day.

As far as I can tell, most people agree that clouds are the one thing climate models don’t handle well.

Joni Mitchell nailed it.

Last edited 2 months ago by commieBob
Alexy Scherbakoff
Reply to  commieBob
March 3, 2021 8:03 pm

I haven’t come across increased evaporation, increased humidity or increased clouds.

RickWill
Reply to  Alexy Scherbakoff
March 3, 2021 9:55 pm

It goes up and down about 5mm per year. I have not seen any trend apart from climate models.

The CMIP5 model average pme goes negative if integrated over any 3 years.

Alexy Scherbakoff
Reply to  RickWill
March 3, 2021 11:03 pm

We need to coin a new phrase. Temporary Regional Climate Change.

Tombstone Gabby
Reply to  Alexy Scherbakoff
March 4, 2021 12:46 pm

A new ‘phrase’ – how ’bout a single word: “weather”?

RickWill
Reply to  commieBob
March 3, 2021 9:44 pm

As far as I can tell, most people agree that clouds are the one thing climate models don’t handle well.

Where are these “most people”. Anyone who cannot see that climate models are conceptually flawed is ignorant of them or living in a fantasy world. They simply correlate CO2 to temperature rise with an inertial lag.

The surface energy balance on Earth is set by two temperature controlled processes achieving -2C at water/sea-ice interface and 30C in tropical ocean warm pools. The rest is just noise. CO2 plays zero role.

commieBob
Reply to  RickWill
March 4, 2021 5:12 am

As far as I can tell, most alarmist climate scientists will admit that the models don’t handle clouds very well.

What are the main unknowns about climate?The effect of clouds, specially cloud radiative feedback. Some clouds have a cooling effect, others a warming effect. As the world warms, evaporation of ocean waters will occur, and that will bring more clouds — that’s where clouds come from. Low clouds tend to have a cooling effect and counteract warming due to the greenhouse effect. These are the clouds that make you shiver at the beach. Very high clouds do the opposite — no shade, and a net warming effect. There is no consensus on which type of cloud will win out over the other. Another is the role of aerosols. These are tiny particles, not gases, in the atmosphere that on average cool the planet. But by how much is very uncertain. Both of these are critically important to understand how the earth will respond to greenhouse warming.

John C. Mutter

As you point out, skeptics would say the models don’t handle anything very well either. So everyone agrees the models don’t handle clouds very well. We should all get together and sing Kumbaya. 🙂

MarkW
Reply to  commieBob
March 4, 2021 8:05 am

Once you admit that models don’t handle clouds well, you have admitted that models aren’t capable of predicting climate.

John Tillman
Reply to  commieBob
March 4, 2021 8:18 am

The GCMs don’t really handle clouds at all. The models just parameterize them, so that their effect can be whatever the computer gamers want. Nor do the models deal with evaporative cooling.

In order actually to program clouds, computing power will have to increase a billion times or more.

Tim Gorman
Reply to  John Tillman
March 4, 2021 10:30 am

OR! They can downsize what they are trying to predict. Instead of doing global do something small enough that clouds can actually be handled as basic physics. Something like the central states of the US. Or Australia. Or maybe just look at California and Texas and include the basic physics for evaporate cooling. At some point the computers will be able to handle this.

Alexy Scherbakoff
March 3, 2021 7:33 pm

Climate sensitivity is a notion and not a fact.

fred250
March 3, 2021 7:51 pm

Trouble with GISS Temp is that it is totally meaningless before about 1979.

And highly dubious after that because of the manic adjustment of past data that they do actually have.

They have BASICALLY NO DATA before 1979 for nearly all the Southern Hemisphere, which is mainly oceans

Even the non-famous Phil Jones stated as such.

Data they do have shows Australia WARMER than now around 1880 – 1920

comment image

And shows South Africa warmer than now in the 1940s.

comment image

How they end up with the charts they do, shows a HIGHLY DUBIOUS process.

Last edited 2 months ago by fred250
fred250
March 3, 2021 7:55 pm

They KNOW that there is a COOLING TREND COMING

We will see more and more….

…. “not as bad as we thought, except in the long term where it will be far worse”

…. type of articles over the coming years as the sullen sun starts to bite.

Dave Fair
Reply to  fred250
March 3, 2021 11:52 pm

The UN IPCC AR5 had to arbitrarily reduce the medium-term model ‘projections’ because the world is not warming as the modelers’ predicted. Of course, they left the long-term model ‘projections’ in place, ignoring clear bias.

Nick Graves
Reply to  fred250
March 4, 2021 12:44 am

That’ll ‘prove’ that the glorious measures they’ve taken are actually working.

So we’ll need to do more, just in case AGW restarts.

7CHIMPS will ‘prove’ the tipping point is lower than we thought…

March 3, 2021 7:58 pm

So, the effort to ‘excuse’ Ridiculous CMIP6 begins?
See essay Cloudy Clouds in ebook Blowing Medicine a long time ago now.

Juan Slayton
Reply to  Rud Istvan
March 4, 2021 4:53 am

Blowing Smoke?
: > )

March 3, 2021 8:04 pm

[[Researchers at Princeton University and the University of Miami reported that newer models with a high “climate sensitivity” — meaning they predict much greater global warming from the same levels of atmospheric carbon dioxide as other models — do not provide a plausible scenario of Earth’s future climate.]]

Duh, the best computer climate modelos are those with a climate sensitivity of ZERO. The Sun’s 5500C photons alone heat the Earth, and CO2’s weak puny -80C photons do nothing. How sad that even Princeton U. falls for the CO2 global warming hoax, even when the evidence is right in front of their eyes.

https://www.quora.com/What-happens-to-the-Suns-radiation-when-it-gets-the-Earth-s-atmosphere/answer/TL-Winslow

John Pickens
March 3, 2021 8:26 pm

TL,DR: Hindcasting doesn’t work.

fred250
Reply to  John Pickens
March 3, 2021 9:04 pm

Hindcasting doesn’t work.”

.

ESPECIALLY when the past data has been highly corrupted and mal-adjusted.

If hind-casting does happen to match past data, the model will have a substantial unrealistic warming trend BUILT-IN !

Weekly_rise
Reply to  John Pickens
March 4, 2021 8:08 am

More accurately, using the simulation of historic global mean surface temperature as a primary metric of model skill might yield misleading results. Differences in spatial patterns are important.

tmatsi
March 3, 2021 8:34 pm

97% of Climate astrologers have made up their minds, please do not confuse them with facts!!

Clyde Spencer
March 3, 2021 8:35 pm

The researchers found that both the high and low climate-sensitivity models match global temperatures observed during the 20th century.

Of course the models match the 20th century because the models are explicitly tuned to match history!!! I get the impression that these ‘researchers’ don’t understand that the way the “physics-based” models get even somewhat realistic results is by using fudge factors and subjective parameterizations to fit them to the past. There is, however, no reason to believe that they will continue to track temperatures once they are no longer constrained by known temperatures.

RickWill
Reply to  Clyde Spencer
March 3, 2021 9:59 pm

The “known” temperature right now covers a 2C range according to 9 CMIP6 models.

CMIP6_Compare.png
BobM
March 3, 2021 9:21 pm

What does this mean? The science is not really settled? I mean, really? Come on, you’re joking, right?

“and how climate models underestimate the cooling effect of the daily cloud cycle.”
So the climate models don’t have this working properly yet? That the daily cloud cycle provides a cooling effect is a surprise? Like Willis has shown so many times already? That part seems like it should be settled science, no? These guys are just finding out what we all know?

“Understanding how clouds modulate climate change” Clouds modulate weather, as in “the daily cloud cycle”…

But it is good to see another walk-back.

RickWill
March 3, 2021 9:29 pm

Just take the Chinese FGOALS model as gospel and no policy decisions are required; yet. Run out of coal long before there is a Climate Change issue.

Or just accept that none of them are worth more than 5 seconds of consideration as the utter tripe they are and move on to things that actually matter.

Actually if China does not find new suppliers for coal, it will run out by the end of the century; taking its own reserves to zero and current suppliers to scrapping.

US already has the largest proven coal reserves of any nation so, lucky for China, they have a bought and paid for POTUS they can rely on to ramp up shipments. Come on man, get on with it! It will be wonderful to watch.

CMIP6_Compare.png
Joel O'Bryan
March 3, 2021 10:11 pm

After AR5 went forth in 2014 with the stupid RCP 8.5 CMIP5 scenario, it took several years for the climatists to admit it was really not BAU, but actually quite unrealistic. But RCP 8.5 has served its intended cynical purpose, which was to fuel a cottage industry of rentseekers using it to find alarmist results to publish in their disclipline.
Same now with the unrealistic high-end scenarios in the coming AR6. They are meant to fuel an ability of other disciplines to find impact in unrelaitic scenarios before they are outed.

Law of Nature
Reply to  Joel O'Bryan
March 4, 2021 7:17 am

You are absolutely correct! And this is where the scientists in this article fail. They identified some unlikely/unscientific behavior of some models, the next step should be to “fight like hell” that these models do not become the base of any policy.. but that never happens, at least it did not happen in the past and why should it? Everybody wins, the scientists spoke out and cover their science “we told you it´s a little bit high!” and the policy makers can still use the models to make their policies (which they don´t really care about, it´s all about fearmongering)

Sweet Old Bob
Reply to  Joel O'Bryan
March 4, 2021 8:44 am

Correct.

“Clouds can amplify global warming and may cause warming to accelerate rapidly during the next century,” said co-author Wenchang Yang . ”

Stupid on Meth ….

Peter Wilson
March 3, 2021 11:57 pm

“Our results remind us that we should be cautious about a model result, even if the models accurately represent past global warming,”

Duh!

Jim Clarke
Reply to  Peter Wilson
March 5, 2021 10:11 am

What ‘past global warming’ do they accurately represent? Accurately representing only 3 decades of a past that is 600 million years long, is called curve fitting, not ‘accurate representation’! They had to manipulate the historical data to expand their ‘accuracy’ beyond 3 decades of coincidence to a hundred years of misrepresentation they call ‘skill’, but even their lies fall way short of supporting their theory and the contention of a climate crisis. For anyone not being paid to believe that CO2 is the primary driver of climate, it is obvious that natural climate variability dwarfs the effect of changing CO2, and is driven by the natural ocean/atmospheric cycles. The global cooling over the next 30 years will destroy the climate crisis narrative and they know it. That is why they are insanely trying to get all the money and power out of the warming narrative while they can.

March 4, 2021 12:36 am

Instead, the researchers found that models with lower climate sensitivity are more consistent with observed differences in temperature between the northern and southern hemispheres ..

It’s all about heat piracy near the Caribbean, stealing heat from south to north (to counterbalance the AMOC which, like father Christmas, really does exist!!)

Widespread signals of Southern Hemisphere ocean cooling (and AMOC heat piracy) – Odyssey (wordpress.com)

Newminster
March 4, 2021 1:37 am

“… the study helps shed light on how clouds can moderate warming … in models”

Eh?

Gary Ashe
March 4, 2021 2:56 am

More climastrology from gold plated institutions how can it possibly be wrong.
The cream of todays post normal science.
Only it is wrong cos any body who lives in the real world knows it is gradually getting colder, this winter my central heating has been on full chat, but maybe its just my lying eyes and frozen arse kidding me and i should just stick with the gold plated turds, er i mean institutions.

March 4, 2021 3:49 am

When you are stuck in a hole, stop digging.

Mike Maguire
March 4, 2021 4:51 am

The less extreme the warming is on the real planet, the more the warming must be on the simulated planet…….to scare people into taking action.

Mike Maguire
Reply to  Mike Maguire
March 4, 2021 4:18 pm
Anon
March 4, 2021 5:11 am

Someone is “off script” here. By now everyone should recognize that these outputs are meant to serve as “guidelines” for the measurement groups so as they will “adjust” accordingly and proportionally.

Very much like annual “sales quotas” at a used car lot… and they are supposed to increase exponentially, that is a feature, not a flaw. Impossibly high quotas ensures that the cream rises to the top and weeds out the under-performers who can’t handle the pressure (i.e. the heat, in this case).

No doubt the current guys are getting a bit “long in the tooth” and are sitting on their laurels, so management has to cultivate the next generation.

Greg
March 4, 2021 5:12 am

“The 2016 Paris Agreement sets the threshold to 1.5 degrees Celsius.”

No it does not! It says it would be really nice to keep it “much lower” than 2 deg C. It does not change the fictitious “threshold” which itself was pulled out of the air ( to put it politely ).

John Garrett
March 4, 2021 6:10 am

Who wrote the text of this post?

Which part(s)— if any— were part of the Princeton press release?

Which part(s)— if any— were written by Charles Rotter?

Rudi
March 4, 2021 6:38 am

Why did earth not get stuck in a hot house scenario when CO2 was 2000 ppm ?
Answer: There are many negative feedback mechanism, most of them probably due to the fact that earth is covered to 73% by water. It is time for the climate gamers to install that into their toy models.

S.K.
March 4, 2021 7:15 am

Researchers at Princeton University and the University of Miami reported that newer models with a high “climate sensitivity” — meaning they predict much greater global warming from the same levels of atmospheric carbon dioxide as other models — do not provide a plausible scenario of Earth’s future climate.

The above statement is the only segment I agree with. The remainder is propaganda.

Weekly_rise
March 4, 2021 8:12 am

This is an interesting paper that I’m still trying to unpack, but we should be careful in the implications being drawn from it. The results of this study indicate that the highest-sensitivity models are not capturing observed historic spatial patterns in cloud response, but it does not mean that climate sensitivity is low. I think it’s been known for a while that the highest CMIP6 estimates are almost certainly too high, this paper just sheds some light on why.

Gary Ashe
Reply to  Weekly_rise
March 4, 2021 10:28 am

For anyone wondering where this latest troll spung forth from.

https://www.reddit.com/user/Weekly_Rise/

”Theres no established connection between the strength of the solar cycle and global temperature trends”

And if that isn’t weapons grade trolling i don’t now what is.

Last edited 2 months ago by Gary Ashe
Steve Z
March 4, 2021 11:27 am

[QUOTE]Researchers at Princeton University and the University of Miami reported that newer models with a high “climate sensitivity” — meaning they predict much greater global warming from the same levels of atmospheric carbon dioxide as other models — do not provide a plausible scenario of Earth’s future climate.

Those models overstate the global cooling effect that arises from interactions between clouds and aerosols and project that clouds will moderate greenhouse gas-induced warming — particularly in the northern hemisphere — much more than climate records show actually happens, the researchers reported in the journal Geophysical Research Letters. [END QUOTE]

Why would models that “overstate the global cooling effect” due to clouds result in higher predicted temperatures? Wouldn’t they result in lower predicted temperatures?

Of course, the whole idea of a “climate sensitivity” to CO2, with a supposedly fixed temperature increase for every doubling of CO2 concentration, is not based in physical reality, but on a faulty equation proposed in 1906 by Svante Arrhenius, which the IPCC never bothered to revise or replace by an equation based on the physics of IR absorption by gases.

I wrote about this in detail in a previous post a few days ago, but in summary, the total warming due to CO2 in clear weather would follow a relationship of the form

dT(z) = K* Io [1 – exp(-ACz)]

where
dT (z) = temperature rise as a function of altitude
Io = IR radiation intensity from Earth’s surface, a function of temperature and wavelength
A = IR absorption coefficient, a function of wavelength
C = CO2 concentration
z = altitude above Earth’s surface

The constant K would have to be evaluated by integrating over all IR wavelengths. This equation is based on Beer’s law for IR absorption by gases.

First of all, the total possible warming due to CO2 is limited to K * Io, which is the limit of the function as C goes to infinity. This illustrates the saturation effect–if the CO2 concentration is high enough, all the available energy is absorbed, and further increases have no further warming effect, they only concentrate the warming at a lower altitude.

The net effect of a doubling of CO2 would also vary by wavelength and altitude. Suppose that, at a given wavelength at current CO2 concentrations, ACz = 2.0, which means that the current warming due to CO2 would be 0.8647 K*Io. If C is doubled, ACz becomes 4.0, in which case the total warming due to CO2 would be 0.9817 K*Io, so that doubling the CO2 concentration increases the temperature by 0.1170 K*Io. If the CO2 concentration is doubled again, ACz = 8.0, and the total warming becomes 0.9997 K*Io, so the second doubling produces a net increase of 0.0180 K*Io, or about 6.5 times less warming than the first doubling.

This shows that “climate sensitivity” to a doubling of CO2 concentration is NOT a constant, but it decreases sharply as CO2 concentrations increase. A third doubling would cause an increase of less than 0.0003 K*Io, which would be negligible.

Tom Abbott
Reply to  Steve Z
March 5, 2021 9:04 am

“Why would models that “overstate the global cooling effect” due to clouds result in higher predicted temperatures?”

I noticed that, too, while reading the article.

I think the author meant to say “understate” rather than “overstate”.

Richard M
March 4, 2021 3:19 pm

Here’s an idea for a model. If you perform a simple mathematical transformation on GHG radiation in the Earth’s energy domain (atmosphere + surface) you get a rather interesting result. The transformation is: change every event (emission + reabsorption) to an average one. When you do this the overall energy flow should be identical. Each photon that leaves the surface will stop N times as it is reabsorbed. Each photon will travel a distance of X meters towards space before being reabsorbed. It will take T seconds for each event to complete.

Notice this transformed system has no downwelling IR. Yet, it is mathematically equivalent to our current atmosphere. So much for the greenhouse effect. Now, what will happen if you add more GHGs to the energy domain? Since GHGs already absorb all the radiation coming up from the surface that it can absorb, the most it can do on the absorption side is slow the process down slightly. N would get larger, X would get shorter and T a little longer. However, you are also adding more emitters which naturally has the opposite effect. The two would likely cancel out. The only way to warm the system is to add more energy to it.

Can anyone tell me why this isn’t a valid transformation? I think this is telling us something important.

Oddgeir
March 14, 2021 9:41 am

You are proving the models failed?

Why would you accept “NASA’s Goddard Institute for Space Studies Surface Temperature Analysis project” data to be true?

We’re having failed models AND fake data here. None of the lines are anywhere correct, neither the red-, the blue- nor the black line.

Oddgeir

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