Posted by: bmeverett | March 20, 2014

A Reply to Greg Craven (Part 1)

I recently posted some comments on a Youtube video by Greg Craven, a high school teacher in Oregon (“The Kid’s Logic”, February 21). I received a nice response from Greg asking for comments on his book “What’s the Worst That Could Happen? A Rational Response to the Climate Change Debate.” I have now read the book and offer the following open letter to Greg. If Greg elects to reply, I promise to post his comments in full. Here goes.

Dear Greg:

I’ve finished reading your book and appreciate the opportunity to comment. First, some positive remarks. I fully agree that the climate debate has become a shouting match, and I would like to make common cause with people like you who want to understand the issue and discuss the problem rationally and reasonably. Second, you’re a great writer, and I really like your style and humor. By the way, I bought your book, rather than finding a free pdf on the web. Please spend the money wisely.

Now for the negative part. Your argument is still completely wrong. Let’s accept for a moment that your 2 X 2 matrix is valid, even if oversimplified. I’ll use your terminology of “warmist” vs “skeptical”. In your original video, you claimed that the decision on climate change action did not rely on determining whether the “warmist” view is true. You now acknowledge that this approach is incorrect and spend most of your book time trying to convince the reader that the warmist argument is correct. You’ve failed to make this case, at least to me.

Let me offer my comments in three batches over the next three weeks: science, economics and general. Let’s start with science.
The key question for the climate change issue is how lay people (also known as voters) can come to understand a complex scientific issue that carries major implications for their living standards. You offer a structure in which we should essentially see climate change as a debate in which scientific propositions are being offered by various people, and you then suggest that we organize these people into a credibility spectrum.

The upper left of your spectrum consists of high-credibility people in the warmist camp, and the upper right is high-credibility skeptics. You find lots of people on the left side and nothing comparable on the right. This is in essence your argument, which I believe is flawed. The credibility of the scientific community depends on open inquiry and the willingness of scientists to evaluate empirical evidence on its merits. These conditions are met for most scientific questions, but not for climate change.

Most scientists are academics and live in university communities. Universities used to be repositories of scholarship and were fierce defenders of the rules of open inquiry, especially the scientific method. Many academic institutions have evolved, however, into political advocacy organizations that see their role as changing the world for the better, an approach sometimes known as the “social justice” movement. There’s nothing at all wrong with scientists and other university faculty expressing political opinions and exercising their rights as citizens. The problem comes when the search for truth is subordinated to the construction of effective debating points. The social justice movement has come to define certain issues, particularly climate change, “diversity,” “sexual assault awareness”, gay marriage, immigration, affirmative action and abortion as moral crusades rather than subjects for legitimate debate. Solidarity trumps open inquiry, and opposing views are regarded not as incorrect logic but as character flaws.

This approach to climate change was articulated openly and honestly in 1989 by Stephen Schneider, Professor of Environmental Biology and Global Change at Stanford:

On the one hand, as scientists we are ethically bound to the scientific method, in effect promising to tell the truth, the whole truth, and nothing but — which means that we must include all the doubts, the caveats, the ifs, ands, and buts. On the other hand, we are not just scientists but human beings as well. And like most people we’d like to see the world a better place, which in this context translates into our working to reduce the risk of potentially disastrous climatic change. To do that we need to get some broad based support, to capture the public’s imagination. That, of course, entails getting loads of media coverage. So we have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we might have. This ‘double ethical bind’ we frequently find ourselves in cannot be solved by any formula. Each of us has to decide what the right balance is between being effective and being honest. I hope that means being both.

Climate change orthodoxy has been institutionalized on many campuses. I doubt you could find a university with an “Office of String Theory Advancement” or an “Office of Higgs Boson Promotion”, but you can find many “Offices of Sustainability”. In fact, a Google search of “university office of sustainability” gets over 91 million hits. If you ask the university sustainability directors what they are doing, they will happily talk about reducing the campus’s carbon footprint by maximizing the use of renewable energy, cutting energy consumption and improving environmental literacy. A core part of their mission is to teach the University community that the warmist view is an established fact and that advancing the warmist agenda is a matter of personal responsibility, not a subject for scientific inquiry. Students are told that reducing carbon and lobbying for carbon mitigation is a social service activity, akin to feeding the homeless. Tufts University, where I teach, has an Institute for the Environment, which includes a program called “Climate Change, Climate Justice”. Here’s its mission statement:

As an enormous body of research makes explicitly clear, people of color, women, and especially the poor will bear the brunt of the catastrophic effects of climate change globally. Climate change is without doubt the biggest social justice issue of this century as it is estimated that many millions of people, primarily in poor countries, are likely to face displacement, disease, war and death as a result of climate change caused primarily by rich Western countries.

Does that sound like an invitation to open discussion? When the community in which you live and work establishes and constantly reinforces an official orthodoxy on a critical issue, the effect is to chill speech and limit debate.

Under these circumstances, you should not assume that what you are reading and hearing represents a full spectrum of views. When I discuss climate change in my class, my warmist students push back hard. I’m glad they do, since we can have a spirited debate. Many other students, however, tell me privately in office hours that they share my concerns about climate change, but don’t dare express these views publicly for fear of provoking hostility or ridicule from classmates and faculty.

I have no data, but do wonder about (1) how many skeptical scientists keep quiet for fear of the consequences, (2) how many scientists choose to research less controversial topics in order to retain full freedom of expression, (3) how many skeptical young scientists are not hired because their views are unacceptable to their peers and (4) how many smart young people pick fields other than climate science where they are free to pursue open inquiry safely.

Greg, you place a great deal of weight on scientific bodies, such as the UN Intergovernmental Panel on Climate Change (IPCC). Professor Schneider’s view, however, has begun to permeate the bodies you rely on for honest and objective science. Forty years ago, we could have easily distinguished, for example, between the American Physical Association (APS) and the Union of Concerned Scientists (UCS). The APS was founded to advance knowledge of physics, while the UCS was established to advocate for certain government policies, initially nuclear disarmament and later climate change. The members of the UCS are distinguished scientists, but their mission is to win political debates using the credibility of their members as a tool. They are in effect salesmen. There’s nothing wrong with this, provided we all understand what they are doing. In the last 15-20 years, the APS has evolved from a scientific professional organization to a political advocacy group akin to the UCS. If you don’t believe me, check their climate change statement at Their position is purely political, not scientific, and some members of the APS objected on those grounds. The APS may be correct, but they now resemble the UCS rather than a professional physics society.

This problem is amplified in the IPCC. Hundreds of scientists participate in the detailed work of the IPCC, but only a handful write the critical “Summary for Policy-Makers”. Many of these people are avowed warmists who see their role as making the strongest possible case for carbon mitigation. They may be right, but they are not a scientific body.

You also rely on the peer review process to filter out good ideas from the noise. The peer review process itself has been badly damaged by the climate debate. When the universe of potential writers and reviewers consists primarily of warmist scientists with a social justice attitude, the process will filter for politics, not science. If you doubt the seriousness of this problem, review the infamous emails from the 2009-2010 “climategate” scandal, in which prominent warmist scientists discuss how to subvert peer review to make sure that skeptical articles do not appear.

You also give credibility to corporations who express support for some or all of the warmist agenda on the grounds that the interests of these organizations should incline them toward the skeptical camp. Therefore, their support for warmism must be sincere. I believe you are misreading what’s happening here. During the run-up to the Kyoto Protocol in 1997, ExxonMobil made a series of strong public statements, warning that (a) climate science is insufficient to support scary climate scenarios and (2) the economic costs of carbon mitigation are very high. I can tell you from my personal experience as an ExxonMobil executive that these positions were sincerely held by the management of the corporation, particularly our CEO Lee Raymond. Inside ExxonMobil, we regarded these statements as thoughtful and constructive, but they generated a massive attack by environmental groups, such as Greenpeace. This pushback did some damage to the corporation’s public image, which wasn’t all that great to begin with after the Valdez oil spill of 1989. When Lee Raymond retired in 2005, the new management reevaluated the Corporation’s position on climate change and concluded not that the corporation’s position was wrong, but that the pain of public engagement on the issue wasn’t worth the gain. ExxonMobil never endorsed the warmist position, but simply stopped talking about climate science and politics. Opinion research suggests that the public assumes that anything oil companies say is self-serving and that the public just wants to know that corporations are behaving responsibly. As a result, ExxonMobil chose simply to say that long-term reduction of carbon emissions would be a good idea, provided carbon mitigation was balanced against other priorities, such as economic growth. The Corporation would do its part by improving its energy efficiency. You can find the Corporation’s full statement at Not much here to support the warmist agenda.

Many other corporations watched ExxonMobil get beaten up and got the message. Shell and BP, in particular, took public positions much closer to the warmist view. Many of my colleagues at these two companies told me privately that their managements agreed with ExxonMobil on the substance of climate science and economics, but chose to avoid the flak associated with stating that position publicly. This “positioning by focus group” may be sensible corporate strategy, but has nothing to do with the views the business community really holds on climate science. Other companies, such as General Electric, manufacture renewable energy equipment and are happy to encourage the federal government to subsidize their products.

As a final comment, you place a great deal of importance on the views of distinguished individual scientists, such as James Hansen, one of the icons of the warmist camp. A person like Dr. Hansen, who chains himself to the White House fence and demands that oil company executives be tried for crimes against humanity, may be a brilliant scientist and he may even be right, but he cannot be regarded as a credible interpreter of balanced and impartial science. Dr. Hansen has staked his entire professional reputation on the validity of the extreme warmist position and would look like a complete fool if the skeptical position proved to be correct. Many skeptical scientists suffer from the same problem. Dr. Pat Michaels, for example, is a brilliant scientist with impeccable credentials, but he has staked his reputation on the validity of the skeptical camp. Both of these men chose to change their role from scientist to political advocate. You cannot be both.

The problem then, Greg, is that nobody has any real credibility here. Virtually everyone who is knowledgeable on climate science has either chosen sides in this debate or is sitting it out. Your credibility spectrum may be an excellent approach to evaluating the state of play of some scientific controversies, but climate change is simply too politicized. We need to find some other way.

We are in a position analogous to jurors in a complex technical trial who have listened to the testimony of paid experts put on the witness stand by the plaintiff and the defendant. All are acknowledged experts in their fields, and they all sound convincing, but all have an obvious conflict of interest. The jurors have no choice in this situation but to look at the merits of the arguments, not the credibility of the people making the arguments.

So, setting aside the individuals involved, what are we arguing about? Since the warmists are arguing for fundamental changes in our economic and political life (more on this in the next installment), the burden of proof is on them. Here, ladies and gentlemen of the jury are the arguments for the prosecution.

First, the atmosphere has been warming over the last 100 years or so. Despite some methodological issues, the science on this point seems pretty compelling. Measured surface temperatures, confirmed by later satellite observations, show an increase of about 1° C this past century. This point goes to the warmists.

Second, this temperature increase is unprecedented in known history. Not so fast here. Several prominent warmists, notably Prof. Michael Mann of Penn State, have constructed a historical time series, known colloquially as the “hockey stick” that purports to show relatively flat temperatures over the past 1,000 years or so followed by a sharp uptick over the last century. The analysis is based on combining thermometer readings over the last 100-150 years with indirect historical data series based on tree rings, coral, ice cores and other parameters. There are many methodological problems with this approach, and I am not in a position to sort them out. It is clear, however, that this analysis is highly controversial, despite the vigorous defense of the warmists. The verdict on this contention is “not proven”.

The third argument is that increased atmospheric carbon concentrations will cause temperature to increase. There is solid theoretical and empirical evidence for this contention, and the point goes clearly to the warmists. However, the direct effect of expected carbon emissions is likely to be relatively modest and would not produce the scary climate scenarios we are all familiar with.

The fourth, and most critical argument, is that climate feedback loops amplify rather than dampen the climate impacts of atmospheric carbon concentrations. Here, Greg, I think you have misinterpreted the IPCC work. You suggest in your book that the IPCC reports ignore the possible feedback loops in the climate system. In your view, this oversight creates a major risk that the temperature effects will be much higher than the IPCC scenarios suggest. In fact, all the climate models used in the IPCC studies already include positive feedback loops. The lowest IPCC scenarios show warming still above what we would expect from the direct effect of increased atmospheric carbon. This assumption actually skews the temperature analysis upward.

The IPCC acknowledges the large uncertainties here. The biggest uncertainty is the impact of warming on cloud formation. Clouds trap heat but they also reflect sunlight. The latest IPCC report (AR5) states, “The quantification of cloud and convective effects in models, and of aerosol–cloud interactions, continues to be a challenge. Climate models are incorporating more of the relevant processes than at the time of AR4, but confidence in the representation of these processes remains weak.” In reality, we don’t know whether the net effect of climate feedback loops is positive or negative, which creates a very wide range of possible outcomes, including scenarios in which increased carbon concentrations cause little if any long-term warming and scenarios in which modest climate warming is actually beneficial to humans. The IPCC does not properly acknowledge these more benign outcomes.

Positive climate feedback is an opinion, not a scientific conclusion. I don’t have the time or training to resolve this issue, but there is a theoretical argument that the feedback loops may be negative. As a scientist, Greg, you are undoubtedly familiar with Le Chatelier’s Principle, which states that “Any change in the status quo prompts an opposing reaction in the responding system.” In fact, the entire modern environmental debate is really about Le Chatelier’s Principle. Environmentalists tend to believe that natural systems are inherently fragile and prone to collapse if disturbed. Le Chatelier’s Principle suggests the opposite, i.e., that natural systems are robust and will compensate for disturbances. This is not to say that there are never adverse consequences when natural systems are disturbed, but they will tend to push back, restoring a new, if different equilibrium. In other words, Le Chatelier tells us to expect negative feedback loops. This by no means resolves the controversy, but it does suggest that the current IPCC assumptions may be too pessimistic rather than too optimistic as you suggest.

To wrap up this section, let me address one more issue: the track record of warmist predictions. I realize, Greg, that your book was published in 2008, so a lot has happened since then, but the prediction record of the warmists is just plain terrible. Every month through the 1990s, warmists like Al Gore trumpeted a new temperature record. Beginning in the late 1990s, however, a funny thing happened: the warming stopped. Climate scientists should have reevaluated the warmist conclusions to see whether they were still valid. Instead, the warmists frantically sought explanations that would preserve the warmist agenda, insisting that no matter what the data show, the warmist agenda must still be right. The warmists seem to have settled on aerosols – particulates that reflect sunlight causing an unanticipated cooling effect. This may be true, but it’s a classic case of “curve fitting” – structuring the data to meet the expected correlation – a no-no in statistical methodology.

What about the predictions of the severe consequences of warming? In your discussion of the supposedly high-credibility Association for the Advancement of Science (AAAS), you say “[In 2006] The association claimed that the pace of climate change has increased in recent years and said that ‘the intensification of droughts, heat waves, floods, fires and severe storms’ are ‘early warning signs of even more devastating damage to come, some of which will be irreversible’”. This claim has been repeated time and again by warmists and even by President Obama in his 2013 State of the Union address. The problem is that these statements are not factually correct. Severe storms, wildfires and droughts have shown no clear trend over the past 100 years. Wildfires, for example, are determined more by forest management practices than by climate and were far more severe in the US in the 1930s than they are today. For more on the severe storm fallacy, see my post “Hurricane Sandy and Climate Change” from November 13, 2012 at

In your book, you asked a very sensible question: What would it take to change your mind? I don’t know if all your highly credible warmists could answer that question, but I can. If the general circulation models the IPCC uses to predict climate effects could show any predictive ability, I would take them seriously. The problem is that, despite your contention, these models are unable to predict anything. Your contention that the warmists have a good track record is simply not true.

The warmists have failed to convince me that the scary scenarios are anything other than debating tools with no real science behind them. In my 2 X 2 matrix, the row for catastrophic climate change would be extremely thin, probably too thin to appear on the chart. The warmists will have to do much better.

P.S. Greg, you really shot your scientific argument in the foot with your comment that “… Peak Oil is also a certainty (or, as close as science can get to one) in our lifetimes”. I realize that a lot has happened since you wrote your book, but Peak Oil was always a highly controversial proposition. Although there have been some thoughtful proponents of this idea, including M. King Hubbert, Ken Deffeyes and Matt Simmons, very few people in the oil industry ever believed it. In fact, the oil industry has found more oil than it produced consistently for the past 150 years. To cite an example I use in my class, in 1980, global oil reserves were estimated by BP at 683 billion barrels. Since then, we have consumed approximately 829 billion barrels. How much do we have left? 1,669 billion barrels. Humans have been producing increasing amounts of copper for 5,000 years without hitting peak production. Why? Because technology can beat depletion over millennia. If this is your definition of scientific certainty, perhaps a rethink is in order.

I realize that this was an unusually long post, but Greg’s arguments deserve a thorough response. Next week, some comments on climate economics.



  1. *slow clap

    • Thanks, Anthony. Is a slow clap good or bad?

  2. haha it’s a good thing, usually reserved for when something profound or moving is said which results in a spontaneous urge to start clapping, which usually has a “wave” effect on the audience-not the types of applause used to bookend speakers or those extra special state of the union type claps

  3. I just watched Greg Craven’s video “One Guy With a Marker Just Made The Global Warming Debate Completely Obsolete.” He asks several times that if someone has a polite way to prove him wrong he will listen, however this is the only place so far that I have found where communicating with Mr. Craven might be possible.

    I would like to respond to Mr. Craven that he may need at least one more column. In this column, or more likely columns, one should consider “when we live.” Most likely any geologist will tell that we live in the Holocene Epoch, or presently 11,717 years since the end of the Younger Dryas Cold Interval. The end of the YD saw full interglacial conditions established.

    There are several obvious problems with 11,717 years to a geologist. First, only 1 interglacial in the past million years has lasted longer than about half a precession cycle. The precession cycle varies between 19 and 23k years. We are at the 23kyr part of that cycle now. 11,500 would be half a precession cycle and the Holocene this year is 11,717 years old.

    The debate about how long the present interglacial should last has been raging in the paleoclimate community for as long as the Global Warming debate, and it came from exactly the same data, the polar ice cores.

    In 2003 the debate intensified when well-known professor William Ruddiman published his Early Anthropogenic Hypothesis, which stated that the earth would have descended into the next ice age already were it not for anthropogenic climate impacts. So what is so ominous about that?

    Well, if GHGs are what have been preventing the next glacial inception, then quite obviously we should remove such a climate security blanket from the late Holocene atmosphere, put nature back on course, and enjoy the next 80-90kyr ice age. Just as obviously, this will require at least one more column.

    However, it might actually be a whole lot worse than we thought……

    You see paleoclimate research has moved forward quite some way in the last decade or so. We now know that the ends of the post-Mid Pleistocene Transition (MPT) interglacials are quite the wild climate ride down into the next glacial:

    Boettger, et al (Quaternary International 207 [2009] 137–144) abstract it:

    “The transition (MIS 5e/5d) from the Last Interglacial (Eemian, Mikulino) to the Early Last Glacial (Early Weichselian, Early Valdai) is marked by at least two warming events as observed in geochemical data on the lake sediment profiles of Central (Gro¨ bern, Neumark–Nord, Klinge) and of Eastern Europe (Ples).

    “The pronounced climate and environment instability during the interglacial/glacial transition could be consistent with the assumption that it is about a natural phenomenon, characteristic for transitional stages.”

    The obvious question here is what do Boettger et al 2009 mean by “two warming events”?

    And this is where it gets very ugly indeed. The Intergovernmental Panel on Climate Change (IPCC) Assessment Report 4 (2007) Figure 10.33 from page 821 of Chapter 10 shows that in SRES marker A1F1 the upper error bar (not the mean) shows that if we do nothing at all, business as usual, about climate change then by 2099 sea level could go up by +0.6 meters amsl (above mean sea level – present day). That’s about 2 feet.

    Hearty et al (2007) provide a synthesis of a dozen last-interglacial (the Eemian) sea level studies. Scroll down and look at Figure 2 very carefully. Many of these studies show that the end-Eemian second thermal excursion was the strongest netting anywhere from a +6.0 meter amsl rise to a +45 meter amsl rise, right at the very end of the most recent interglacial!

    That means, if we just consider the environmental instabilities documented at the very end of the last interglacial, then the AGW “worst case” (and the upper error-bar at that) of +0.6m comes in at just 10% of the lowest estimate of what happened anyway right at the very end of the last interglacial. That means the natural, normal, end-extreme interglacial climate “noise” envelope is at least an order of magnitude larger than our worst projected climate impact “signal”!

    And there is no “pattern” from which to recognize our anthropogenic “signal”. The Anthropogenic “signal” will be the first ever. How will that be recognizable from noise an order of magnitude larger that is quite chaotic, especially at the ends of the interglacials?

    Comparing apples to apples here does not help. If we use the IPCCs “worst case” upper error-bar sea level rise by 2099 of +0.6 meters and compare that to the worst case for the end-Eemian of +52 meters amsl then the noise envelope expands to almost 2 orders of magnitude.

    How, on earth, are we going to detect a +0.6 meter signal from a background sea level “noise” that is 1 to almost 2 orders of magnitude higher? If think you can detect our first climate “signal” ever from such a robust noise regime a future in signal processing is assured.

    At the very least 2 of the past 4 interglacials back in the record had stillstands and highstands higher than present. MIS-11, the Holsteinian interglacial (4th back in the record), topped out at +21.3 meters amsl at the end of its 3rd rapid thermal excursion occurring right at its very end. MIS-19, which happened at the MPT about ~800kyrs ago, also had 3 rapid thermal excursions right at its very end, the third one being the fastest and strongest. See Figure 2.

    In an attempt to keep the possible perturbations to a minimum we will assume CO2/GHGs to be as potent an insulator as is presently considered credible.

    The Holocene is 11,717 years old this year. A couple of centuries older than half the present precession cycle of 23kyrs (which would be 11,500). There is a fairly good possibility that we should either already be in the next ice age were it not for AGW (Ruddiman’s Early Anthropogenic Hypothesis), or on the cusp of it right about now. So if we decide to strip the anthropogenic GHG part from the possibly late Holocene atmosphere we might very well engender glacial inception!

    If thousands of years ago we had had the climate savvy we do now we could have already gotten rid of the anthropogenic climate security blanket and might already be well along into the next glacial.

    A deep summary of all this was provided by Tzedakis (2010)

    Having said all of that (and this comment is running longer than intended), it might not even matter. Perhaps the most poignant question a wise wise one (Homo sapiens sapiens) might ask oneself is how could we even tell if we were causing climate change, especially at the most recent end of an extreme interglacial?

    We could indeed strip the anthropogenic GHG component from what might very well be the late Holocene atmosphere. Sea level, the absolute measure of climate change, might go up something like 1 to 2 orders of magnitude higher than the anthropogenic “business as usual” worst case anyway.

    Why? Because it has, and it seems to do so rather dramatically, and regularly, as interglacials decay back to the cold glacial state.

    Several inconvenient truths should now be obvious. No one has yet put forth anything other than GHGs that could potentially stave-off glacial inception. If we remove GHGs to whatever concentrations are prescribed how will this address “The pronounced climate and environment instability during the interglacial/glacial transition could be consistent with the assumption that it is about a natural phenomenon, characteristic for transitional stages.”?

    The thing is we really do not know how long the Holocene should have lasted without us or with us. Even if we are right about CO2/GHGs, removing them from the late Holocene atmosphere could be enough to tip us into glacial inception:

    “Because the intensities of the 397 ka BP [end MIS-11, end-Holsteinian] and present insolation minima are very similar, we conclude that under natural boundary conditions the present insolation minimum holds the potential to terminate the Holocene interglacial. Our findings support the Ruddiman hypothesis [Ruddiman, W., 2003. The Anthropogenic Greenhouse Era began thousands of years ago. Climate Change 61, 261–293], which proposes that early anthropogenic greenhouse gas emission prevented the inception of a glacial that would otherwise already have started.”

    “Skeptics” and “Warmists” thus find themselves on the mutual chaotic climate ground where the efficacy of CO2 as a GHG had better be right.

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