Tim Palmer (Oxford): Status and Future of Climate Modeling — Manifold Podcast #16

 

Tim Palmer is Royal Society Research Professor in Climate Physics, and a Senior Fellow at the Oxford Martin Institute. He is interested in the predictability and dynamics of weather and climate, including extreme events. 

He was involved in the first five IPCC assessment reports and was co-chair of the international scientific steering group of the World Climate Research Programme project (CLIVAR) on climate variability and predictability. 

After completing his DPhil at Oxford in theoretical physics, Tim worked at the UK Meteorological Office and later the European Centre for Medium-Range Weather Forecasts. For a large part of his career, Tim has developed ensemble methods for predicting uncertainty in weather and climate forecasts. 

In 2020 Tim was elected to the US National Academy of Sciences. 

Steve, Corey Washington, and Tim first discuss his career path from physics to climate research and then explore the science of climate modeling and the main uncertainties in state-of-the-art models. 

In this episode, we discuss: 

00:00 Introduction 

1:48 Tim Palmer's background and transition from general relativity to climate modeling 

15:13 Climate modeling uncertainty 

46:41 Navier-Stokes equations in climate modeling 

53:37 Where climate change is an existential risk 

1:01:26 Investment in climate research 

Links: 

 

Tim Palmer (Oxford University) 

https://www.ox.ac.uk/news-and-events/find-an-expert/professor-tim-palmer 

The scientific challenge of understanding and estimating climate change (2019) https://www.pnas.org/doi/pdf/10.1073/pnas.1906691116 

ExtremeEarth 

https://extremeearth.eu/ 

Physicist Steve Koonin on climate change

https://infoproc.blogspot.com/2021/04/how-physicist-became-climate-truth.html

Note added: For some background on the importance of water vapor (cloud) distribution within the primitive cells used in these climate simulations, see:

https://infoproc.blogspot.com/2017/06/epistemic-caution-and-climate-change.html

Low clouds trap IR radiation near the Earth, while high clouds reflect solar energy back into space. The net effect on heating from the distribution of water vapor is crucial in these models. However, due to the complexity of the Navier-Stokes equations, current simulations cannot actually solve for this distribution from first principles. Rather, the modelers hand code assumptions about fine grained behavior within each cell. The resulting uncertainty in (e.g., long term) climate prediction from these approximations is unknown.

How a Physicist Became a Climate Truth Teller: Steve Koonin

 

I read an early draft of Koonin's new book discussed in the WSJ article excerpted below, and I highly recommend it. 

See also Epistemic Caution and Climate Change.

Video above is from a 2019 talk discussed in this earlier post: Certainties and Uncertainties in our Energy and Climate Futures: Steve Koonin.

My own views (consistent, as far as I can tell, with what Steve says in the talk): 

1. Evidence for recent warming (~1 degree C) is strong. 

2. There exist previous eras of natural (non-anthropogenic) global temperature change of similar magnitude to what is happening now. 

3. However, it is plausible that at least part of the recent temperature rise is due to increase of atmospheric CO2 due to human activity. 

4. Climate models still have significant uncertainties. While the direct effect of CO2 IR absorption is well understood, second order effects like clouds, distribution of water vapor in the atmosphere, etc. are not under good control. The increase in temperature from a doubling of atmospheric CO2 is still uncertain to a factor of 2-3 and at the low range (e.g., 1.5 degree C) is not catastrophic. The direct effect of CO2 absorption is modest and at the low range (~1 degree C) of current consensus model predictions. Potentially catastrophic outcomes are due to second order effects that are not under good theoretical or computational control. 

5. Even if a catastrophic outcome is only a low probability tail risk, it is prudent to explore technologies that reduce greenhouse gas production. 

6. A Red Team exercise, properly done, would clarify what is certain and uncertain in climate science. 

Simply stating these views can get you attacked by crazy people.

Buy Steve's book for an accessible and fairly non-technical explanation of these points.

WSJ: ... Barack Obama is one of many who have declared an “epistemological crisis,” in which our society is losing its handle on something called truth. 

Thus an interesting experiment will be his and other Democrats’ response to a book by Steven Koonin, who was chief scientist of the Obama Energy Department. Mr. Koonin argues not against current climate science but that what the media and politicians and activists say about climate science has drifted so far out of touch with the actual science as to be absurdly, demonstrably false. 

This is not an altogether innocent drifting, he points out in a videoconference interview from his home in Cold Spring, N.Y. In 2019 a report by the presidents of the National Academies of Sciences claimed the “magnitude and frequency of certain extreme events are increasing.” The United Nations Intergovernmental Panel on Climate Change, which is deemed to compile the best science, says all such claims should be treated with “low confidence.” 

... Mr. Koonin, 69, and I are of one mind on 2018’s U.S. Fourth National Climate Assessment, issued in Donald Trump’s second year, which relied on such overegged worst-case emissions and temperature projections that even climate activists were abashed (a revolt continues to this day). “The report was written more to persuade than to inform,” he says. “It masquerades as objective science but was written as—all right, I’ll use the word—propaganda.” 

Mr. Koonin is a Brooklyn-born math whiz and theoretical physicist, a product of New York’s selective Stuyvesant High School. His parents, with less than a year of college between them, nevertheless intuited in 1968 exactly how to handle an unusually talented and motivated youngster: You want to go cross the country to Caltech at age 16? “Whatever you think is right, go ahead,” they told him. “I wanted to know how the world works,” Mr. Koonin says now. “I wanted to do physics since I was 6 years old, when I didn’t know it was called physics.” 

He would teach at Caltech for nearly three decades, serving as provost in charge of setting the scientific agenda for one of the country’s premier scientific institutions. Along the way he opened himself to the world beyond the lab. He was recruited at an early age by the Institute for Defense Analyses, a nonprofit group with Pentagon connections, for what he calls “national security summer camp: meeting generals and people in congress, touring installations, getting out on battleships.” The federal government sought “engagement” with the country’s rising scientist elite. It worked. 

He joined and eventually chaired JASON, an elite private group that provides classified and unclassified advisory analysis to federal agencies. (The name isn’t an acronym and comes from a character in Greek mythology.) He got involved in the cold-fusion controversy. He arbitrated a debate between private and government teams competing to map the human genome on whether the target error rate should be 1 in 10,000 or whether 1 in 100 was good enough. 

He began planting seeds as an institutionalist. He joined the oil giant BP as chief scientist, working for John Browne, now Baron Browne of Madingley, who had redubbed the company “Beyond Petroleum.” Using $500 million of BP’s money, Mr. Koonin created the Energy Biosciences Institute at Berkeley that’s still going strong. Mr. Koonin found his interest in climate science growing, “first of all because it’s wonderful science. It’s the most multidisciplinary thing I know. It goes from the isotopic composition of microfossils in the sea floor all the way through to the regulation of power plants.” 

From deeply examining the world’s energy system, he also became convinced that the real climate crisis was a crisis of political and scientific candor. He went to his boss and said, “John, the world isn’t going to be able to reduce emissions enough to make much difference.” 

Mr. Koonin still has a lot of Brooklyn in him: a robust laugh, a gift for expression and for cutting to the heart of any matter. His thoughts seem to be governed by an all-embracing realism. Hence the book coming out next month, Unsettled: What Climate Science Tells Us, What It Doesn’t, and Why It Matters.

Any reader would benefit from its deft, lucid tour of climate science, the best I’ve seen. His rigorous parsing of the evidence will have you questioning the political class’s compulsion to manufacture certainty where certainty doesn’t exist. You will come to doubt the usefulness of centurylong forecasts claiming to know how 1% shifts in variables will affect a global climate that we don’t understand with anything resembling 1% precision. ...

Note Added from comments:

If you're older like Koonin or myself you can remember a time when climate change was entirely devoid of tribal associations -- it was not in the political domain at all. It is easier for us just to concentrate on where the science is, and indeed we can remember where it was in the 1990s or 2000s.

Koonin was MUCH more concerned about alternative energy and climate than the typical scientist and that was part of his motivation for supporting the Berkeley Energy Biosciences Institute, created 2007. The fact that it was a $500M partnership between Berkeley and BP was a big deal and much debated at the time, but there was never any evidence that the science they did was negatively impacted. 

It is IRONIC that his focus on scientific rigor now gets him labeled as a climate denier (or sympathetic to the "wrong" side). ALL scientists should be sceptical, especially about claims regarding long term prediction in complex systems.

Contrast the uncertainty estimates in the IPCC reports (which are not defensible and did not change for ~20y!) vs the (g-2) anomaly that was in the news recently.

When I was at Harvard the physics department and applied science and engineering school shared a coffee lounge. I used to sit there and work in the afternoon and it happened that one of the climate modeling labs had their group meetings there. So for literally years I overheard their discussions about uncertainties concerning water vapor, clouds, etc. which to this day are not fully under control. This is illustrated in Fig1 at the link: https://infoproc.blogspot.c...

The gap between what real scientists say in private and what the public (or non-specialists) gets second hand through the media or politically-focused "scientific policy reports" is vast...

If you don't think we can have long-lasting public delusions regarding "settled science" (like a decade long stock or real estate bubble), look up nuclear winter, which has a lot of similarities to greenhouse gas-driven climate change. Note, I am not claiming that I know with high confidence that nuclear winter can't happen, but I AM claiming that the confidence level expressed by the climate scientists working on it at the time was absurd and communicated in a grotesquely distorted fashion to political leaders and the general public. Even now I would say the scientific issue is not settled, due to its sheer complexity, which is LESS than the complexity involved in predicting long term climate change!

https://en.wikipedia.org/wi... 

Klaus Lackner on Carbon Capture, Climate Change, and Physics

Steve and Corey talk to Klaus Lackner, director of the Center for Negative Carbon Emissions (CNCE) at Arizona State University and the first person to suggest removing CO2 from air to address climate change. Steve asks whether Klaus’ research was motivated by a tail risk of catastrophic outcomes due to CO2 build up. Klaus explains that he sees atmospheric CO2 as a waste management problem. Calculations show that removing human-produced carbon is energetically and economically viable. Klaus describes his invention, a “mechanical tree”, that passively collects CO2 from the air, allowing it to be stored or converted to fuel.

Note: Klaus, in theorist fashion, performs a number of Fermi estimates in real time during the discussion. To fully understand his reasoning, it might be useful to consult the transcript or replay the relevant parts of the interview.

Transcript

Klaus Lackner (Faculty Bio)

Center for Negative Carbon Emissions at ASU


man·i·fold /ˈmanəˌfōld/ many and various.

In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point.

Steve Hsu and Corey Washington have been friends for almost 30 years, and between them hold PhDs in Neuroscience, Philosophy, and Theoretical Physics. Join them for wide ranging and unfiltered conversations with leading writers, scientists, technologists, academics, entrepreneurs, investors, and more.

Steve Hsu is VP for Research and Professor of Theoretical Physics at Michigan State University. He is also a researcher in computational genomics and founder of several Silicon Valley startups, ranging from information security to biotech. Educated at Caltech and Berkeley, he was a Harvard Junior Fellow and held faculty positions at Yale and the University of Oregon before joining MSU.

Corey Washington is Director of Analytics in the Office of Research and Innovation at Michigan State University. He was educated at Amherst College and MIT before receiving a PhD in Philosophy from Stanford and a PhD in a Neuroscience from Columbia. He held faculty positions at the University Washington and the University of Maryland. Prior to MSU, Corey worked as a biotech consultant and is founder of a medical diagnostics startup.

Show Website

Elizabeth Kolbert on Climate Change: Impacts and Mitigation Technologies

Steve and Corey talk to Elizabeth Kolbert, author of The Sixth Extinction, about the current state of the climate debate. All three are pessimistic about the possibility that emissions will be substantively reduced in the near term, and they discuss technologies for removing carbon from the atmosphere. They explore uncertainty in the models regarding temperature rise and precipitation, and contemplate a billion people on the move in response to climate change and population increase. They ask: what is more of a threat to humanity in the coming century, runaway AI or runaway climate change?

Transcript

Elizabeth Kolbert (The New Yorker)

Field Notes from a Catastrophe: Man, Nature, and Climate Change

The Sixth Extinction: An Unnatural History

Jobs and AI

Carbon Capture


Related:

Epistemic Caution and Climate Change

Certainties and Uncertainties in our Energy and Climate Futures: Steve Koonin


man·i·fold /ˈmanəˌfōld/ many and various.

In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point.

Steve Hsu and Corey Washington have been friends for almost 30 years, and between them hold PhDs in Neuroscience, Philosophy, and Theoretical Physics. Join them for wide ranging and unfiltered conversations with leading writers, scientists, technologists, academics, entrepreneurs, investors, and more.

Steve Hsu is VP for Research and Professor of Theoretical Physics at Michigan State University. He is also a researcher in computational genomics and founder of several Silicon Valley startups, ranging from information security to biotech. Educated at Caltech and Berkeley, he was a Harvard Junior Fellow and held faculty positions at Yale and the University of Oregon before joining MSU.

Corey Washington is Director of Analytics in the Office of Research and Innovation at Michigan State University. He was educated at Amherst College and MIT before receiving a PhD in Philosophy from Stanford and a PhD in a Neuroscience from Columbia. He held faculty positions at the University Washington and the University of Maryland. Prior to MSU, Corey worked as a biotech consultant and is founder of a medical diagnostics startup.

Certainties and Uncertainties in our Energy and Climate Futures: Steve Koonin

This is a recent (2019) talk which gives a good overview of current climate science. Speaker is Steve Koonin, formerly Undersecretary for Science, US Department of Energy (Obama administration), Caltech Provost and theoretical physicist.

See earlier post Epistemic Caution and Climate Change (including comments).

My own views (consistent, as far as I can tell, with what Steve says in the talk):

1. Evidence for recent warming (~1 degree C) is strong.

2. There exist previous eras of natural (non-anthropogenic) global temperature change of similar magnitude to what is happening now.

3. However, it is plausible that at least part of the recent temperature rise is due to increase of atmospheric CO2 due to human activity.

4. Climate models still have significant uncertainties. While the direct effect of CO2 IR absorption is well understood, second order effects like clouds, distribution of water vapor in the atmosphere, etc. are not under good control. The increase in temperature from a doubling of atmospheric CO2 is still uncertain to a factor of 2-3 and at the low range (e.g., 1.5 degree C) is not catastrophic. The direct effect of CO2 absorption is modest and at the low range (~1 degree C) of current consensus model predictions. Potentially catastrophic outcomes are due to second order effects that are not under good theoretical or computational control.

5. Even if a catastrophic outcome is only a low probability tail risk, it is prudent to explore technologies that reduce greenhouse gas production.

6. A Red Team exercise, properly done, would clarify what is certain and uncertain in climate science.

Simply stating these views can get you attacked by crazy people.

Please tell me what is implausible about the following scenario: IPCC latest report has as its central projection a ~1.5 degree C warming over the next decades, assuming CO2 production continues at current levels. During those decades, battery technology could improve by an order of magnitude, due to intense R&D efforts. Solar energy cost and efficiency could also improve significantly over the same period. If these technological advances are realized by, e.g., 2040, we could substantially decrease our carbon footprint without wholesale dislocation of the world economy. It seems that huge R&D investment (nevertheless totally negligible relative to GDP or, e.g., military spending) in alternative energy and storage technologies is a no brainer...

Koonin rebuts some criticisms of his talk.

Manifold Podcast #23 Tim Searchinger: Biofuels vs Foods

Steve and Corey talk to Tim Searchinger about the unintended consequences of biofuels policies. Searchinger argues that these policies do not consider the opportunity costs of using plants for fuel rather than food. Combined with crazy carbon accounting principles, existing rules make cutting down trees in the US, shipping them to Europe and burning them in power plants count as carbon neutral under the Kyoto protocol. The three also discuss how eating less beef in the developed world along with educating women, family planning, and reducing child mortality in the developing world can decrease stress on land use and emissions.

Transcript

Creating a Sustainable Food Future: A Menu of Solutions to Feed Nearly 10 Billion People by 2050

Timothy Searchinger is a Research Scholar in the Center for Policy Research on Energy and the Environment at the Woodrow Wilson School, Princeton University.


man·i·fold /ˈmanəˌfōld/ many and various.

In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point.

Steve Hsu and Corey Washington have been friends for almost 30 years, and between them hold PhDs in Neuroscience, Philosophy, and Theoretical Physics. Join them for wide ranging and unfiltered conversations with leading writers, scientists, technologists, academics, entrepreneurs, investors, and more.

Steve Hsu is VP for Research and Professor of Theoretical Physics at Michigan State University. He is also a researcher in computational genomics and founder of several Silicon Valley startups, ranging from information security to biotech. Educated at Caltech and Berkeley, he was a Harvard Junior Fellow and held faculty positions at Yale and the University of Oregon before joining MSU.

Corey Washington is Director of Analytics in the Office of Research and Innovation at Michigan State University. He was educated at Amherst College and MIT before receiving a PhD in Philosophy from Stanford and a PhD in a Neuroscience from Columbia. He held faculty positions at the University Washington and the University of Maryland. Prior to MSU, Corey worked as a biotech consultant and is founder of a medical diagnostics startup.

Epistemic Caution and Climate Change

[ UPDATE: See 2019 post: Certainties and Uncertainties in our Energy and Climate Futures: Steve Koonin ]

I have not, until recently, invested significant time in trying to understand climate modeling. These notes are primarily for my own use, however I welcome comments from readers who have studied this issue in more depth.

I take a dim view of people who express strong opinions about complex phenomena without having understood the underlying uncertainties. I have yet to personally encounter anyone who claims to understand all of the issues discussed below, but I constantly meet people with strong views about climate change.

See my old post on epistemic caution Intellectual honesty: how much do we know?

... when it comes to complex systems like society or economy (and perhaps even climate), experts have demonstrably little predictive power. In rigorous studies, expert performance is often no better than random.  

... worse, experts are usually wildly overconfident about their capabilities. ... researchers themselves often have beliefs whose strength is entirely unsupported by available data.

Now to climate and CO2. AFAIU, the direct heating effect due to increasing CO2 concentration is only a logarithmic function (all the absorption is in a narrow frequency band). The main heating effects in climate models come from secondary effects such as water vapor distribution in the atmosphere, which are not calculable from first principles, nor under good experimental/observational control. Certainly any "catastrophic" outcomes would have to result from these secondary feedback effects.

The first paper below gives an elementary calculation of direct effects from atmospheric CO2. This is the "settled science" part of climate change -- it depends on relatively simple physics. The prediction is about 1 degree Celsius of warming from a doubling of CO2 concentration. Anything beyond this is due to secondary effects which, in their totality, are not well understood -- see second paper below, about model tuning, which discusses rather explicitly how these unknowns are dealt with.

Simple model to estimate the contribution of atmospheric CO2 to the Earth’s greenhouse effect
Am. J. Phys. 80, 306 (2012)
http://dx.doi.org/10.1119/1.3681188

We show how the CO2 contribution to the Earth’s greenhouse effect can be estimated from relatively simple physical considerations and readily available spectroscopic data. In particular, we present a calculation of the “climate sensitivity” (that is, the increase in temperature caused by a doubling of the concentration of CO2) in the absence of feedbacks. Our treatment highlights the important role played by the frequency dependence of the CO2 absorption spectrum. For pedagogical purposes, we provide two simple models to visualize different ways in which the atmosphere might return infrared radiation back to the Earth. The more physically realistic model, based on the Schwarzschild radiative transfer equations, uses as input an approximate form of the atmosphere’s temperature profile, and thus includes implicitly the effect of heat transfer mechanisms other than radiation.

From Conclusions:

... The question of feedbacks, in its broadest sense, is the whole question of climate change: namely, how much and in which way can we expect the Earth to respond to an increase of the average surface temperature of the order of 1 degree, arising from an eventual doubling of the concentration of CO2 in the atmosphere? And what further changes in temperature may result from this response? These are, of course, questions for climate scientists to resolve. ...

The paper below concerns model tuning. It should be apparent that there are many adjustable parameters hidden in any climate model. One wonders whether the available data, given its own uncertainties, can constrain this high dimensional parameter space sufficiently to produce predictive power in a rigorous statistical sense.

The first figure below illustrates how different choices of these parameters can affect model predictions. Note the huge range of possible outcomes! The second figure below illustrates some of the complex physical processes which are subsumed in the parameter choices. Over longer timescales, (e.g., decades) uncertainties such as the response of ecosystems (e.g., plant growth rates) to increased CO2 would play a role in the models. It is obvious that we do not (may never?) have control over these unknowns.

THE ART AND SCIENCE OF CLIMATE MODEL TUNING

AMERICAN METEOROLOGICAL SOCIETY MARCH 2017 | 589

... Climate model development is founded on well-understood physics combined with a number of heuristic process representations. The fluid motions in the atmosphere and ocean are resolved by the so-called dynamical core down to a grid spacing of typically 25–300 km for global models, based on numerical formulations of the equations of motion from fluid mechanics. Subgrid-scale turbulent and convective motions must be represented through approximate subgrid-scale parameterizations (Smagorinsky 1963; Arakawa and Schubert 1974; Edwards 2001). These subgrid-scale parameterizations include coupling with thermodynamics; radiation; continental hydrology; and, optionally, chemistry, aerosol microphysics, or biology.

Parameterizations are often based on a mixed, physical, phenomenological and statistical view. For example, the cloud fraction needed to represent the mean effect of a field of clouds on radiation may be related to the resolved humidity and temperature through an empirical relationship. But the same cloud fraction can also be obtained from a more elaborate description of processes governing cloud formation and evolution. For instance, for an ensemble of cumulus clouds within a horizontal grid cell, clouds can be represented with a single-mean plume of warm and moist air rising from the surface (Tiedtke 1989; Jam et al. 2013) or with an ensemble of such plumes (Arakawa and Schubert 1974). Similar parameterizations are needed for many components not amenable to first-principle approaches at the grid scale of a global model, including boundary layers, surface hydrology, and ecosystem dynamics. Each parameterization, in turn, typically depends on one or more parameters whose numerical values are poorly constrained by first principles or observations at the grid scale of global models. Being approximate descriptions of unresolved processes, there exist different possibilities for the representation of many processes. The development of competing approaches to different processes is one of the most active areas of climate research. The diversity of possible approaches and parameter values is one of the main motivations for model inter-comparison projects in which a strict protocol is shared by various modeling groups in order to better isolate the uncertainty in climate simulations that arises from the diversity of models (model uncertainty). ...

... All groups agreed or somewhat agreed that tuning was justified; 91% thought that tuning global-mean temperature or the global radiation balance was justified (agreed or somewhat agreed). ... the following were considered acceptable for tuning by over half the respondents: atmospheric circulation (74%), sea ice volume or extent (70%), and cloud radiative effects by regime and tuning for variability (both 52%).

Here is Steve Koonin, formerly Obama's Undersecretary for Science at DOE and a Caltech theoretical physicist, calling for a "Red Team" analysis of climate science, just a few months ago (un-gated link):

WSJ: ... The outcome of a Red/Blue exercise for climate science is not preordained, which makes such a process all the more valuable. It could reveal the current consensus as weaker than claimed. Alternatively, the consensus could emerge strengthened if Red Team criticisms were countered effectively. But whatever the outcome, we scientists would have better fulfilled our responsibilities to society, and climate policy discussions would be better informed.

Note Added: In 2014 Koonin ran a one day workshop for the APS (American Physical Society), inviting six leading climate scientists to present their work and engage in an open discussion. The APS committee responsible for reviewing the organization's statement on climate change were the main audience for the discussion. The 570+ page transcript, which is quite informative, is here. See Physics Today coverage, and an annotated version of Koonin's WSJ summary.

Below are some key questions Koonin posed to the panelists in preparation for the workshop. After the workshop he declared that The idea that “Climate science is settled” runs through today’s popular and policy discussions. Unfortunately, that claim is misguided.

The estimated equilibrium climate sensitivity to CO2 has remained between 1.5 and 4.5 in the IPCC reports since 1979, except for AR4 where it was given as 2-5.5.

What gives rise to the large uncertainties (factor of three!) in this fundamental parameter of the climate system?

How is the IPCC’s expression of increasing confidence in the detection/attribution/projection of anthropogenic influences consistent with this persistent uncertainty?

Wouldn’t detection of an anthropogenic signal necessarily improve estimates of the response to anthropogenic perturbations?

I seriously doubt that the process by which the 1.5 to 4.5 range is computed is statistically defensible. From the transcript, it appears that IPCC results of this kind are largely the result of "Expert Opinion" rather than a specific computation! It is rather curious that the range has not changed in 30+ years, despite billions of dollars spent on this research. More here.

Climate change priors and posteriors

I recommend this nice discussion of climate change on Andrew Gelman's blog. Physicist Phil, the guest-author of the post, gives his prior and posterior probability distribution for temperature sensitivity as a function of CO2 density. I guess I'm somewhere between Skeptic and Phil Prior.

As an aside, I think it is worth distinguishing between a situation where one has a high confidence level about a probability distribution (e.g., at an honest casino game like roulette or blackjack) versus in the real world, where even the pdf itself isn't known with any confidence (Knightian uncertainty). Personally, I am in the latter situation with climate science.

Here is an excerpt from a skeptic's comment on the post:

... So where are we on global climate change? We have some basic physics that predicts some warming caused by CO2, but a lot of positive and negative feedbacks that could amplify and attenuate temperature increases. We have computer models we can't trust for a variety of reasons. We have temperature station data that might have been corrupted by arbitrary "adjustments" to produce a warming trend. We have the north polar ice area decreasing, while the south polar ice area is constant or increasing. Next year an earth satellite will launch that should give us good measurements of polar ice thickness using radar. Let's hope that data doesn't get corrupted. We have some alternate theories to explain temperature increases such as cosmic ray flux. All this adds up to a confused and uncertain picture. The science is hardly "settled."

Finally the public is not buying AGW. Anyone with common sense can see that the big funding governments have poured into climate science has corrupted it. Until this whole thing gets an independent review from trustworthy people, it will not enjoy general acceptance. You can look for that at the ballot box next year.

For a dose of (justified?) certitude, see this angry letter, signed by numerous National Academy of Science members, that appeared in Science last week. See here for a systematic study of the record of expert predictions about complex systems. Scientists are only slightly less susceptible than others to group think.

Has global warming stopped?

A colleague sent me this analysis of recent warming trends. Note in the excerpt below there is an actual prediction, which I have bolded.

Please direct inquiries to Professor Bothun.

Global Temperature Is Continuing to Rise: A Primer on Climate Baseline Instability

G. Bothun and S. Ostrander, Dept of Physics, University of Oregon


... When represented this way, it seems clear that the El Nino/La Nina cycles are superposed on a steadily increasing slope that commences somewhere in the 1980-1985 period. The claim that global warm[ing] stopped in 1998, as applied to this diagram, shows that it also stopped in 1982, then again in 1985, and then in 1991, 1998, 2001, 2003, and 2008. In other words, we see continuous evidence of “mini-peaks” (or local maxima in the parlance of time series language) in the anomaly data which are simply smoothed over and missed when one plots annual data.

The current period is most likely a local minimum with respect to the last peak and one just need wait another 12 months or so, when we will return to increasing global monthly anomalies which then will be about +1 degree C in amplitude. Note finally that this data is using a 100 year baseline which is serving to somewhat suppress the actual amplitude of the positive residuals. The main point of this article, however, is not to determine the statistically best way to define the maximum amplitude of global rises in average land temperature, but rather to point out the significant fluctuations in the baseline due to the 4 phase AMO/PDO system and the El Nino/La Nina cycle will cause local maxima and minima in any time series data involving average temperatures.

On the basis of this data it would seem that we oscillate between a local maximum and a local minimum (on timescales of a couple of years) while the underlying trend is upwards and certainly not downwards. Consistent with that conclusion is the recent data from NOAA and NASA that March 2010 was the warmest March every within the time period shown above. When other factors are considered [which affect] the future amplitude of temperature increases, such as the water vapor feedback loop and the methane release of the Arctic permafrost, the argument that global warming peaked in 1998 will prove to be both erroneous and silly.

Climategate and the American Physical Society

I got this email message today. Again, I haven't done my homework on this issue, so I don't have a strong opinion. But the signatories to this email and (I suspect) a fair number of APS members do.

Dear fellow member of the American Physical Society:

This is a matter of great importance to the integrity of the Society. It is being sent to a random fraction of the membership, so we hope you will pass it on.

By now everyone has heard of what has come to be known as ClimateGate, which was and is an international scientific fraud, the worst any of us have seen in our cumulative 223 years of APS membership. For those who have missed the news we recommend the excellent summary article by Richard Lindzen in the November 30 edition of the Wall Street journal, entitled "The Climate Science isn't Settled," for a balanced account of the situation. It was written by a scientist of unquestioned authority and integrity. A copy can be found among the items at http://tinyurl.com/lg266u, and a visit to http://www.ClimateDepot.com can fill in the details of the scandal, while adding spice.

What has this to do with APS? In 2007 the APS Council adopted a Statement on global warming (also reproduced at the tinyurl site mentioned above) that was based largely on the scientific work that is now revealed to have been corrupted. (The principals in this escapade have not denied what they did, but have sought to dismiss it by saying that it is normal practice among scientists. You know and we know that that is simply untrue. Physicists are not expected to cheat.)

We have asked the APS management to put the 2007 Statement on ice until the extent to which it is tainted can be determined, but that has not been done. We have also asked that the membership be consulted on this point, but that too has not been done.

None of us would use corrupted science in our own work, nor would we sign off on a thesis by a student who did so. This is not only a matter of science, it is a matter of integrity, and the integrity of the APS is now at stake. That is why we are taking the unusual step of communicating directly with at least a fraction of the membership.

If you believe that the APS should withdraw a Policy Statement that is based on admittedly corrupted science, and should then undertake to clarify the real state of the art in the best tradition of a learned society, please send a note to the incoming President of the APS ccallan@pr****ton.edu, with the single word YES in the subject line. That will make it easier for him to count.

Bob Austin, Professor of Physics, Princeton
Hal Lewis, emeritus Professor of Physics, University of California, Santa Barbara
Will Happer, Professor of Physics, Princeton
Larry Gould, Professor of Physics, Hartford
Roger Cohen, former Manager, Strategic Planning, ExxonMobil

Climategate at Tierneylab

Be sure to look at the hundreds of comments!

Tierneylab: ... I’m not trying to suggest that climate change isn’t a real threat, or that scientists are deliberately hyping it. But when they look at evidence of the threat, they may be subject to the confirmation bias — seeing trends that accord with their preconceptions and desires. Given the huge stakes in this debate — the trillions of dollars that might be spent to reduce greenhouse emissions — it’s important to keep taking skeptical looks at the data. How open do you think climate scientists are to skeptical views, and to letting outsiders double-check their data and calculations?

People keep asking me about climate change, and I tell them I just don't have enough time to do the homework necessary to justify my having a strong opinion on the issue. Note, by simply making that statement I am being politically incorrect -- I think I am supposed to accept that the "experts" know what they are doing. (Just as the bond rating agencies and financiers knew what they were doing a few years ago :-)

Very few of the people with strong opinions on climate change have done the homework I refer to -- read the literature (including arguments on both sides), look at the data, etc. In the case of the housing and credit bubble I did do the homework and as a result I thought we were in a bubble back in 2004, that credit derivatives were dangerous, and that it might end badly.

I can say something with very high confidence: scientists are not immune to groupthink!


[A reader asks: what if you don't have the technical background to actually "do your homework" -- i.e., read the scientific literature? (Perhaps because your liberal arts education left you unable to use important tools necessary for understanding how the world works ;-) In that case, you are limited to an examination of the process by which the science is done -- are the incentives right? Could researchers be victims of groupthink? Can critics be heard, and do they have access to resources (such as the original data)? This is a sociological question -- is science working properly in this particular subfield? A final factor that should influence your confidence level is that the track record of experts studying complex systems is quite poor. ]

Help! -- climate change

Some of the readers of this blog know much more about climate change than I do. Could someone please comment on this web page of Eric Baum's, in which he claims the evidence for human causation is weak and that state of the art climate models are shoddy? (Excerpts below.) Baum is a brilliant guy -- former theoretical physicist and AI researcher. I've recommended his book on AI here before.

Greenhouse Gas global warming (as opposed to other sources) should be measured in the tropical troposphere, because the models say that is the signature of greenhouse gas warming: the tropical troposphere should warm at roughly twice the surface rate. To verify this, see for example Figure 9.1, p675, Vol 1 IPCC Report. http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter9.pdf (The whole report can be found at http://www.ipcc.ch/ipccreports/ar4-wg1.htm .)
This was always an embarrassment for global warmists, because the troposphere has never warmed much, but in the last few years its cooled. The tropical troposphere has now not warmed at all. See http://www.climateaudit.org/?p=3048 for the graph of temperature according to three satellite series since 1978.

The Radiosonde (weather balloon) data series is an independent measurement of the tropical troposphere temperature. It goes back to 1958 and is presumably extremely reliable, because all they are doing is sending thermometers up in balloons. You can see the time series at: http://www.climateaudit.org/wp-content/uploads/2008/06/hadat42.gif The graph is flat, and the most recent data point is the coldest.

...This shows that the IPCC's GCM's (Global Circulation Models) are wrong. Not that it can be too surprising that the GCM's are worthless since p 596 of the IPCC 4th report cautiously admitted they didn't know whether their GCM's had more data points or free parameters! Yet the GCM's are absolutely central to any argument for expecting warming by more than a few tenths of a degree by 2100, and to the amazingly porous argument the IPCC report gives to demonstrate man caused the alleged observed warming.

...The IPCC 4th report says "attribution of anthropogenic climate change is understood to mean demonstration that a detected change... is not consistent with alternative, physically plausible explanations."[p668] But the report contains several alternative possibilities that are said to be "not understood" or whose magnitude is said to be "largely unknown". For example, two are mentioned just in the last paragraph of 1.4.3. (p108): unknown large feedbacks from changes in solar irradiance, and the effects of galactic cosmic rays. Actually, as I point out in the above few paragraphs, cosmic rays seem to explain climate fluctuations extremely well. The IPCC devotes considerable space to the strawman that solar activity could directly affect the earth's temperature, but ignores the actual indirect means by which solar variation seems to affect temperature. Global Warmists routinely attack the strawman of direct solar effect any time the subject is raised.

Also, Mars, Jupiter, Triton, Neptune, and Pluto have recently been observed warming, suggesting some cause external to the earth, but none of them are mentioned anywhere in the 987 pages of the 4th Report. Another physically plausible explanation for recent warming (if indeed warming has actually occurred) as remarked by Lindzen would be thermal transfer from the deep oceans. The oceans and atmosphere are turbulent fluids prone to exchange heat in unpredictable ways over a wide range of time scales simply because chaotic systems do that kind of thing, which the computer models of the IPCC are completely inadequate to simulate.

Its also worth noting that intuitive physics (and pencil and paper calculation) says that greenhouse gas warming scales logarithmically. The theoretical reason for the effect is that CO2 molecules (for example) absorb and reflect certain wavelengths. But they only do it in certain wavelengths. Once you've got some molecules of CO2 in the air, the effect of each next molecule is less than the one before, because those wavelengths are already getting scattered, and mostly heat is already only getting out in other wavelengths. So even if you believed everything else, one's expectation would be that we've already seen the substantial majority of all the warming we will ever see, if we quintuple the CO2 from here. To believe otherwise, you have to rely in detail on the GCM's prediction of positive feedbacks, that they are not competent to calculate, to predict warming in the future that is several times greater than anything we've seen before.