But do the experts opinions actually reflect the scientific knowledge on these subjects?

The answer is no.

In fact, the experts’ opinions tended towards the extreme, despite recent science which should have reeled them in. Which is a lesson in and of itself.

How much confidence would you place in expert assessments such as the IPCC reports, when the experts themselves disregard some science in favor of others (namely the science that they themselves have been involved in), despite any good reasons to do so?

Not much would be my answer.

A prime example of experts disregarding scientific knowledge is found in the PNAS survey conducted by Kirsten Zickfeld and colleagues.

Zickfeld et al. interviewed 14 experts about what they thought the climate future holds in store under various scenarios of atmospheric carbon dioxide concentrations. The experts’ responses to the scenario in which atmospheric CO2 levels reach about 1000 parts per million (ppm) by the year 2200 is the one which got the most attention—predictably so, why pay any attention to outcomes which aren’t dramatic.

In fact, as evidence that the experts were themselves prone to the dramatic, Dr. Myles Allen (one of the experts interviewed), was quoted in the UK’s The Independent, that “We are certainly capable of committing ourselves to an emissions trajectory that make 1,000 ppm in 2200 almost inevitable if we make the wrong decisions over the next 20 years.”

This seems a little short-sighted and moralistic, but hey, these guys are experts.

And 13 out of 14 stated that there was a greater than 50% likihood that some sort of climate tipping point would occur by 2200 under the 1000ppm CO2 scenario while 9 of them put the probability as over 80%.

Undoubtedly, a leading factor in these beliefs comes down to the experts’ opinions as to what is the true value of the earth’s climate sensitivity. It turns out, that this has been a hard value to pin down—largely because uncertainties abound in both our understanding of the observed climate as well as how it got that way.

Zickfeld et al. report that the experts consider the leading cause of uncertainty about the behavior of the climate system to lie with cloud processes. Others causes consistently listed near the top were feedbacks involving ice and snow, water vapor feedback, and large-scale ocean circulation.

It is interesting to note that Zickfeld found that the experts had little confidence that scientific research would reduce the impacts of these uncertainties by half even if research budgets were increased by 3 times current levels.

Considering all that we don’t know, the Intergovernmental Panel on Climate Change (IPCC) can only state that the “likely” range (a confidence of between 66 and 90%) of the true value of the climate sensitivity lies between 2°C and 4.5°C, which, as Zickfeld explains, means that the IPCC thinks that there is just a 5% to 17% chance that the climate sensitivity is greater than 4.5°C.

But what to the experts think about the range of climate sensitivity? Figure 1 shows their expert opinion.

Figure 1. Range of values which are thought to contain the true value of the earth’s climate sensitivity, as given by 14 experts. The tick marks on the whiskers bound the 90% range, the boxes bound the 50% range and the small, thick horizonal mark reprents the median value of the distribution. The values in parentheses under the number of each reviewer is the probability that the climate sensitivity is greater than 4.5°C. (the grayed out boxes associated with some experts are how those experts responded to the question in a similar survey more than 10 years ago).

Now, before I go much further, let me discuss briefly who Zickfeld’s experts are. Probably a good half of them have been directly involved in research projects which have determined that very high climate sensitivity values were a distinct possibility, and exactly none of them were involved in research projects (such as those being carried out by Richard Lindzen or Roy Spencer) which suggest that the climate sensitivity is at (or below) the low end of the IPCC range.

So, the following results will hardly be surprising.

Zickfeld et al. report:

The IPCC report assesses that the “equilibrium climate sensitivity is likely to lie in the range 2– 4.5°C, with a most likely value of about 3°C.” IPCC defines likely as a 0.66–0.90 probability, which in Chapter 19, Working Group II (WGII) is interpreted as a 0.05–0.17 probability that climate sensitivity is >4.5°C. Examining the elicited distributions obtained from our experts, we find that 10 of the 14 experts placed >0.17 of their probability above 4.5 °C. [emphasis added]

So 10 of the 14 experts think the chance of a high sensitivity value is greater than that laid out in the IPCC. As a note, the other 4 experts listed the probability at 7%, 10%, 12% and 15%.

Even more enlightening is that 9 of the 14 experts consider a climate sensitivity of greater than 6°C as having a not insignificant 5% chance of being the true value.

What is so incredible about these numbers is that there is solidly argued scientific research (appearing in the peer-reviewed literature) that constrains the climate sensitivity range to a much greater degree than these experts do.

Most notable is a string of papers published by James Annan, a climate researcher at the Research Institute for Global Change of the Japan Agency for Marine-Earth Science and Technology and his colleagues. James argues that his research pretty strongly suggests that the upper end of the range of potential climate sensitivity is much more constrained than the experts realize (or admit to).

In his most recent paper on the subject, James concludes:

Based on some conservative assumptions regarding the value of independent estimates, we conclude that climate sensitivity is very unlikely (<5% probability) to exceed 4.5°C. We cannot assign a significant probability to climate sensitivity exceeding 6°C without making what appear to be wholly unrealistic exaggerations about the uncertainties involved. This represents a significant lowering of the previously-estimated bound.

Apparently, most of Zickfeld’s experts weren’t above “making wholly unrealistic exaggerations about the uncertainties involved” as 9 of them included a probability of 5% or more that the true climate sensitivity was above 6°C (and not a one had a probability as low as 5% for the climate sensitivity being above 4.5°C).

Clearly, the experts did not think too highly of James’ analysis.

All of this has left James shaking his head (from his review of the Zickfeld article):

So even though as far as I can tell everyone accepts that the fundamental points we make in our two papers are valid, they still stick to these old discredited results with long tails to high values. – in fact the answers are more alarmist than 15 years ago. Makes us wonder why we bother…

Read more of why James is disheartened at his blog post “Oh noes we’re all going die…by 2200.”

All of this shines interesting light on the latest entry over at the blog RealClimate—a prayer of sorts, that Gavin Schmidt picked up at a recent climate meeting which he offers for discussion:

Grant us…
The ability to reduce the uncertainties we can;
The willingness to work with the uncertainties we cannot;
And the scientific knowledge to know the difference.

The way I see it, there is real work being done to reduce the uncertainties on the estimate of the climate sensitivity, but the experts would rather not recognize these results and instead, they prefer to treat climate sensitivity as a type of uncertainty that can’t be known, because this allows them to better entertain the high end leading to future catastrophe and tipping points.

Which gets to the bottom of the bigger issue—that is, what is wrong with Assessment reports such as those from the IPCC.

Simply put, they reflect the opinion of experts rather than a comprehensive, or even unbiased, review of the scientific literature. The assumption that expert assessments draw upon the best scientific knowledge is a false one—what experts do drawn upon are their own ideas, some borne by their own work, and even if subsequent work seriously calls their own work into question, they stick to their old ideas. This is on display here, and also throughout the Climategate emails.

References:

Annan, J. D., and J. C. Hargreaves, 2006. Using multiple observationally-based constraints to estimate climate sensitivity. Geophysical Research Letters, 33, L06704.

Zickfeld, K., et al., 2010. Expert judgments about transient climate response to alternative future trajectories of radiative forcing. Proceedings of the National Academy of Sciences, doi:10.1073/pnas.0908906107.

One time in the House of Representatives [a colleague] told me a story about a proposition that a teacher put to a boy. He said, ‘Johnny, a cat fell in a well 100 feet deep. Suppose that cat climbed up 1 foot and then fell back 2 feet. How long would it take the cat to get out of the well?

Johnny worked assiduously with his slate and slate pencil for quite a while, and then when the teacher came down and said, ‘How are you getting along?’ Johnny said, ‘Teacher, if you give me another slate and a couple of slate pencils, I am pretty sure that in the next 30 minutes I can land that cat in hell.

The nation needs Johnny. In fact, it may be time we hired a team of people like Johnny for every large science-based policy proposal Congress contemplates funding.

Carbon Capture and Storage: A Known Boondoggle

Consider, for example, the $4.4 billion Congress is putting into carbon capture and sequestration (CCS) research, nearly half of that to come from the Kerry-Lieberman climate bill. As Robert Bryce points out in the New York Times, “That’s a lot of money for a technology whose adoption faces three potentially insurmountable hurdles: it greatly reduces the output of power plants; pipeline capacity to move the newly captured carbon dioxide is woefully insufficient; and the volume of waste material is staggering.”

Those of us familiar with the coal-fired power plant industry have long recognized that CCS may be slightly more than a pipe-dream, but will never be affordable or practicable for the vast majority of coal-fired plants. Yet no one in the bureaucracy has had the courage to stand up and refute this politically correct but scientifically bankrupt concept.

Lessons from a Broken Hockey Stick

Nor is CCS the only example. Perhaps the highest visibility science that needed a “Johnny” is the now infamous global warming hockey stick. Andrew Montford’s “The Hockey Stick Illusion – Climategate and the Corruption of Science” deconstructs the woeful practices leading to this canard that propelled the entire world toward economic investments that are likely as not to be entirely wasted.

In his book, Montford identifies individuals within the paleoclimatology community who argued that they would not have used the invalid data upon which the hockey stick depended. But, they did not come forward, nor were they allowed to “peer review” the work before its publication. And why was that?

It took an act of Congress to find a “Johnny” to sort out the hockey stick and explain why no one came forward. The resultant Wegman report concluded, among many other important things:

The politicization of academic scholarly work leads to confusing public debates. Scholarly papers published in peer reviewed journals are considered the archival record of research. There is usually no requirement to archive supplemental material such as code and data. Consequently, the supplementary material for academic work is often poorly documented and archived and is not sufficiently robust to withstand intense public debate. In the present example there was too much reliance on peer review, which seemed not to be sufficiently independent.

And Wegman recommended:

Especially when massive amounts of public monies and human lives are at stake, academic work should have a more intense level of scrutiny and review. It is especially the case that authors of policy-related documents like the IPCC report, Climate Change 2001: The Scientific Basis, should not be the same people as those that constructed the academic papers.

The “Plan B” Idea

Having indepdent peer review is not a new idea. In 2005, Steven Hayward suggested “Perhaps the time has come to consider competition as the means of checking the Intergovernmental Panel on Climate Change’s monopoly and generating more reliable climate science.”

The Heartland Institute made such an attempt with its “Non-Governmental International Panel on Climate Change” report and the Center for the Study of Carbon Dioxide and Global Climate has mounted an effort to continue this work. But these efforts have failed to produce a meaningful impact on the political process, largely because the authors do not operate within the “peer” community and do not publish in the peer-reviewed literature.

There are better models, however, and these could be adapted to science-based policy analyses. For example, by federal law, an investment prospectus must include sufficient specification of risk assumptions as to permit independent analysis of the proposal. In like measure, financial institutions’ annual reports require independent audit analysis before publication.

The key is independent replication of the analysis and evaluation of important assumptions.

In the cold war days, the military used an approach called “Team B.” This team (alternatively called the Red team) developed approaches to counter the efforts of Team A (the Blue team). Still in use today, it has some strengths and some weaknesses. Without question, however, it always sharpened the quality of Team A’s work, finding errors in analysis, weaknesses of assumptions and entire areas of interest that opened up Team A’s thought processes and analytical options.

Team B operated within the professional “community,” making its contributions instantly credible and mandatory for review by Team A and the eventual policy makers.

The Marshall Institute had engendered discussion of this approach for today’s scientific policy issues, as have members of the American Physical Society. In particular, Dr. William Happer, Cyrus Fogg Brackett Professor of Physics at Princeton University, member of the National Academy of Sciences, and Fellow of the American Physical Society (APS), has proposed a Team B approach within the APS. Without question, the APS has enough independent and qualified members to have been able to audit the critical work underlying the IPCC reports and inform journal publisher’s of the important analytical elements to which regular peer-reviewers should give special attention.

A Proposal

I have little confidence in Happer’s approach, however. It stands too far back from the critical scientific process and will make contributions too late in the policy process. Instead, we can take a page from the book of the existing science policy bureaucracy – environmental assessments.

Under the National Environmental Policy Act, a project using significant federal funds cannot move forward until some form of environmental assessment has been completed and approved. These assessments have, of course, been misused to delay and prevent projects. However, at their heart, they have significantly improved proposals with the potential to adversely impact the environment. Correcting to eliminate the pathologies of the process, something similar could be used in other areas.

In the context of science-based policy today, Team B would be the ne plus ultra peer-review group required for any scientific or engineering initiative (including grants and grant programs) that Congress or the Federal bureaucracy planned to fund above a trigger level, or which would have such an impact on the private sector. The trigger might be $500 million, for example.

Before Congress authorized expenditure of such funds, the bill sponsor would need to offer a Team B report that validated the basis otherwise offered to justify the expenditure. An National Science Foundation program manager wishing to fund a subject area that expands high-cost research would need a valid Team B analysis of the science to ensure the area of investigation is justified. The Department of Energy, the Interior Department and the Environmental Protection Agency would need a Team B report on their major research initiatives and regulatory proposals. Any major studies commissioned or conducted by the National Research Council (and its subsidiaries) would require a Team B review.

In every case, a Team B report would involve an independent replication of the analysis, including assumptions, selection and screening of data, logic of computer code, statistical analysis and presentation of data. The Team B report would have to demonstrate its independence, using the tools discussed in the Wegman report. 

This independence is a key aspect of a Team B approach. It would not be helpful to simply pit antagonists against each other; and, of course, one cannot permit the incestuousness observed in the Mann-Jones et al network. Rather, one wants a “one-off” approach.  In nearly every case, one would want a Team B to include a statistician familiar with the statistical methods used, but not familiar with the authors and perhaps only peripherally knowledgeable about the scientific subject. They can obtain the information about the subject from the subject matter specialists on the team. 

The real challenge is selecting subject matter specialists.  In cases where funding opportunities is controlled by cliques, there is even a greater problem. Because all Team B work should be done in the light of day, perhaps all one needs is an honest Team B.  (OK, call me Diogenes.) An open process, one that access the entire planet’s available and experienced scientific community through the internet, may be the guarantor of a quality project.

The Upside of Reform

While Wegman did not believe peer review ought to be through blogs, without question, without McIntyre’s efforts, as recorded on his blog site, Mann’s corrupt hockey stick would never have been exposed. A competent Team B could harvest the intellectual contributions from an engaged web-community to good effect, especially with regard to highly technical issues. Further, the anonymity of the web would allow specialists to provide critical information without having to be worried about being outcast by the specialists’ cliques.

Surely a Team B approach would evolve and mature over time. What is certain, however, is that even the threat of a Team B review would occasion a return to trustworthy science and a fundamental return to the bedrock principles of scientific inquiry. As Wegman, Montford and McIntyre have made unutterably clear, if we need heightened oversight of financial institutions, we surely need such heightened oversight of the science upon which we found science-related policies having large economic consequences.

Of course in the real world, if the politicians and/or EPA starts intervening in the energy sector, their actions will be far from the economist’s theoretical ideal. Then the case for such policy activism falls apart.

Frank’s Pros/Cons of Intervention

Frank’s opening paragraphs nicely summarize his views on climate policy:

FORECASTS involving climate change are highly uncertain, denialists assert — a point that climate researchers themselves readily concede. The denialists view the uncertainty as strengthening their case for inaction, yet a careful weighing of the relevant costs and benefits supports taking exactly the opposite course.

Organizers of the recent climate conference in Copenhagen sought, unsuccessfully, to forge agreements to limit global warming to 3.6 degrees Fahrenheit by the end of the century. But even an increase that small would cause deadly harm. And far greater damage is likely if we do nothing.

Frank goes on to quote a new MIT study, which paints an alarming scenario of damages from warming if world governments sit on their hands. In contrast, Frank argues that the cost to the economy of limiting greenhouse gases is not in the same ballpark. He sums up with, “In short, the cost of preventing catastrophic climate change is astonishingly small, and it involves just a few simple changes in behavior.”

So if the risks of inaction are potentially catastrophic, while the costs of preventive government measures are relatively trivial, then who but a fool or a stooge for Big Oil would question the need for immediate intervention?

Why Aren’t We Consulting the  “Scientific Consensus”?

The funny thing is, in order for me to present a less frightening scenario, I don’t have to dig up a paper from Richard Lindzen or a speech by James Inhofe. All I need to do is quote from the recent Economic Report of the President and the IPCC AR4.

From the Obama administration’s Economic Report, in a chapter ominously entitled, “TRANSFORMING THE ENERGY SECTOR AND ADDRESSING CLIMATE CHANGE” [.pdf], we learn:

[T]he projected losses for the most likely range of temperature changes are relatively modest. For example, at the Intergovernmental Panel on Climate Change’s most likely temperature increase of 3?C for a doubling of CO₂ concentration (concentrations in 2100 are likely to be higher), the projected decline is 1.5 percent of GDP. (Box 9-2, page 242, emphasis added)

To put that projected decline of 1.5 percent of GDP in context, note that the CBO puts the high-end estimate for the economic cost of Waxman-Markey above this figure (at 3.5 percent of GDP) for the year 2050. (Note that the two figures are measuring slightly different things, but the general point remains.)

In other words, we have the Obama administration’s own report admitting that the projected damages from “doing nothing” are lower than the high-end estimates of the cost of “doing something.” Granted, that might present a prima facie case for doing something, but it’s not nearly as open-and-shut as Frank would have you believe. Using the government’s own estimates, it’s entirely possible that government intervention would cause more damage than benefits, and that’s even with textbook policy implementation!

“Fat Tails”: The Small Chance of Catastrophe

Perhaps realizing that its admission of a likely 1.5 percent decline in the share of consumption in GDP would not inspire the public to gladly hand over the energy sector to the politicians, the president’s report went on to say:

The projected relationship between temperature changes and consumption losses is nonlinear—that is, the projected losses grow more rapidly as temperature increases. For example, while the projected loss for the first 3?C is 1.5 percent, the loss at 6?C is five times higher. And the estimated loss associated with an increase of 9?C is about 20 percent [of consumption’s share of GDP]…Overall, it is evident that policy based on the most likely outcomes may not adequately protect society because such estimates fail to reflect the harms at higher temperatures. (ibid, bold added)

Now we’re getting somewhere. A potential 20 percent hit to consumption is indeed frightening. But how likely is this outcome?

If we turn to the IPCC AR4, we have our answer, at least according to a suite of modeling teams across different emission scenarios:

To read the above chart, technically you need to integrate the curve over a range of temperature increases to find the probability that the actual warming will occur in that range. But simply eyeballing the chart shows that the Economic Report’s catastrophic 9C warming scenario has a virtually zero change of occurring.

Conclusion

I am not arguing that the MIT study is wrong, or that the CBO has correctly quantified the likely economic impacts of a cap-and-trade program. All I am pointing out is that the standard alarmist claims–as typified by Robert Frank–do not enjoy nearly as much evidence as their most vocal proponents would have us believe.

To take apart the case for climate alarmism, we don’t need to embrace the research of the “denialists.” We only need to look at the government and IPCC’s own reports.

While not an issue for estimates of future sea level rise (sea ice is floating ice which does not influence sea level), a significant expansion of Antarctic sea ice runs counter to climate model projections. As the errors in the climate change “assessment” reports from the IPCC mount, its aura of scientific authority erodes, and with it, the justification for using their findings to underpin national and international efforts to regulate greenhouse gases.

Some climate scientists have distanced themselves from the IPCC Working Group II’s (WGII’s) Fourth Assessment Report (AR4), Impacts, Adaptation, and Vulnerability, prefering instead  the stronger hard science in the Working Group I (WGI) Report—The Physical Science Basis. Some folks have even gone as far as saying that no errors have been found in the WGI Report and the process in creating it was exemplary.

Such folks are in denial.

As I document below, WGI did a poor job in regard to Antarctic sea ice trends. Somehow, the IPCC specialists assessed away a plethora of evidence showing that the sea ice around Antarctica has been significantly increasing—a behavior that runs counter to climate model projections of sea ice declines—and instead documented only a slight, statistically insignificant rise.

How did this happen? The evidence suggests that IPCC authors were either being territorial in defending and promoting their own work in lieu of other equally legitimate (and ultimately more correct) findings, were being guided by IPCC brass to produce a specific IPCC point-of-view, or both.

The handling of Antarctic sea ice is, unfortunately, not an isolated incident in the IPCC reports, but is simply one of many examples in which portions of the peer-reviewed scientific literature were cast aside, or ignored, so that a particular point of view—the preconceived IPCC point of view—could be either maintained or forwarded.

Background

The problems with the IPCC’s handling of the trends in Antarctic sea ice was first uncovered and presented a week or two ago in an article posted over at the World Climate Report—another blog with which I have been involved with for a long time.

In this MasterResource article, I have dug a bit deeper into what lies behind the IPCC’s “assessment” of the trends in Antarctic sea ice that is presented in its WGI Fourth Assessment Report. What I’ve uncovered clearly illustrates the difference between a “review” of the literature and an “assessment” of the literature. The former would include as much of the literature on the topic under consideration as possible, while the latter carefully selects from the literature to make a particular case. As such, the results of a “review” would be pretty constant across different assemblages of folks doing the reviewing, while the results of an “assessment” strongly depend on just who is doing the assessing. Case in point, compare the IPCC’s Fourth Assessment Report with the equally glossy and thick Assessment Report from the Nongovernmental International Panel on Climate Change (NIPCC). Both start with the same body of literature, and yet they arrive at completely different conclusions.

Getting into the Detail

This is clearly evident in the section on recent sea ice trends in Antarctica. The IPCC dedicates part of one paragraph to the topic (IPCC AR4 Chapter 4, Section 4.4.2.2, p. 350-351) incorporating one reference (“Comiso (2003)”) which turns out to be a book chapter (i.e. not part of the peer-reviewed literature). The NIPCC on the other hand dedicates two full pages to the subject and incorporates 14 citations from the peer-reviewed literature (NIPCC, Chapter 4, Section 4.2.1, p 152–154).

The IPCC concludes, after its brief analysis, that while there has been an apparent increase in the sea ice extent around Antarctica from 1979 through 2005, that the increase has been slight and not statistically significant.

The NIPCC, on the other hand, finds that the trend in Antarctic sea ice has been about 2 to 3 times as great as the IPCC reported and, in fact, is quite statistically significant.

True, the NIPCC Report was published after the IPCC Assessment, so it includes a few citations that were published in the literature subsequent to the IPCC inclusion deadline, but still, there were plenty of publications that were extant at the time of the IPCC preparation that should have better guided the IPCC finding.

For some reason, the IPCC opted to ignore the vast majority those papers (and associated datasets). Consequently, as we shall see, the NIPCC’s assessment turns out to be superior to the IPCC’s.

The fact that the IPCC’s assessment was extremely limited and narrow did not go unnoticed in the IPCC review process (the set of expert and government reviews for various drafts of the IPCC AR4 can be found here).

One commenter (Ola Johannessen, who himself has published on sea ice trends) complained about the First Order Draft of the AR4 Chapter 4 that:

Section 4.4.2.2 [the section on sea ice trends]: The presentation of hemispheric, regional and seasonal trends is also incomplete, misleading and biased to NASA work (Comiso).

To which the IPCC replied:

Taken into account in the revised text.

A look at the final, published version of Section 4.4.2.2 shows that, in fact, there is only one reference to data on sea ice trends, that to Comiso (2003). The only other reference in the section (Belchansky et al., 2005) is to explain reasons for interannual variability and the Belchansky et al. reference was already present in the First Order Draft. So it hardly seems like Johannessen’s comments were “taken into account,” instead it seems like they were ignored.

Johannessen further complains about IPCC’s use of only one sea ice dataset, commenting “There should be a sentence added before ‘An updated version of the analysis done by Comiso…’ (which, by the way, appears to an update that is not a published or accepted paper)” and then going on to suggest many additional references that should be added to this section. The IPCC responds:

“Taken into account with the inclusion of Johannessen et al. (2004) work. But AR4 is meant to be the most recent assessment, not a history of prior assessments. Updates of data sets using previously published methodology is acceptable for IPCC.”

Interesting. First, in the published version of Chapter 4, the reference to Johannessen et al. (2004) does not appear in the section of the Chapter 4 under discussion—so apparently the IPCC was just bluffing about including it. Second, the IPCC affirms that being an “assessment” doesn’t mean having to include all relevant literature (i.e., it includes only literature that it deems to be relevant). And third, that using updates of previously published datasets is acceptable in the IPCC process.

In this case, points 2 and 3 seem opposed to each other. For the IPCC has deemed one particular dataset, that of Comiso (2003), to be most relevant, despite the fact that several other “recent” datasets existed.

Let’s look into the IPCC’s reliance on Comiso (2003) a bit further (Comiso by the way was a contributing author to IPCC AR4 Chapter 4).

The IPCC reference of their sea ice data is to Comiso (2003) which is the following book chapter (available here):

Comiso, J.C., 2003: Large scale characteristics and variability of the global sea ice cover. In: Sea Ice – An Introduction to its Physics, Biology, Chemistry, and Geology [Thomas, D. and G.S. Dieckmann (eds.)]. Blackwell Science, Oxford, UK, pp. 112–142.

The analyses in this book chapter use a sea ice algorithm developed and improved by Dr. Josefino Comiso during the 1980s and 1990s (Comiso’s technique was known as the “Bootstrap” algorithm). At the same time, there was another algorithm to derive sea ice from satellite observations that had been developed and improved by Dr. Donald Cavalieri and colleagues during the same span (Cavalieri et al.’s technique was known as the “NASA Team” algorithm). Both algorithms produced pretty similar results when deriving sea ice extent in the Arctic, but in the Antarctic regions, the results—especially the trend results—differed rather significantly. This difference was well-recognized in the peer-reviewed scientific literature (e.g. Zwally et al., 2002; Comiso and Steffen, 2001). Comiso’s Bootstrap method produced a much smaller and insignificant increase in Antarctic sea ice while the NASA Team algorithm produced a larger, statistically significant increase. Another analysis, by Watkins and Simmonds (2000) produced a trend that agreed better with the NASA Team results than Comiso’s Bootstrap results.

All these facts were acknowledged by the researchers involved as evidenced by discussions in Zwally et al. (2002) and Comiso and Steffen (2001), with each group more or less showing more reliance on their own methodology.

Further, an update to the NASA Team algorithm (known as NASA Team version 2) was published by Markus and Cavalieri in 2000. This update had the impact of producing an even greater trend in the extent of Antarctic sea ice (over the original NASA Team algorithm) and enlarging the discrepancy with Comiso’s Bootstrap algorithm.

All of this was extant in the peer-reviewed literature at the time of the IPCC AR4 production and yet the IPCC “assessed” things this way:

Most analyses of variability and trend in ice extent using the satellite record have focused on the period after 1978 when the satellite sensors have been relatively constant. Different estimates, obtained using different retrieval algorithms, produce very similar results for hemispheric extent, and all show an asymmetry between changes in the Arctic and the Antarctic. As an example, an updated analysis done by Comiso (2003) spanning the period November 1987 through December 2005, is shown in Figure 4.8. [emphasis added]

The statement in bold above was well-established at the time to be wrong, at least as it applied to the Southern Hemisphere. So obviously, even at this point, it is clear that the IPCC had conducted an inaccurate “assessment” of the literature.

Not surprisingly, of the existing “retrieval algorithms,” the one which showed the smallest (and statistically insignificant) trend in the Southern Hemisphere was the one used in “Comiso (2003)” which was selected as the example used by the IPCC.

How convenient.

It is even somewhat debatable whether even the “updated analysis done by Comiso (2003)” showed an insignificant trend.

The First Order Draft of Chapter 4 contained the following illustration of Southern Hemisphere sea ice, along with the caption “Sea Ice extent anomalies … the Southern Hemisphere based on passive microwave satellite data… [l]inear trend lines are indicated for each hemisphere….the small positive trend in the Southern Hemisphere is not significant. (Updated from Comiso, 2003).”

Figure 1. Figure 4.4.1b from the IPCC AR4 Chapter 4 First Order Draft.

Notice two things, 1) the figure depicts monthly ice extent anomalies from November 1978 through October 2004, and 2) the trend through them seems to be statistically significant (i.e. the confidence range does not include zero), given in the illustration as 9089.2 +/- 2970.7 km²/year or 0.735 +/- 0.240%/dec.

Yet, for some reason, the accompanying text claims that the trend in Figure 4.4.1b is insignificant (AR4 First Order Draft, page 4-14, lines 9-10):

The Antarctic results show a slight but insignificant positive trend of 0.7 ± 0.2% per decade.

This inconsistency was brought to the IPCC Chapter 4 authors’ attention by several IPCC commenters. Commentor John Church wrote “I do not understand why this trend is insignificant – it is more than three times the quoted error estimates” and Stefan Rahmstorf wrote “How can a trend of 0.7 +/- 0.2 be ‘insignificant’? Is not 0.2 the confidence interval, so it is significantly positive?” The IPCC responded to both in the same manner “Taken into account in revised text.”

And boy did they ever!

The Second Order Draft of Chapter 4 included the following figure (which ultimately was the one included in the final publication):

Figure 2. Figure 4.4.1b from the IPCC AR4 Chapter 4 Second Order Draft (this graphic was Figure 4.8 in the IPCC AR4 published version of Chapter 4).

The caption still read “the small positive trend in the Southern Hemisphere is not significant” but now the trend had become “5.6 +/- 11 x 10³ km² per year.”

Note two things 1) the monthly sea ice anomalies were replaced by annual anomalies, and 2) the trend shrunk by 38% and now actually was statistically insignificant.

So how did this come about?

First off, the IPCC used a well known statistical trick to lower the significance of the increase—that is, switch from monthly values to annual values. This trick generally has little impact on the trend value, but can have a sizeable impact on the statistical confidence of the trend. A trend that is supported by a larger amount of individual data points (in this case, monthly values) has more statistical confidence than the same trend supported by fewer data point (in this case annual data values). So, by using annual data instead of monthly data, the IPCC effectively lowered the perceived confidence of the Southern Hemisphere sea ice trend.

Secondly, just how did the trend drop by 38% when adding another 13 months’ worth of observations? Well, it is not because of the influence of those extra months, as they fell very near the established trend line (in other words, they had little direct influence on the trend). And switching from monthly to annual data also wouldn’t do it. So it had to be something else. One possible explanation is that the figure from the First Order Draft was actually (mistakenly) depicting Comiso’s determination of the area of sea ice, rather than the extent of sea ice. There is a difference in definition between these terms. The sea ice extent is taken to mean the area which is covered by sea ice with a concentration of at least 15% (i.e. this includes regions that are 85% open water), while sea ice area is taken to be the actual area of sea ice itself (so the sea ice area is less than the sea ice extent). Under general circumstances, the two measurements are highly correlated, and their trends are very similar. However, in the case of the Comiso’s Bootstrap algorithm, the trends in Southern Hemisphere sea ice extent and sea ice area were largely different. This fact raised some flags of concern at the time. Zwally et al. (2002) noted that the Bootstrap sea ice extent trends were the odd man out of all datasets. The area trends were similar across retrieval algorithms (all were significantly positive, including Comiso’s Bootstrap) and the extent trends were similar to the area trends in all algorithms except Comiso’s Bootstrap algorithm. Zwally et al. (2002) took this to mean that something was likely wrong with the Bootstrap determinations of Southern Hemispheric sea ice extent (probably involving how data from two satellites was stitched together). Comiso and Steffen (2001) also noted the difference in the trend between sea ice area and extent produced by the Bootstrap algorithm, they attributed most of the difference to changes in how tightly the sea ice was packed together (a mechanism dismissed by Zwally et al.) but admitted that inter-satellite issues may also play a part in the trend differences.

Bottom line is that not only did the IPCC Chapter 4 authors have to carefully choose which sea ice retrieval algorithm to use, but they also had to be careful to use sea ice extent rather than sea ice area (somthing they quite possibly forgot that they needed to do in the First Order Draft of Chapter 4).

The IPCC justifies these decisions as being the result of their “assessment” of the topic and the literature—decisions that just so happen to minimize the apparent increase in Southern Hemispheric sea ice concentration. The result of the inclusion of any other then-extant dataset on Southern Hemispheric sea ice would have been to counter the IPCC’s “assessment” that the sea ice increase there was statistically insignificant.

Oh yeah, an “assessment” of a significant rise in Southern Hemispheric sea ice would have been quite inconvenient to another IPCC “assessment” that “[s]ea ice is projected to shrink in both the Arctic and the Antarctic under all SRES scenarios.” So, no doubt the IPCC Chapter 4 Coordinating Lead Authors got a big slap on the back from the IPCC brass for avoiding that potentially embarrassing problem.

Parenthetically, I bet it would be fun to see the emails associated with the production of AR4 Chapter 4!

One last thing.

Less than a year after the IPCC AR4 was published, Comiso reported that indeed there was a problem with the Bootstrap algorithm as it concerned Southern Hemispheric sea ice extent (Comiso and Nishio, 2008). Correcting that problem increased the observed trend in Antarctic sea ice extent from November 1978 to December 2005 to 14,645 km²/year—a highly statistically significant value that is 2.6 times higher than reported by the IPCC and virtually identical to the trend from the updated NASA Team algorithm, described by Markus and Cavalieri in 2000 but completely ignored by the IPCC. Basically, everyone but Comiso (and the IPCC) was right all along.

Figure 3. Annual Antarctic sea ice anomalies from three datasets: the one used by the IPCC (Comiso, 2003; red); another extant at the time of the IPCC production (Markus and Cavalieri, 2000; blue); and the update to the IPCC analysis (Comiso and Nishio, 2008; cyan). The trend in the latter two datsets are more than 2.5 times larger than the IPCC trend and both are statistically significant (the IPCC trend is not).

Conclusion

On the topic of Antarctic sea ice trends, the “consensus of scientists”—as the IPCC likes to call itself—was wrong, led astray by the extremely poor “assessment” of the scientific knowledge-base made by a very few people who were directly involved in preparing that section—people who were either being territorial in defending and promoting their own work, were being guided by higher-ups to produce a specific IPCC point-of-view, or both.

From all I have been able to find out about this so far (including enlightenment gained from the Climategate emails into how other sections of the AR4 were carefully constructed), I would rate it “extremely unlikely” (in IPCC parlance, less than 5% chance) that what transpired was dumb luck, born of the IPCC authors’ unfamiliarity with the peer-reviewed literature—the very thing they were supposed to be assessing.

I am not sure which case is the most embarrassing.

References:

Comiso, J.C., 2001. Studies of Antarctic sea ice concentrations from satellite data and their applications. Journal of Geophysical Research, 106, C12, 31361-31385.

Comiso, J. C., and F. Nishio, 2008. Trends in the sea ice cover using enhanced and compatible AMSR-E, SSM/I, and SMMR data. Journal of Geophysical Research, 113, C02S07, doi:10.1029/2007JC004257.

Cavalieri, D. J., P. Gloersen, C. L. Parkinson, J. C. Comiso, and H. J. Zwally, 1997. Observed hemispheric asymmetry in global sea ice changes. Science, 278, 1104–1106.

Cavalieri, D. J., C. L. Parkinson, P. Gloersen, J. C. Comiso, and H. J. Zwally, 1999. Deriving long-term time series of sea ice cover from satellite passive microwave multisensor data sets. Journal of Geophysical Research, 104, 15803–15814.

Markus, T., and D. Cavalieri, 2000. An enhancement of the NASA Team sea ice algorithm. IEEE Transactions on Geoscience and Remote Sensing, 38, 1387-1398.

Watkins, A. B., and I. Simmonds, Current trends in Antarctic sea ice: The 1990s impact on a short climatology, 2000. Journal of Climate, 13, 4441–4451.

Zwally, H.J., J. C. Comiso, C. L. Parkinson, D. J. Cavalieri, 2002. Variability of Antarctic sea ice 1979-1998. Journal of Geophysical Research, 107, C5, 3041, doi:10.1029/2000JC000733.

[Editor note: The author has added an update at the end showing why it can be reasonably argued that anthropogenic greenhouse gases may be responsible for less than half of the observed warming since the mid-20th century]

Back in December, the EPA announced that it had determined that greenhouse gases released by human activities “threaten the public health and welfare of current and future generations.” This “Endangerment Finding” is the first step toward EPA’s issuing regulations aimed at restricting GHG emissions in the U.S.

Unfortunately for the EPA, a major pillar of support of the Endangerment Finding—that “most” of the “observed warming” since the mid-20th century is from greenhouse gas emissions from human activities—has been shown by recent scientific research in major peer-reviewed scientific journals to be largely in doubt.

Add this result to the list of problems that seems to grow longer with each passing day as more IPCC gaffes are uncovered and Climategate emails are parsed. One has to wonder just how long it will be until the EPA is challenged to reconsider its Endangerment Finding.

The basis for the Engangerment Finding is contained in the EPA’s Technical Support Document for Endangerment and Cause or Contribute Findings for Greenhouse Gases under Section 202(a) of the Clean Air Act (TSD). The TSD does not describe any new, independent research carried out by the EPA (because they did not undertake any), but instead largely summarizes the findings of the Intergovernmental Panel on Climate Change (IPCC).

One of the key statements (from page 2 of the Executive Summary of the EPA’s TSD) is this—a simple mimic the IPCC AR4 finding:

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG [greenhouse gas] concentrations.

As I shall show, this statement is no longer tenable.

Background

First off, here is my take on what the EPA/IPCC is claiming.

For “most” I’ll assume “more than half.” For “observed increase in global temperature” I’ll assume the linear least-squares regression trend through the most recent version of the global temperature dataset compiled jointly by the U.K.’s Hadley Center and Climate Research Unit (dataset HadCRUT3). There are other global temperature compilations (most notably from NASA and NOAA) and while there are certainly notable differences over the short run, over the longer term, they are very similar. “Since the mid-20th century” I’ll take as 1950. The EPA defines what it means by “very likely” in the Table I reproduced below—they mean “with a 90-99% probability.” And for “observed increase in GHG concentrations”, I’ll assume the greenhouse gases explicitly mentioned by the EPA (CO2, CH2, N2O, HFCs, PFCs, SF6).

TABLE 1. EPA’s “Description of likelihood”

Likelihood refers to a probabilistic assessment of some well defined outcome having occurred or occurring in the future, and may be based on quantitative analysis or an elicitation of expert views. When authors evaluate the likelihood of certain outcomes, the associated meanings are:

Virtually certain ………. >99% probability of occurrence

Very likely ………. 90 to 99% probability

Likely ………. 66 to 90% probability

About as likely as not ……….. 33 to 66% probability

Unlikely ……… 10 to 33% probability

Very unlikely ……… 1 to 10% probability

Exceptionally unlikely ………. <1% probability

As to what the “observed increase in global average temperature since the mid-20th century” has been, I present Figure 1—the annual HadCRUT3 global temperature record from 1950 to 2009. The trend line has value of 0.117°C/decade which amounts to a total temperature increase of 0.702C over the 60 years from 1950.

Figure 1. Observed global temperature history, 1950-2009 (data source: Hadley Center).

So that’s what we are starting with. The EPA is 90 to 99% certain that at least 0.35°C of warming in the extant (“observed”) record is from GHG emissions from human activity.

Now, let’s see what happens when we start to factor in recent findings.

Corrections to the “Observed” Record

First off, about a year after the IPCC released its AR4 report (from which the EPA took its statement), David Thompson and colleagues published a paper in Nature magazine titled “A large discontinuity in the mid-twentieth century in observed global-mean surface temperature.” In it, they documented how a change in observing practices before and after World War II produced a cold bias in the sea surface temperatures that were incorporated into the compilations of global average temperatures (see here and here for more details). Thompson et al. were unable to correct this bias (so it remains in the extant “observed” global temperature histories) but suggested that:

The adjustments immediately after 1945 are expected to be as large as those made to the pre-war data (~0.3°C), and smaller adjustments are likely to be required in SSTs through at least the mid-1960s, by which time the observing fleet was relatively diverse and less susceptible to changes in the data supply from a single country of origin.

The U.K.’s The Independent newspaper reproduced a graphic (from by the Climate Research Unit) that generally illustrated what the correction to the dataset may look like when it is finally applied.

The Independent’s chart basically shows what the Thompson et al. paper described—about a +0.3°C correction after about 1945 slowly declining to zero by the mid-1960s.

Figure 2 shows what happens when I apply this correction to the “observed” data in Figure 1 and then re-calculate the temperature change. The overall warming trend declines from the “observed” rate of 0.116°C/decade to a “corrected” rate of 0.092°C/decade. So EPA’s “observed increase in global average temperatures since the mid-20th century” has now dropped from 0.702°C to a “corrected” value of 0.552°C and 21% of EPA’s increase from “anthropogenic GHG” increases has now vanished, lost to errors in the observed data.

Figure 2. Observed global temperature history, 1950-2009 (black). “Corrected” global temperature history (following to Thompson et al., 2008) (red line).

Stratospheric Water Vapor

Now consider the results of a paper published just a few weeks ago in Science magazine by Susan Solomon and colleagues. They report that variations in the water vapor content in the lower stratosphere (apparently largely unrelated to GHG changes) have a large influence on the rate of global temperature change for periods of a decade or more. In fact, since 1980 (the start of the data analyzed), an overall increase in stratospheric water vapor content as been responsible for perhaps 15% of the overall temperature increase.

It is impossible from Solomon et al.’s analysis to know what went on prior to 1980, so, for lack of any other guidance, I’ll assume that no changes took place (or, that the net change was zero) from 1950 to 1980. I’ll then back the 15% warming influence from stratospheric water vapor changes since 1980 out of the “corrected” data in Figure 2. The warming I am left with is shown in Figure 3.

The overall trend declines to 0.081°C/decade (or a total rise of 0.486°C).

Now the EPA’s “observed increase in global average temperatures since the mid-20th century” has dropped from 0.702°C down to 0.486°C—and about 31% of increase from anthropogenic GHGs is gone.

Figure 3. Observed global temperature history, 1950-2009 (black). “Corrected” global temperature history (red line). “Corrected” temperature history with general influence of stratospheric water vapor (according to Solomon et al., 2010) removed (green line).

Influence of Black Carbon

Finally, consider the results from Ramanathan and Carmichael published in Nature Geoscience last year. These researchers reviewed the scientific understanding of how black carbon aerosols (aka soot) warm the earth’s climate. Black carbon is not a GHG. Black carbon warms the earth by directly absorbing reflected solar radiation and also by darkening the surface of snow and ice when it is deposited there (and enhances melting). Ramanathan and Carmichael determined that in toto black carbon has been responsible for about 25% of the overall warming.

The result of factoring out this non-GHG warming is illustrated in Figure 4. The 1950-2009 trend drops to 0.061°C/decade.

Figure 4. Observed global temperature history, 1950-2009 (black). “Corrected” global temperature history (red line). “Corrected” temperature history with general influence of stratospheric water vapor (according to Solomon et al., 2010) removed (green line). “Corrected” temperature history with general influence of stratospheric water vapor (according to Solomon et al., 2010) removed and the influence of black carbon (according to Ramanathan and Carmichael, 2009) removed (blue line).

The remaining warming—that which possibly could be caused by anthropogenic GHG increases—now stands at about 0.366°C—or just 52% of the EPA’s “observed” increase.

Conclusion—The EPA is Wrong

And I have only included the best estimates from Solomon et al. and Ramanathan and Carmichael. In fact, both studies include a range of estimates. Had I used the low end of the ranges, the remaining warming from GHGs would have been quite a bit less than 50% of the “observed” warming.

Also, I used a pretty conservative “correction” based on Thompson et al. Others contend that the “correction” should be larger, and in and of itself could invalidate the EPA/IPCC “most likely” description.

And, I didn’t include any warming from things such as urbanization, land-use change, site changes, or other natural variability—which have been by some studies to have a detectable (warming) impact.

So, if we take what the best science gives us, we find that pretty close to half of the warming that is currently indicated by the extant global temperature datasets may be from influences other than anthropogenic greenhouse gas increases—perhaps a bit less, perhaps a bit more.

Heading back to the EPA’s Description of Likelihood Table (above) we find that instead of “very likely,” probably the most apropos descriptor is found a couple of lines down, the one that encompasses a 33 to 66% probability—or “about as likely as not.”

Somehow, I think that if the EPA had written:

It is about as likely as not that most of the observed increase in global average temperatures since the mid-20th century is due to the observed increase in anthropogenic GHG concentrations.

that EPA’s justification for their Endangerment Finding would “very likely” have been considerably less compelling.

IPCC mistakes, Climategate perversions, and now new major scientific findings all demand the same thing—that EPA reconsider its Endangerment Finding as the validity of its scientific underpinnings is badly in need of update and reappraisal.

Update: Febuary 12, 2010

I have had several inquiries into what the remaining warming would look like if I incorporated the potential effect of non-climatic warming influences (e.g., urbanization, other landscape changes, instrument changes, network quality, etc.). I ran through a middle-of-the road estimate in Comment#6, that I’ll now move up into the post.

It goes something like this:

It is hard to know what a middle-of-the-road estimate from non-climatic influences on the land surface temperature observations may be. Brohan et al. (who developed the HadCRUT3 record) estimate the influence to be 0.005°C/decade. McKitrick and Michaels (2007) on the other hand, estimate it to be nearly 50% of the trend in the land record. This probably defines the range on influence.

Since the land only makes of 30% of the planet, each of the above estimates must be roughly reduced by 70% to be applied to the global record (details may vary). Or, respectively, 0.002°C/decade and 15%.

Applying each to the “corrected” decadal rate from 1950 to 2009 (which is 0.092°C/decade), yields 0.090°C/dec (from Brohan et al.) and 0.078°C/dec (from McKitrick and Michaels).
So, erring on the conservative side, let’s take 0.085°C/decade as the observed rate after correcting for the Thompson et al. error and non-climatic warming.

Working through the rest of my calculations (i.e., stratospheric water vapor and then black carbon) using the new 0.085°C/decade baseline leaves a trend of 0.056°C/decade that could potentially be from anthropogenic GHGs, or a total potential temperature rise of 0.337°C—which is 48% of the current “observed” value—or less than half of the current “observed” warming from the mid-20th century.

I’ve created a new, simplified chart to show the total effect of all the non-GHG adjustments (that I considered, perhaps there are others) to the “observed” temperature history. The black red line in the Figure below is the original warming trend as contained in the most-up-to-date “observed” temperature record, and the red blue line is the remaining (“adjusted”) trend after all non-GHG influences have been removed. The remaining trend is just 48% of the original trend. In other words, it can be reasonably argued that anthropogenic GHGs could be responsible for a minority of the observed warming since the mid-20th century.

Update Figure. Global temperature history, 1950-2009. The black red line in the Figure is the original warming trend as contained in the most-up-to-date “observed” temperature record (HadCRUT3), and the red blue line is the remaining (“adjusted”) trend after non-GHG influences have been removed.

References:

Ramanathan V., and G. Carmichael, 2009. Global and regional climate changes due to black carbon. Nature GeoScience, 1, 221-227.

Solomon, S., et al. 2010. Contributions of stratospheric water vapor to decadal changes in the rate of global warming. Science, published on-line January 28, 2010.

Thompson, D., et al., 2008. A large discontinuity in the mid-twentieth century in observed global-mean surface temperature. Nature, 453, 646-649.

Recent events have shown, rather embarrassingly, that the IPCC is not “the” consensus of scientists, but rather the opinions of a few scientists (in some cases as few as one) in various subject areas whose consensus among themselves is then kludged together by the designers of the IPCC final product who a priori know what they want the ultimate outcome to be (that greenhouse gases are leading to dangerous climate change and need to be restricted). So clearly you can see why the EPA (who has a similar objective) would decide to rely on the IPCC findings rather than have to conduct an independent assessment of the science with the same predetermined outcome. Why go through the extra effort to arrive at the same conclusion?

The EPA’s official justification for its reliance on the IPCC’s findings is that it has reviewed the IPCC’s “procedures” and found them to be exemplary.

Below is a look at some things, recently revealed, that the IPCC “procedures” have produced. These recent revelations indicate that the “procedures” are not infallible and that highly publicized IPCC results are either wrong or unjustified—which has the knock-on effect of rendering the IPCC an unreliable source of information. Unreliable doesn’t mean wrong in all cases, mind you, just that it is hard to know where and when errors are present, and as such, the justification that “the IPCC says so” is no longer sufficient (or acceptable).

Himalayan Glaciers

The IPCC has actually admitted that, in at least one area, its procedures have failed:

…It has, however, recently come to our attention that a paragraph in the 938 page Working Group II contribution to the underlying assessment refers to poorly substantiated estimates of rate of recession and date for the disappearance of Himalayan glaciers. In drafting the paragraph in question, the clear and well-established standards of evidence, required by the IPCC procedures, were not applied properly.

The Chair, Vice-Chairs, and Co-chairs of the IPCC regret the poor application of well-established IPCC procedures in this instance. This episode demonstrates that the quality of the assessment depends on absolute adherence to the IPCC standards, including thorough review of “the quality and validity of each source before incorporating results from the source into an IPCC Report”. We reaffirm our strong commitment to ensuring this level of performance.

It turns out, that in this case of Himalayan glaciers (apparently a favored topic of the IPCC head Dr. Rajendra Pachauri for raising funds for a non-profit that he heads), the IPCC’s findings—that the glaciers would largely disappear by the year 2035 (and endanger the water supply for hundreds of millions of people, as well as lead to increased avalanches and mudslides) as a result of anthropogenic global warming—were apparently based on some comments made by one researcher to the press. Those statements were later included in a World Wildlife Fund report that was the source cited by the IPCC.

Dr. Pachauri vehemently denied accusations of bad procedures when they were first made, going as far as calling evidence supporting the accusations “voodoo science”. Now, with the IPCC’s admission of its errors, an apology is being sought from Dr. Pauchari becasue of his remarks.

The latest scuttlebutt on this issue is that several folks in the IPCC knew of these problems for some time, but that they allowed them to perpetuate anyway and that other attempts to correct them by other IPCC scientists were lost in the mail.

This doesn’t speak so highly for the “procedures.”

Attribution of Increasing Damages to Rising Temperatures

Another issue which has gotten the IPCC’s attention in recent days has been its attribution of increasing weather-related losses to rising temperatures from human activities. In this case, the IPCC decided to issue a statement in which it denied that its “procedures” went astray—despite clear and growing evidence to the contrary. Such a denial in the face of mounting evidence seems like it could do even more harm than actually admitting another goof (but then again, how many major goofs can the IPCC really admit to without having to scrap the whole thing?).

The problems contained in the IPCC assessment have been well-documented by a series of posts by Roger Pielke Jr. at his blog (here, here, here, and here). Pielke Jr. builds a pretty convincing case that the IPCC gave short shrift to the body of peer-reviewed literature that concluded that a clear linkage between the rising levels of weather-related damages and rising temperatures was not yet demonstrable. The rapidly growing effect of demographic changes (population, wealth, etc.) overwhelms the influence of the weather and confuses issues of attribution. Yet, somehow, the IPCC’s assessment established that increasing losses were linked to rising temperatures. Pielke Jr. traces this to a “single non-peer reviewed” study “cherrypicked” from a “workshop.” Dr. Pielke Jr. had this to say about the IPCC’s recent statement upholding its findings and its claims that “[i]n writing, reviewing, and editing this section, IPCC procedures were carefully followed to produce the policy-relevant assessment that is the IPCC mandate”:

Carefully followed procedures? Let’s review: (a) The IPCC relied on an unpublished, non-peer reviewed source to produce its top line conclusions in this section, (b) when at least two reviewers complained about this section, the IPCC ignored their complaints and invented a response characterizing my views. (c) When the paper that this section relied on was eventually published it explicitly stated that it could not find a connection between rising temperatures and the costs of disasters.

Pielke Jr. continued:

This press release from the IPCC would have been a fine opportunity to set the scientific and procedural record straight and admit to what are obvious and major errors in content and process. Instead, it has decided to defend the indefensible, which any observer can easily see through. Of course there is no recourse here as the IPCC is unaccountable and there is no formal way to address errors in its report or its errors and misdirection via press release. Not a good showing by the IPCC.

Basically, with regards to this issue, the IPCC “consensus of scientists” isn’t even the consensus of the leading scientists actively studying the topic, but reflects the wishful thinking of one or two chapter authors and, no doubt, the IPCC designers, as well.

Medieval Warm Period

Many more examples of the IPCC “procedures” can be found courtesy of the Climategate emails.

For instance, in Chapter 6, the paleoclimate chapter of the IPCC’s most recent Fourth Assessment Report (AR4), it is the strong sentiment of one of the chapter’s coordinating lead author, Jonathan Overpeck, that he wants to dismiss the Medieval Warm Period (MWP)—a period of relatively high temperatures that occurred about a thousand years ago. If the MWP were found to be as warm as recent conditions, then the possibility that natural processes may play a larger role in recent warming is harder to ignore—thus the need to dismiss it. The task of doing so fell on Keith Briffa, who developed the contents of a special box in IPCC AR4 Chapter 6 that was apart from the main text and which focused on the WMP. Here’s the advice issued to Briffa by Overpeck:

I get the sense that I’m not the only one who would like to deal a mortal blow to the misuse of supposed warm period terms and myths in the literature. The sceptics and uninformed love to cite these periods as natural analogs for current warming too – pure rubbish.

So, pls DO try hard to follow up on my advice provided in previous email. No need to go into details on any but the MWP, but good to mention the others in the same dismissive effort.

Briffa attempted to complete his task by presenting a well-chosen collection of data that showed that while some proxy temperature reconstructions did show a warm period about 1,000 years ago, others did not. He concluded that a more complete picture indicated that the higher temperatures during the MWP were “heterogeneous” (regionalized), while the warming of the late 20th century has been “homogeneous” (i.e. much broader in spatial extent)—confirming that current conditions were likely unprecedented during the past 1,300 years. Briffa received congratulations for a job well done by Overpeck:

[A]ttached is Keith’s MWP box w/ my edits. It reads just great – much like a big hammer. Nice job.”

Thus, that conclusion driven by Overpeck’s desires, written by Briffa, perhaps reviewed by the chapter’s other authors (with varying degrees of knowledge about the subject), is now preserved as “the consensus of scientists.

But apparently, that consensus isn’t accepted by other leading paleoclimate researchers. In a peer-reviewed article published in 2009 in the journal Climatic Change, paleo-researchers Jan Esper and David Frank carefully re-examined the same proxy temperature reconstructions used by Briffa and came to conclude that the IPCC was unwarranted in declaring that the temperatures during the MWP were more heterogeneous than now. Here is the abstract from that paper:

In their 2007 report, IPCC working group 1 refers to an increased heterogeneity of climate during medieval times about 1000 years ago. This conclusion would be of relevance, as it implies a contrast in the spatial signature and forcing of current warmth to that during the Medieval Warm Period. Our analysis of the data displayed in the IPCC report, however, shows no indication of an increased spread between long-term proxy records. We emphasize the relevance of sample replication issues, and argue that an estimation of long-term spatial homogeneity changes is premature based on the smattering of data currently available.

Summary

So here we have multiple examples of the IPCC “procedures” and how “the consensus of scientists” is formed. In one case, the “consensus” was formed from comments made by a single scientist to the press; in another, the IPCC “consensus” conflicts with the consensus of scientists actually active in the topic of concern; and in the third case, the IPCC “consensus” is driven by the desires of one of the coordinating lead authors, and is now disputed by other members of the field. Others examples seem to be coming to the light daily (see here about conclusions regarding future agricultural productivity in Africa, or here about the IPCC pushing preconceived ideas).

In light of what we now know, I suggest that from now on, all IPCC products come with the following warning label:

“The findings of the IPCC reports were developed in advance and furthered by a careful selection from whatever material could be found to support them. In some cases, supporting material was developed or fabricated where none could otherwise be located. As such, these findings may not necessarily reflect the true state of scientific understanding. Use at your own risk.”

A large collection of observations are indicating that our forecasts seem to be erring on the high side (notice I didn’t say that observations suggest that climate change wasn’t occurring, but that they suggest that the projections of climate change are too extreme). As such, I suggested that we ought not rush headlong into efforts aimed at attempting to restrict carbon dioxide emissions for the sake of trying to alter the course of future climate, considering that a) the future course of climate doesn’t seem to be all that bad, and b) that any impact that we may make would likely be minimal.

Here is an excerpt:

There’s a certain urgency these days to take action to mitigate climate change. World leaders assembled last month at the U.N. conference in Copenhagen to try to forge a global plan aimed to reduce carbon dioxide emissions. Back home, Congress, the EPA, and individual states (including Minnesota) are considering their own plans to do the same. All in an effort to steer the Earth’s climate in a direction other than the one in which it is projected to be heading.

But what if the climate projections are wrong? What if the earth’s climate isn’t plotting a course of death and destruction? Would it still make sense to restrict the kinds of energy we use even if it has little impact on the climate and/or future climate change was benign or possibly beneficial (for example, longer growing seasons, more precipitation)? . . . .

But many people respond that when it comes to climate change the “science is settled” — human emissions of carbon dioxide, primarily as a result from burning fossil fuels such as oil, coal and natural gas, are leading to catastrophic global warming. That without intervention, the list of impending disasters is long, including stronger hurricanes, rapid sea-level rise, widespread species extinctions, more intense heat waves, more frequent severe weather, and increasing droughts and floods as the Earth’s average temperature rises ever faster.

Recent events, however, conspire against these certainties.

Global hurricane activity has been near a half-century low, the current rate of sea-level rise is modest, averaging only about one foot per 100 years, fewer Americans are dying from heat waves, fatalities from tornadoes in the U.S. are declining (the 2009 total was the lowest in more than two decades), and Minnesota and much of the upper Midwest had one of their coldest summers on record. Most importantly, the pace of global warming has dramatically slowed in recent years, even in the face of rocketing global carbon dioxide emissions.

Collectively, this suggests a need to re-examine the inner workings of our current climate models and our expectations of climate change. The din of the alarm bells should be quelled. . . .  

It boils down to this: Current climate models overestimate the amount of warming we should expect from our carbon dioxide emissions, and thus actions aimed at limiting carbon dioxide emissions will have less of an impact on climate than is anticipated. In other words, we’ll be going through a lot of effort for little result — if mitigating climate change is the name of the game.

For the complete article, please visit the Pioneer Press Opinions page and my article We’re warming. But not so fast.

Editor note: On November 10, 2009 Mr. Green testifedbefore the Senate Committee on Finance about global warming. During the course of his testimony, an obviously agitated Senator John Kerry (D-Mass.) challenged Ken on different aspects of the climate debate. His responses are printed here. [Part II of this series is tomorrow.]

1. Not One Peer-Reviewed Paper Contradicts the “Consensus” View of the Climate Crisis
Sen. Kerry asserted that not one peer-reviewed paper contradicts the “consensus” view that greenhouse gas emissions will cause devastating consequences, and that we must limit their emissions radically to avoid the maximum “consensus” value of two degrees Celsius, which Kerry claimed was the point at which catastrophic damage would occur to the Earth’s climate. I offered to provide several.

Perhaps the central issue in climate science involves estimates of the sensitivity of the climate to anthropogenic greenhouse gas emissions. Sensitivity refers to just how much warming results from an increased concentration of greenhouse gases in the atmosphere. The following papers demonstrate that the climate’s sensitivity to greenhouse gases is considerably lower than the Intergovernmental Panel on Climate Change (IPCC) claims—so much lower, in fact, that the warming we would expect from doubling the amount of CO₂ in the atmosphere would be quite modest (well below two degrees Celsius) and offer very little risk. Do these papers truly reflect the reality of how the climate works? Perhaps they do, perhaps they do not, but it cannot be argued that they do not exist.

In a recently published article, Richard S. Lindzen and Yong-Sang Choi use data from NASA’s Earth Radiation Budget Experiment to assess the climate’s sensitivity to greenhouse gases. In this article, they demonstrate empirically that the climate sensitivity to a doubling of greenhouse gases is only about 0.5 degrees Celsius, one-sixth of the IPCC estimate of 3 degrees Celsius.

Another study by Roy W. Spencer and William D. Braswell also examines the data from NASA’s CERES satellites. It concludes that “eight years of the latest NASA satellite measurements of variations in both the Earth’s radiative budget, and in lower atmospheric temperature, suggest two important conclusions related to the global warming issue. The first is that the sensitivity of the climate system is much lower than the IPCC climate models suggest; that is, the climate system is dominated by negative feedbacks.” Spencer and Braswell also conclude that “taken together, these results suggest that the IPCC’s claim that global warming is mostly man-made is, at best, premature.”

A study by Nicola Scafetta and Richard C. Wilson examines data regarding changes in total solar irradiance (TSI), concluding: “This finding has evident repercussions for climate change and solar physics. Increasing TSI between 1980 and 2000 could have contributed significantly to global warming during the last three decades. . . . Current climate models . . . have assumed that the TSI did not vary significantly during the last 30 years and have therefore underestimated the solar contribution and overestimated the anthropogenic contribution to global warming.” If the warming of the last three decades has been driven by increases in solar output, it cannot also have been driven by human greenhouse gas emissions. This suggests that anthropogenic greenhouse gases have a low sensitivity value.

After studying satellite and radiosonde (weather balloon) data, John D. McLean, Chris R. deFreitas, and Robert M. Carter concluded that ocean patterns dominate climate change in the tropics. They write, “Overall the results suggest that the Southern Oscillation exercises a consistently dominant influence on mean global temperature, with a maximum effect in the tropics, except for periods when equatorial volcanism causes ad hoc cooling. That mean global tropospheric temperature has for the last 50 years fallen and risen in close accord with the SOI [Southern Oscillation Index] of 5–7 months earlier shows the potential of natural forcing mechanisms to account for most of the temperature variation.”

In another study, Petr Chylek and Ulrike Lohmann “use the temperature, carbon dioxide, methane, and dust concentration record from the Vostok ice core to deduce the aerosol radiative forcing during the Last Glacial Maximum to Holocene transition and the climate sensitivity.  Their research “suggests a 95% likelihood of warming between 1.3 and 2.3 K due to doubling of atmospheric concentration of CO₂.” (A degree Kelvin [K] is equal to a degree Celsius [C].) These values are considerably lower than the sensitivity values estimated by the IPCC.

In another study the authors use satellite and surface temperature observations to study the effect of aerosols on climate and to examine climate sensitivity. They find “that the climate sensitivity is reduced by at least a factor of 2 when direct and indirect effects of decreasing aerosols are included, compared to the case where the radiative forcing is ascribed only to increases in atmospheric concentrations of carbon dioxide.”

Sherwood B. Idso reviews various “natural experiments” that can reveal how sensitive the climate is to increasing concentrations of greenhouse gases, and concludes: “Over the course of the past 2 decades, I have analyzed a number of natural phenomena that reveal how Earth’s near-surface air temperature responds to surface radiative perturbations. These studies all suggest that a 300 to 600 ppm [parts per million] doubling of the atmosphere’s CO₂ concentration could raise the planet’s mean surface air temperature by only about 0.4°C. Even this modicum of warming may never be realized, however, for it could be negated by a number of planetary cooling forces that are intensified by warmer temperatures and by the strengthening of biological processes that are enhanced by the same rise in atmospheric CO₂ concentration that drives the warming. Several of these cooling forces have individually been estimated to be of equivalent magnitude, but of opposite sign, to the typically predicted greenhouse effect of a doubling of the air’s CO₂ content, which suggests to me that little net temperature change will ultimately result from the ongoing buildup of CO₂ in Earth’s atmosphere.”

Many other studies challenging various elements of the “consensus” that anthropogenic greenhouse gases are causing, or will cause, catastrophic climate change can be found at the website www.populartechnology.net, which boasts 450 peer-reviewed publications challenging different elements of the “climate crisis” paradigm which both Kerry and former vice president Al Gore whole-heartedly endorse.

2. Ice-Free Arctic by 2013

When I mentioned that the claims that we would see an ice-free-Arctic by 2013 had been withdrawn, Senator Kerry asked for documentation. I provided it. The outgoing head of Greenpeace, Gerd Leipold, retracted his claim that the Arctic would be ice-free by 2030 in an interview with the BBC. In the video, Leipold says, “I don’t think it will be melting by 2030. . . . That may have been a mistake.” However, there is also considerable controversy over the claim of an ice-free Arctic by 2013, as can be seen in the following articles:

In an article by Jonathan Amos, other Arctic ice researchers refute the assertion that an ice-free arctic is likely by 2013. The article quotes Mark Serreze, a research scientist with the U.S. National Snow and Ice Data Center, saying, “A few years ago, even I was thinking 2050, 2070, out beyond the year 2100, because that’s what our models were telling us. But as we’ve seen, the models aren’t fast enough right now; we are losing ice at a much more rapid rate. My thinking on this is that 2030 is not an unreasonable date to be thinking of.” Serreze also told the BBC that Wieslaw Maslowski, the climate scientist who announced that arctic summers could be ice free by 2013, “is probably a little aggressive in his projections, simply because the luck of the draw means natural variability can kick in to give you a few years in which the ice loss is a little less than you’ve had in previous years.”

An article by David Adam quotes Vicky Pope, the head of climate change advice at the British Met Office Hadley Centre, as saying that “there is little evidence to support claims that Arctic ice has reached a tipping point and could disappear within a decade or so, as some reports have suggested.” The article states that “summer ice extent in the Arctic, formed by frozen sea water, has collapsed in recent years,” and notes that the amount of ice in September of last year was 34 percent lower than the average amount of ice present since satellite measurements began in 1979. Pope says, “The record-breaking losses in the past couple of years could easily be due to natural fluctuations in the weather, with summer ice increasing again over the next few years.” She goes on to say, “It is easy for scientists to grab attention by linking climate change to the latest extreme weather event or apocalyptic prediction. But in doing so, the public perception of climate change can be distorted. The reality is that extreme events arise when natural variations in the weather and climate combine with long-term climate change.”

According to the British Met Office, the 2007 Arctic ice-melt was an anomaly unrelated to climate change. The article says, “Modeling of Arctic sea ice by the Met Office Hadley Centre climate model shows that ice invariably recovers from extreme events, and that the long-term trend of reduction is robust—with the first ice-free summer expected to occur between 2060 and 2080. It is unlikely that the Arctic will experience ice-free summers by 2020.”

Note: A PDF of this article in its original format can be found here.

Editor’s Note: Jim Manzi is a Senior Fellow at the Manhattan Institute, and blogs at both National Review’s The Corner and at The American Scene.

It is amusing to watch advocates of rapid, aggressive carbon dioxide emissions reduction, when confronted with the plain facts of the consensus scientific projections for climate change and its associated damages, move from “science says we must do this or die” to “well, actually, the science is pretty uncertain, so it’s possible that we might die,” and then proceed to some restatement of Pascal’s Wager.

Friedman’s Throw

Tom Friedman’s recent New York Times column is a perfect illustration of this logic.  I’ll quote him at length, before demonstrating that his emission-cuts-as-insurance analogy breaks down once you plug in actual numbers:

This is not complicated. We know that our planet is enveloped in a blanket of greenhouse gases that keep the Earth at a comfortable temperature. As we pump more carbon-dioxide and other greenhouse gases into that blanket from cars, buildings, agriculture, forests and industry, more heat gets trapped.

What we don’t know, because the climate system is so complex, is what other factors might over time compensate for that man-driven warming, or how rapidly temperatures might rise, melt more ice and raise sea levels. It’s all a game of odds. We’ve never been here before. We just know two things: one, the CO2 we put into the atmosphere stays there for many years, so it is “irreversible” in real-time (barring some feat of geo-engineering); and two, that CO2 buildup has the potential to unleash “catastrophic” warming.

When I see a problem that has even a 1 percent probability of occurring and is “irreversible” and potentially “catastrophic,” I buy insurance. That is what taking climate change seriously is all about.

Computing the Odds

The United Nations Intergovernmental Panel on Climate Change (IPCC) is the leading bookie for this game.  The current IPCC consensus forecast is that, under fairly reasonable assumptions for world population and economic growth, global temperatures will rise by about 3°C by the year 2100 (Table SPM.3). Also according to the IPCC, a 4°C increase in temperatures would cause total estimated economic losses of 1–5 percent of global GDP (page 17). By implication, if we were at 3°C of warming at the end of this century, we would be well into the 22^nd century before we reached a 4°C rise, with this associated level of cost.This is the central problem for advocates of rapid, aggressive emissions reductions. Despite the rhetoric, the best available estimate of the damage we face from unconstrained global warming is not “global destruction,” but is instead costs on the order of 3 percent of global GDP in a much wealthier world well over a hundred years from now.

It should not, therefore, be surprising that formal efforts to weigh the near-term costs of emissions abatement against the long-term benefits from avoided global warming show few net benefits, even in theory. According to the modeling group led by William Nordhaus, a Yale professor widely considered to be the world’s leading expert on this kind of assessment, an optimally designed and implemented global carbon tax would provide an expected net benefit of around $3 trillion, or about 0.2 percent of the present value of global GDP over the next several centuries (page 84). While not everything that matters can be measured by money, this certainly provides a different perspective than the “Earth in the balance” rhetoric would suggest.

Now, in absolute terms, $3 trillion is normally thought of as an amount of money that’s worth pursuing. So why shouldn’t we implement such a tax?

Now to the Real World

To understand why, let’s move from the world of academic model-building to the real world of geostrategic competition and domestic politics. To realize this gain of $3 trillion, we would have to agree to, and enforce, a global, harmonized tax on all significant uses of carbon and other greenhouse gases in any material form. This would require the agreement of — just to take a few examples — the Parliament of India, the Brazilian National Congress, the Chinese Politburo, Vladimir Putin, John Dingell, and the U.S. ethanol lobby. Each of these entities and individuals has been known to elevate narrow, sectarian interests above the comprehensive good of all mankind through all time, to put it mildly.

All this aside, let’s imagine we actually could negotiate such a binding agreement. Isn’t it possible that all the side deals that would be required to get this done would create enough economic drag to more than offset the benefit of 0.2 percent of present value of global output? Our track record in closing and implementing such deals as the Kyoto Protocol, or even the current round of WTO negotiation — which, remember, is supposed to make the signatories richer — shouldn’t inspire much confidence that the theoretical net benefits will outweigh the costs created by the agreement. Indeed, today we are not even considering an actual U.S. carbon tax, which is preferred by almost all academic economists for this purpose, but instead a cap-and-trade system (i.e., emissions rationing) because it is more politically palatable to hide the costs to consumers this way. Yet even the staggering list of side-deals, offsets, special auctions, and so forth that were added to the ACES cap-and-trade bill were not enough to build a winning congressional coalition within this inefficient framework.

Further, even if we got to an agreement de jure, we would then have to enforce a set of global laws for hundreds of years that would run directly contrary to the narrow self-interest of most people currently alive on the planet. How likely do you think a rural Chinese official would be to enforce the rules on a local coal-fired power plant? These bottom-up pressures would likely render such an agreement a dead letter, or at least make it in effect a tax applicable only to the law-abiding developed countries that represent an ever-shrinking share of global carbon emissions.

A Summing Up

In summary, then, the best available models indicate that

1) global warming is a problem that is expected to have only a limited impact on the world economy and

2) it is economically rational only to reduce slightly this marginal impact through global carbon taxes.

Further, practical knowledge of the world indicates that

1) such a global carbon-tax regime would be very unlikely ever to be implemented, and

2) even if it were implemented, the theoretical benefits it might create would almost certainly be more than offset by the economic drag such a regime would produce. Other than that, it sounds like a great idea.  If our scientific forecasts turn out to be precisely correct, one could not rationally justify rapid, aggressive reductions in CO₂.

But climate models are, at a minimum, non-validated. Predicting the cost impact of various potential warming scenarios requires us to concatenate these climate predictions with economic models that predict the cost impact of these predicted temperature changes on the economy in the 21^st, 22^nd, and 23^rd centuries. It is hubris to imagine that these can guarantee accuracy, and impossible to validate such a claim in any event.  Exactly as Friedman says, “it’s a game of odds”.

But What About Extreme “Tail” Events?

Now, climate and economics modelers aren’t idiots, so it’s not like this hasn’t occurred to them prior to reading Friedman’s column. Competent modelers don’t assume only the most likely case, but build probability distributions for levels of warming and associated economic impacts (e.g., there is a 5 percent chance of 4.5°C warming, a 10 percent chance of 4.0°C warming, and so on).  The IPCC reports include extensive analyses of this handicapping, and in fact publish these probability distributions.  If you odds-adjust the forecasts to reflect that actual warming might be worse (or not as bad) as the expected case, you get just about exactly the same expected value of damages.  The economic calculations that comprise, for example, the analysis by William Nordhaus that I referenced earlier are executed in just this manner. In other words, this is a “game of odds” in which rapid, aggressive emissions reduction is a sucker bet.

What this of course leaves open is the inherently unquantifiable possibility that our probability distribution itself is wrong.  In econo-speak, there is always residual uncertainty, rather than mere risk, in any prediction.  (Note in passing that we have now moved all the way from “science says we will be destroyed” to “science says we might be destroyed” all the way to “the science might be wrong”.)

All that said, this is not an irrational concern.  The sophisticated version of this argument has been presented by Harvard economics professor Martin Weitzman.  Professor Weitzman’s reasoning on this topic is subtle and technically ingenious.  In my opinion, it is the most rigorous existing argument for a carbon tax or similar emissions reduction scheme.  Addressing it in detail is beyond the scope of this post, but I have previously responded to a slightly earlier version of it in a long online article.  Alternatively, you can watch a video of Professor Weitzman presenting his paper, and then my response to it in the exact same room a few months later.  I encourage anybody who is serious about the climate change debate to understand Weitzman’s logic in detail.

In very short form (recognizing that I will write somewhat loosely for purposes of brevity in this setting), Weitzman’s central claim is that the probability distribution of potential losses from global warming is “fat-tailed”, or includes high enough odds of very large amounts of warming (20⁰C or more) to justify taking expensive action now to avoid these low probability / high severity risks.

The big problem with this argument, of course, is that the IPCC has already developed probability distributions for potential warming that include no measurable probability for warming anywhere near this level for any marker scenario.  See, for example, WG1 SPM Figure SPM.6.  Even the scale on these charts — never mind actual predictions for the high end of the probability distributions — doesn’t go past 8⁰C.  That is, the best available estimates for these probability distributions are not fat-tailed in the sense that Weitzman means it.

Now, one can responsibly question the probability distributions developed by the IPCC.  A modest version of this is simply to recognize that we are not certain that they are correct.  But this is just a sophisticated restatement of one predicate of the Precautionary Principle.  Of course, this is true in principle for all probability distributions, and therefore for all risks.  As Weitzman himself clearly recognizes, in order for him to distinguish climate change dangers from other dangers in this matter, he must therefore show not only that it is possible that the true probability distribution of potential levels of warming is actually much worse than believed by the IPCC, but that a reasonable observer should accept it as likely that this is the case.  In order to do this, he is forced to do his own armchair climate science, and argue (as he does explicitly in the paper) that he has developed a superior probability distribution for expected levels of warming than the ones the world climate-modeling community has developed and published.  As noted above, this probability distribution is radically more aggressive than anything you will find in any IPCC Assessment Report.  I don’t think that it is credible to accept Professor Weitzman’s climate science in place of the IPCC’s.

You Can’t Prove a Negative

The only real argument for rapid, aggressive emissions abatement, then, boils down to the point that you can’t prove a negative. If it turns out that even the outer edge of the probability distribution of our predictions for global-warming impacts is enormously conservative, and disaster looms if we don’t change our ways radically and this instant, then we really should start shutting down power plants and confiscating cars tomorrow morning. We have no good evidence that such a disaster scenario is imminent, but nobody can conceivably prove it to be impossible. Once you get past the table-pounding, any rationale for rapid emissions abatement that confronts the facts in evidence is really a more or less sophisticated restatement of the Precautionary Principle: the somewhat grandiosely named idea that the downside possibilities are so bad that we should pay almost any price to avoid almost any chance of their occurrence.  This is Friedman’s update to Pascal’s wager, though he throws around the pseudo-quantification of “1%”, even though the scientific consensus he waves at doesn’t quantify anything like a 1% chance of what he describes.

But to force massive change in the economy based on such a fear is to get lost in the hothouse world of single-issue advocates, and become myopic about risk. We face lots of other unquantifiable threats of at least comparable realism and severity. A regional nuclear war in Central Asia, a global pandemic triggered by a modified version of HIV, or a rogue state weaponizing genetic engineering technology all come immediately to mind. Any of these could kill hundreds of millions of people. Scare stories are meant to be frightening, but we shouldn’t become paralyzed by them.

What Then Should Be Done?

In the face of massive uncertainty on multiple fronts the best strategy is almost always to hedge your bets and keep your options open. Wealth and technology are raw materials for options. The loss of economic and technological development that would be required to eliminate literally all theorized climate change risk would cripple our ability to deal with virtually every other foreseeable and unforeseeable risk, not to mention our ability to lead productive and interesting lives in the meantime. The Precautionary Principle is a bottomless well of anxieties, but our resources are finite — to extend Friedman’s metaphor, it’s possible to buy so much flood insurance that you can’t afford fire insurance.

Hedging against the risk to future generations of potential unanticipated impacts from global warming is a legitimate job for the U.S. government. Ideally, it would be tackled by the governments of the small number of countries with a sophisticated technology development capability acting in some kind of coordinated fashion. A massive carbon tax, a cap-and-trade rationing system, and the attempt to use the government to control the evolution of the energy sector of the economy are all billed as prudent reactions to this risk, but each is the opposite: an impractical, panicky reaction unworthy of a serious government.

Editor’s note: Bradley’s op-ed appeared in the December 8th Washington Times under the title “Alarmists Cold-Shoulder Facts”)

Facts are awfully stubborn things. And global-warming alarmists—who generally don’t let facts get in the way of a good, agenda-driven argument—recently lost a key ally in the run-up to the U.N. global-warming pep rally opening today in Copenhagen. They lost actual data supporting their claims.

In defiant acts of desperation, many out-of-the-mainstream environmental alarmists quickly moved to plan B. Some cite the current El Niño—a natural climate variation—warning of “record” high temperatures just on the horizon.

Others continue to trumpet “studies” that paint terrifying environmental fairy tales if world governments do not immediately criminalize carbon, ban fossil fuels, and ration energy.

But these tactics are not new. Paul Ehrlich’s “population bomb” of the 1960s predicted food riots in the United States and around the world. Today, obesity is a bigger problem.

Remember the Club of Rome’s 1972 prediction of resource exhaustion? Fifty-seven predictions were made regarding 19 minerals, and all either have been proved false or will be.

Perhaps most hypocritical is the global-cooling scare promoted by, among others, Mr. Obama’s science czar, John Holdren. Today, Mr. Holdren says a billion people may perish from global warming by 2020.

It’s understandable why public opinion continues to squarely reject the apocalyptic vision of climate change. In Washington, pragmatic politicians of both parties balk at even watered-down proposals to cap greenhouse gas (GHG) emissions that will bring higher energy costs and more government control.

There simply is not an appetite for this social-engineering project. And despite the dire warnings of an intellectual cadre, the public is getting it right. The Earth’s average temperature is virtually unchanged from a dozen years ago—a result not predicted by climate modelers or activists.

The rate of sea-level rise has slowed to a crawl, throwing cold water on ice-melting scares. Global hurricane activity is near a 30-year low. Fatalities from tornadoes across the United States this year are on course to be the lowest in more than a decade. (Yes, some scientists link global warming to tornadoes.) In 2009, much of the Midwest and Northeast shivered through the coldest summer in recent memory.

While climate models are supposed to be snapshots of the Earth’s real climate, the mismatch between observed and modeled climate behavior shows that even the best models are not accurate and are likely overestimating outcomes. Gerald North, a Texas A&M atmospheric sciences and oceanography professor, estimates that climate models overestimate warming by roughly 50 percent.

Though climate models have proved to be an obvious inconvenient truth, alarmists continue to ignore this elephant in the room.

In fact, this is buried on Page 805 of the latest assessment from the Intergovernmental Panel on Climate Change (IPCC): “The set of available models may share fundamental inadequacies, the effects of which cannot be quantified.” It’s telling that this was not stated forthrightly in the assessment’s summary.

Science should trump politics, social engineering and agendas. And public opinion increasingly reflects this, as the case against climate alarmism continues to grow.

But there is a crisis that international leaders need to address at Copenhagen. The real planetary emergency is that 1.5 billion people do not have access to modern, affordable, and reliable forms of energy or the electricity they produce.

The poorest and most underprivileged people in the world would benefit most from coal furnaces, natural gas plants, and other modern resources that our carbon-based economy and infrastructure help generate.

Some environmental elitists may say: “Let them use solar panels.” But the moral imperative of the 21st century is to liberate the master resource of energy from the politics of these reactionary enemies of democratizing progress, prosperity, and quality of life.

 Appendix: Letter to Houston Chronicle (December 11) in Response to Climategate Op-Ed

The Chronicle’s lengthy editorial, “No denying” makes three major points, one sound and the two unsound. Yes, the scientific method requires openness and honesty, something that Climategate has revealed to be absent among top U.S. and international climate scientists who were behind the influential United Nations/Intergovernmental Panel on Climate Change climate reports.

But the editorial goes on to state that the climate alarm is “overwhelmingly persuasive” and that NASA scientist James Hansen, the leading alarmist scientist in the world, “is not an ideologue.”

A number of climate-change metrics have become less alarming over time, ranging from global temperature to hurricanes. Climate models (including that of Hansen at NASA’s Goddard Institute) have demonstrably overestimated climate sensitivity to greenhouse gas. But rather than hedge his bets and show humility toward the very complex system he is trying to model, Hansen has called for oil industry executives to be prosecuted and for civil disobedience at coal facilities.

Suffice it to say that Climategate is just the tip of the iceberg of misbehaving mainstream climate scientists whose personal agendas and lack of humility have misled not only themselves but many others. We all deserve better.

Robert L. Bradley is the chief executive officer and founder of the Institute for Energy Research in Houston.