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Breaking the hegemony of global climate models – Watts Up With That?



Reposted from Dr. Judith Curry’s Climate Etc.

Posted onOctober 6, 2021bycurryja|

by Judith Curry

A rather astonishing conclusion drawn from reading the fine print of the IPCC AR6 WG1 Report.

Well, Ive been reading the fine print of the IPCC AR6 WG1 Report. The authors are to be congratulated for preparing a document that is vastly more intellectually sophisticated than its recent predecessors. Topics like deep uncertainty, model fitness-for-purpose (common topics at Climate Etc.) actually get significant mention in the AR6. Further, natural internal variability receives a lot of attention, volcanoes a fair amount of attention (solar not so much).

If we harken back to the IPCC AR4 (2007), global climate models ruled, as exemplified by this quote:

There is considerable confidence that climate models provide credible quantitative estimates of future climate change, particularly at continental scales and above.

The IPCC AR4 determined its likely range of climate sensitivity values almost exclusively from climate model simulations. And its 21st century projections were determined directly from climate model simulations driven solely by emissions scenarios.

Some hints of concern about what the global climate models are producing were provided in the AR5. With regards to climate sensitivity, the AR5 included this statement in a footnote to the SPM:

No best estimate for equilibrium climate sensitivity can now be given because of a lack of agreement on values across assessed lines of evidence and studies.

More specifically, observationally-based estimates of ECS were substantially lower than the climate model values.

Perhaps more significantly, figure 11.25 in the AR5 included a subjective red-hatched area determined from expert judgment that the climate models were running too hot. It is noted that the projections beyond 2035 were not similarly adjusted.

IPCC AR6 global warming

The IPCC AR6 takes what was begun in the AR5 much further.

With regards to equilibrium climate sensitivity, the AR6 breaks with the long-standing range of 1.5-4.5C and narrows the likely range to 2.5-4.0 C. Here is how that range compares with previous estimates and also the CMIP6 models (as analyzed by Mark Zelinka):

The AR6 analysis of ECS was influenced heavily by Sherwood et al. (2020). I agree with dropping the top value down from 4.5 to 4.0C. However, I do not agree with their rationale for raising the lower value from 1.5 to 2.5C. Without going into detail on my concerns here, I note that Nic Lewis is working on an analysis of this. But the main significance of AR6s narrower range is the lack of influence of the CMIP6 ECS values.

A substantial number of the CMIP6 models are running way too hot, which has been noted in many publications. In its projections of 21st century global mean surface temperatures, the AR6 provides constrained projections (including climate models with reasonable values of climate sensitivity that reasonably simulate the 20th century). Figure 4.11 from the AR6 shows the magnitude of the constraints. For SSP5-8.5, the magnitude of the constrained relative to the unconstrained CMI6 is 20%.

For the first time, CMIP6 includes actual scenarios of volcanic activity and solar variability.  CMIP6 includes a background level of volcanic activity (no major eruptions) and an actual projection of 21st century solar variability from Matthes (2017) (discussed previously here), although few models are up to the task of credibly handling solar indirect effects.  The AR6 only considers these baseline solar and volcano scenarios; the other volcanic scenarios (shown in Figure 1, Box 4.1 of the AR6) and the Maunder minimum scenario from Matthes (2017) are surely more plausible than SSP5-8.5 and hence should have been included in the projections.

The AR6 also acknowledges the importance of natural internal variability, in many of the Chapters.  CMIP6 included Single Model Initial Condition Large Ensembles (SMILEs; section 6.1.3).  However, there are substantial disparities between the large-scale circulation variability in observations versus most models (IPCC AR6 Chapter 3) decadal variability that is too strong and multi-decadal and centennial variability that is too weak. A few of the models seem to do a pretty good job, notably GFDL.

Here are the ensemble forecasts for SSP2-4.5, including the projections from the individual models, the constrained versus unconstrained 90% range, and the AR6 best estimate (note this image was pulled from a CarbonBrief article). The AR6 best estimate is near the lower end of the entire range; this bias doesnt allow much scope for natural variability (particularly of the multi-decadal variety) at the lower end of the model range to truly illustrate a realistic time range as to when we might pass the 1.5 and 2C danger thresholds.

To minimize some of the problems related to constraining the projections, there is an emphasis on assessing impacts at different levels of global warming, e.g. 2, 4 degrees C.

Regional projections

The IPCC AR6 report provides a substantial emphasis on regional climate change (Chapters 10, 12). The focus is on a distillation of diverse sources of information and multiple lines of evidence, and indirectly acknowledges that global climate models arent of much use for regional projections.

Climate emulators

Since the Special Report on 1.5 degrees, the IPCC has increasingly emphasized the use of climate emulators, which are highly simplified climate models (see this CarbonBrief article for an explainer) that are tuned to the results of the global general circulation model based Earth System Models. These models are very convenient for policy analysis, enabling pretty much anyone to run many different scenarios.

And theres no reason why this general framework couldnt be expanded to include future scenarios of warming/cooling related to volcanoes and solar, and also multi-decadal internal variability. This framework could be very useful for regional climate projections.

However, climate emulators are not physics-based models.

Are global climate models the best tools?

Text from an essay I am writing:

In the 1990s, the perceived policy urgency required a quick confirmation of dangerous human-caused climate change. GCMs were invested with this authority by policy makers desiring a technocratic basis for their proposed policies.  Shackley et al.  However, both the scientific and policy challenges of climate change are much more complex than was envisioned in the 1990s. The end result is that the climate modeling enterprise has attempted a broad range of applications driven by needs of policy makers, using models that are not fit for purpose.

Complex computer simulations have come to dominate the field of climate science and its related fields, at the expense of utilizing traditional knowledge sources of theoretical analysis and challenging theory with observations. In an article aptly titled The perils of computing too much and thinking too little, LINK atmospheric scientist Kerry Emanuel raised the concern that inattention to theory is producing climate researchers who use these vast resources ineffectively, and that the opportunity for true breakthroughs in understanding and prediction is being diminished.

Complexity of model representation has become a central normative principle in evaluating climate models and their policy utility. However, not only are GCMs resource-intensive and intractable to interpret, they are also pervaded by over parameterization and inadequate attention to uncertainty.

The numerous problems with GCMs, and concerns that these problems will not be addressed in the near future given the current development path of these models, suggest that alternative model frameworks should be explored. We need a plurality of climate models that are developed and utilized in different ways for different purposes. For many issues of decision support, the GCM centric approach may not be the best approach.  However, a major challenge is that nearly all of the resources are being spent on GCMs and IPCC production runs, with little time and funds left over for model innovations.

The policy-driven imperative of climate prediction has resulted in the accumulation of power and authority around GCMs (Shackley), based on the promise of using GCMs to set emissions reduction targets and for regional predictions of climate change.   However, the IPCC is increasingly relying on much simpler models for setting emissions targets.  The hope for useful regional predictions of climate change using GCMs is unlikely to be realized based on the current path of model development.

With regards to fitness for purpose of global/regional climate models for climate adaptation decision making, an excellent summary is provided by a team of scientists from the Earth Institute and Red Cross Climate Center of Columbia University:

Climate model projections are able to capture many aspects of the climate system and so can be relied upon to guide mitigation plans and broad adaptation strategies, but the use of these models to guide local, practical adaptation actions is unwarranted. Climate models are unable to represent future conditions at the degree of spatial, temporal, and probabilistic precision with which projections are often provided which gives a false impression of confidence to users of climate change information.  (Nissan et al.)

GCMs clearly have an important role to play particularly in scientific research.  However, driven by the urgent needs of policy makers, the advancement of climate science is arguably being slowed by the focus of resources on this one path of climate modeling.  The numerous problems with GCMs, and concerns that these problems will not be addressed in the near future given the current development path, suggest that alternative frameworks should be explored .   This is particularly important for the science-policy interface.

JC reflections

In the AR5, the emphasis was on the Earth Systems Models, and their ever growing complexity in terms of adding more chemistry and some ice sheet dynamics.

In AR6, these complex climate models are revealed for what they are: very complicated and computationally intensive toys, whose main results are dependent on fast thermodynamic feedback processes (water vapor, lapse rate, clouds) that are determined by subgrid-scale parameterizations and and the inevitable model tuning.

With the very large range of climate sensitivity values provided by the CMIP6 models, we are arguably in a period of negative learning. And this is in spite of the IPCC AR6 substantially reducing the range of ECS from the long-standing 1.5-4.5C to 2.5 to 4C (reminder: I am not buying this reduction on the low end, more on this soon).

So what are we left with?

  1. Global climate models (ESMs) remain an important tool for understanding how the climate system works. However, we have reached the point of diminishing returns on this unless there is more emphasis on improving the simulation of modes of internal climate variability and advancing the treatment of solar indirect effects.
  2. We should abandon ECS as a policy-relevant metric and work on better understanding and evaluation of TCR and TCRE from historical data.
  3. In context of #1, I question whether the CMIP6 ESMs have much use in attribution studies.
  4. ESMs have lost their utility for policy applications. Policy applications are far more usefully achieved with climate emulator models. However, the use of climate emulators distances policy making from a basis in physics. This is particularly relevant for the legal status in various climate lawsuits of 21st century climate projections and the ESMs in various climate lawsuits.

While this is hidden in the Summary for Policy Makers, it is pretty significant:

A.1.3 The likely range of total human-caused global surface temperature increase from 18501900 to 20102019 is 0.8C to 1.3C, with a best estimate of 1.07C. It is likely that well-mixed GHGs contributed a warming of 1.0C to 2.0C, other human drivers (principally aerosols) contributed a cooling of 0.0C to 0.8C, natural drivers changed global surface temperature by 0.1C to 0.1C, and internal variability changed it by 0.2C to 0.2C. It is very likely that well-mixed GHGs were the main driver of tropospheric warming since 1979, and extremely likely that human-caused stratospheric ozone depletion was the main driver of cooling of the lower stratosphere between 1979 and the mid-1990s.

Compare this to the statements in the AR5 SPM:

It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human-induced contribution to warming is similar to the observed warming over this period.

Overall, the AR6 WG1 report is much better than the AR5, although I remain unimpressed by their increased confidence in a narrower range of ECS.

The bottom line is that the AR6 has broken the hegemony of the global climate models. The large amount of funding supporting these models towards policy objectives just became more difficult to justify.


Weather vs. Alarmism – Watts Up With That?



Brief Note by Kip Hansen — 20 October 2021

Channel 4, a British free-to-air public-service television network, sent a three-person TV crew to the Heartland Institutes’ 14th International Conference on Climate Change held this last weekend in Las Vegas, Nevada. I met and spoke with the two journalists. It took me less than ten seconds to realize that they had been sent to gather material for a scurrilous hit job piece on the conference. And that is exactly what they did.

The news clip (well, really just bit of video-climate-alarmism masquerading as journalism) exposes the featured Channel 4 reporter when, instead of asking questions and reporting the answers, her role is shown to be arguing for the alarmist viewpoint on camera.

I only mention this because the Smoking Gun of Climate Disaster in the broadcast news clip was Lake Mead, with its lowest water level “ever”.

The weather almost never co-operates . . . ask any sailor.

Atmospheric river storms to soak Bay Area, Northern California biggest in 9 months

“Three successive storms will surge in from the Pacific Ocean this week, forecasters said Tuesday, bringing what may be the most rain in nine months to drought-stricken Northern California and offering a promising start to winter after two years marked by record wildfires and dry conditions.

Two of those storms look like atmospheric rivers narrow, moisture-rich storms that play a critical role in the states water supply. The first, which was set to arrive late Tuesday night and continue into Wednesday morning, is likely to be a moderate storm. But another big one shaping up for Sunday night was upgraded to a category 5 on Tuesday, the highest in a five-level scale.

On average Northern California might get 1 or 2 of those a year, said Marty Ralph, director of the Center for Western Weather and Water Extremes at UC San Diego. We are looking at prolonged rain and some heavy rain.

The storms will dramatically reduce fire danger across Northern California, possibly all but ending it in some places. But they could also cause a risk of mudslides in some burned areas, particularly the Dixie Fire near Mount Lassen and the Caldor Fire near South Lake Tahoe.”

The last time California and the American Southwest had such an event was January 2021.

This new series of storms are predicted to drop up to two feet of snow in the high Sierras. 2017, which was the wettest year on record in much of California, also began with a series of similar soaking storms soaking in October. The incoming storms are predicted to be so serious, bring so much water and snow, that CalTrans has closed Highway 1 through the Big Sur area.

The weather is on our side and will help to debunk the Channel 4 nonsense.

This one series of three or four storms will not, of course, refill Lake Mead to historic levels, but a they are a good start to a wet winter for the parched and fire-scarred American West.

# # # # #

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2001-2019 Warming Driven By Increases In Absorbed Solar Radiation, Not Human Emissions – Watts Up With That?



Reposted from the NoTricksZone

ByKenneth Richardon18. October 2021

Three new studies affirm the increase in absorbed solar radiation associated with decreased reflection by clouds (albedo) has been the root cause of the positive Earth Energy Imbalance and global warming since the early 2000s.

Scientists (Loeb et al., 2021) have determined the rather uncertain positive trend in Earths Energy Imbalance (EEI) from 2005 to 2019, 0.5 W/m 0.47 W/m per decade1, is primarily due to an increase in absorbed solar radiation associated with decreased reflection by clouds.

CERES satellite data indicate clouds and surface albedo account for 89% of the absorbed solar radiation trend in the 21st century, whereas anthropogenic greenhouse gases account for but a tiny fraction of the trends in combined absorbed solar radiation and greenhouse effect forcing (reductions in emitted thermal radiation) during this period.

This very small human emissions/greenhouse gas impact is represented by the red Other (trace gases) bars in the graph below. In emitted thermal radiation, graph (e) shows the greenhouse gas impact is effectively offset by the cloud influence; both factors are cancelled out by temperature changes. This leaves the increase in absorbed solar radiation shown in graph (d) due to natural variations in clouds and surface albedo (SFC) as the primary driver(s) of top-of-atmosphere (TOA) flux forcing during the last two decades.

Image Source: Loeb et al., 2021

Other scientists (Dbal and Vahrenholt, 2021) have also concluded that the positive TOA net flux (+1.42 W/m) from increasing downwelling shortwave (SW) facilitated by a drop in cloudiness has been the major driving effect, dominating influence, and major heating cause explaining the 2001-2019 ocean heat content increase (240 ZJ).

The authors note these CERES satellite observations conflict with the assumption further global warming originates mainly from the LW [longwave] radiation capture caused by greenhouse gases, i.e., a decline in outgoing LW. In fact, the LW or greenhouse effect impact has been negative; it has contributed a net cooling influence (-1.1 W/m) over the last two decades.

Image Source: Dbal and Vahrenholt, 2021

The summarizing text from another new study (Ollila, 2021) bluntly asserts the substantial increase in downwelling SW radiation from 2000-2019 demonstrates there are natural climate drivers that have rapid and significant temperature impacts exceeding the anthropogenic drivers, and that any temperature increase since 2015-16 cannot be due to anthropogenic reasons.

Image Source: Ollila, 2021

These newer studies affirming the  21st increase in absorbed solar radiation has driven modern warming are further substantiated by a 2020 Nature journal paper (Delgado-Bonal et al., 2020) extending the positive (+3 W/m) cloud-albedo SW impact back to 1980.

[S]hortwave radiation is the main driver in the dynamics and plays a major role in the energy balance by affecting the longwave radiation field.
Our research supports the idea that clouds and albedo, which ultimately determine the SW radiation, are variables of the utmost importance for current climate change, in agreement with previous research about the changes in stratocumulus or energy imbalance in the last four decades for example. An increase in cloud coverage of 0.1 would, on average, lead to a 7% increase in spectrally integrated global average reflectance of shortwave radiation.
Image Source: Delgado-Bonal et al., 2020

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Weekly Climate and Energy News Roundup #475 – Watts Up With That?



The Week That Was: 2021-10-16 (October 16, 2021)
Brought to You by SEPP (
The Science and Environmental Policy Project


By Ken Haapala, President, Science and Environmental Policy Project (SEPP)

Presentation of the Fredrick Seitz Memorial Award: Comments Given at 14th International Conference on Climate Change by The Heartland Institute introducing David R. Legates, recipient of the 2021 Fredrick Seitz Memorial Award.

Physical Science develops with the constant conflict between ideas and evidence. What ideas best fit the physical evidence? When the physical evidence changes the ideas must change accordingly. Otherwise, the science becomes stagnant, dogmatic. That is what is happening to the science claimed by the UN Intergovernmental Panel on Climate Change (IPCC) and its followers, including many once noted US science institutions.

In 1988, the UN established the IPCC to (1) assess the scientific information related to changes in climate from emissions of greenhouse gases and 2) formulate realistic responses. The IPCC issued its first report in 1990. 

Since then, a great deal has changed including:

  1. human conditions have greatly improved thanks to the use of fossil fuels.
  • the physical evidence of what is happening in the atmosphere with increasing CO2 has greatly improved
  • the attitudes of Western governments to changing science have worsened

Over the last 30 years, one of the most remarkable changes is the tremendous reduction in people living in extreme poverty. Extreme poverty is defined as person having a local purchasing power of $1.90 a day. It is estimated in local currency and adjusted to inflation and similar issues. The estimates used here come from Our World In Data and were updated in 2019

As you see, 30 years ago 1.9 billion people 36% of the worlds population lived in extreme poverty, mostly in Asia. Extreme poverty is life on the edge of death. In 2018, 650 million lived on the edge, about 9% of the worlds population. The great reduction in those living in extreme poverty is despite an increase in population of about 43%.

From 1990 through 2018 the worlds CO2 emissions increased by 60%. Chinas CO2 emissions grew by 315%, more than three times. Today, Asia emits more CO2 than all other continents combined.


A second remarkable change is Space Age Technology which gives us the ability to observe and measure what is occurring in the atmosphere, where the greenhouse effect occurs. This evidence contradicts that early scientific speculation. Despite a 60% increase the influence of CO2 on global temperatures is modest, and not dangerous.


A third remarkable change is the obstinance of Western Governments and many western science institutions in ignoring the changing evidence. Contrary to the scientific method they are refusing to adjust their views, which they still call scientific, to the great expansion in physical evidence about the atmosphere and the effects of carbon dioxide. With mounting physical evidence, what began as a scientific speculation has drifted into world of science fiction and political myth.

Washington DC is a hotbed for science myths and attacking all who dare question them. Our honoree had already experienced what happens to physicists who challenge the accepted myths with physical evidence. In his experience in estimating precipitation, he always advocated those measurements must be checked and double checked, and when scientific concepts do not meet the evidence from experiments and observations, the concepts must be change. This winter, when given an opportunity he bravely stood up, and with the support of a few, declared certain myths popular in Washington are not science, and explained why.

Ladies and gentlemen, I have the privilege to present to you the honoree of the 2021 Fredrick Seitz Memorial Award, Dr. David Russell Legates


More details of the Heartland Conference will appear next week in a full TWTW

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