Properly Framing Skepticism: A Reply to Knappenberger

Update: Please see the comments for further discussion.

A few weeks ago on the MasterResource blog, Paul Knappenberger noted that, in light of generally stagnant global average temperatures over the last decade (and falling temperatures over the last half dozen years), we might justifiably begin to doubt the reliability of the models on which much of the concern over global climate change is based. On the basis of this concern and a few allusions to other lines of evidence which seem to cast doubt on the case for alarm, Knappenberger concludes that:

While coming years may or may not continue the cooling trend of the past several, they will almost assuredly continue to add to the growing evidence that our coming climate will likely be far less detrimental than the popular projections of it to which we are often exposed.

In writing this response, I don't want to create the impression that I think that Knappenberger does a bad job in his post. I think he built a very reasonable case for concern over the reliability of climate models, and to a large extent I agree with him. About a year ago, I wrote a post on this blog discussing some of my reservations about climate modeling, noting that models raise uncertainty in at least five important ways: There may be problems resulting from "tuning" models; the IPCC uses averages from multiple models, potentially distracting us from serious and different flaws in each model; the models cannot effectively model small-scale phenomena which could be important in determining the future state of the climate system; they make use of proscribed variables; and they cannot effectively capture unprecedented, game-changing possibilities without opening themselves up to radical uncertainty. Knappenberger discusses a number of these issues in his post, and I think he does a good job.

But I do have one objection to his handling of the issue with which he concerned himself in his post: his conclusion was not at all supported by his argument. I believe that Knappenberger has mistaken the absence of evidence to be the evidence of absence. He coherently argued that climate models had made a vague prediction about what would happen in the future, and that since the prediction has not obtained as expected, we have reason to doubt that the climate models are reliable. However, he then appears to jump from the claim that climate models (which predict warming) are unreliable to the claim that warming is unlikely. But this jump cannot be sustained without further evidence.

To illustrate the problem, we might imagine that we are on our way to the mall with a particularly superstitious friend when she suddenly exclaims, "I bet we find a parking spot right away; we've gotten green lights the whole way so far, and that usually means I'm going to find a parking spot!" We might be skeptical of this claim, and regard her thesis as entirely unsupported. But what does that mean about the prediction that we'll find a parking spot? It simply doesn't tell us anything. We'd need to throw out our friend's claim entirely and appeal to entirely different lines of evidence to discuss the truth of the matter. In the same way, showing that climate models' predictions of future warming are unreliable does not suggest that there will not be warming. It simply suggests that we should place less emphasis on their predictions in forming our outlooks, or discard them completely.

The reason I belabor this point is that I think there's a broader point to be made here. There is a fundamental and important difference between an argument that says, "The state of scientific knowledge is not advanced enough that we can make a reliable prediction that distressing or catastrophic global climate change will occur in the relatively near future as a result of human activities," and an argument that says, "The state of scientific knowledge is advanced enough that we can make a reliable prediction that distressing or catastrophic global climate change will not occur in the relatively near future as a result of human activities." In his post, Knappenberger supports (effectively!) the first kind of argument. But in his conclusion, he advances the second kind, and without justification. I think it's critical that in thinking about climate change, we make sure to keep in mind this distinction and frame our skepticism in a way that we can defend.

On Alarmism and Denialism in Discussing Anthropogenic Climate Change

Every once in a while, someone brings to my attention a new article or video attacking the mainstream position on anthropogenic climate change, and I pretty much always end up responding with one of the following responses:

1) "This doesn't say anything that would be particularly troubling to the mainstream position. It simply highlights one area of uncertainty -- one which has already been acknowledged by the mainstream community. The balance of available evidence still supports the position that humans are likely having a significant impact on the climate system which will probably continue into the future, but considerable uncertainty does indeed remain. As scientists learn more, they could discover that they overestimated the significance of certain phenomena, or that they posited causal connections which either aren't there or are canceled out by other factors. But they could also find out that they underestimated those things, or that things are likely to be a lot worse than they thought. We simply don't know. The mainstream estimates provide "best guesses" about what might happen in the future, but there are no guarantees. Issues like this one show us just how much more we have to learn. However, it would be irresponsible to dismiss the mainstream position because it is grounded on science that is wrought with some uncertainty. As I said above, the balance of evidence points to some reason for concern, and that needs to be taken very seriously."

I think the paradigm cases which warrant this kind of response are the objections to proscription and tuning in models, questions about model resolution and intracellular processes, and uncertainty surrounding the impacts of aerosols, oceanic heat-transfer processes, changes in cloud dynamics, and solar phenomena (including the issue of cosmic rays). I like giving that kind of response a lot because I think it puts into perspective both the fact that we have a lot left to learn before we can be comfortable with our understanding of the climate system, and the fact that we can't just expect the scientific community to hold off on making predictions until we have perfect knowledge of what's going on.

The other kind of response I sometimes give goes something like this:

2) "Why would you listen to this person? He/She is not a climate scientist, clearly has not read the part of the IPCC report (or any other significant mainstream publication) that addresses the issue he/she is discussing, and seems to think that issues in climate science can be discussed through one-liners. If you don't want to actually learn about the issue at hand, then don't go around spouting your ignorant opinion, or tossing links around leading to other people spouting their ignorant opinions. It's infuriating that people even pay attention to this nonsense."

Unfortunately, I seem to give out more (2)'s than (1)'s by a wide margin. What needs to be recognized by those who receive these answers is this: The points discussed here do not apply with any more effectiveness to climate change alarmists or climate change denialists. Members of both parties are very often guilty of not knowing the first thing about the subjects that they're talking about (especially the individuals who come to deserve the (2) answer). People need to acknowledge that while the mainstream scientific position is not necessarily perfect, it is at least not flawed for simple, obvious reasons, or because there's some perfectly legitimate and groundbreaking scholarship out there that simply was never heard of by anyone.

There are certainly some large uncertainties, and a lot still needs to be done in order to get a proper handle on what we can expect for the future. But rather than try to frantically poke holes in the mainstream position, people should be spending their energy learning more about the basic concepts on which that position is built. Otherwise, I'm going to keep having to hand out more of those (2)'s, and I don't want to do that.

A Typical Response to Some Typical Climate Change Skepticism

I was recently informed that the fine folks over at Bureaucrash have started a social networking site, and so I set up an account. And almost immediately, I discovered a fun little climate scientist bash session. I figured I'd weigh in, and quickly found that my post had reached rather epic proportions. Given that I get questions about climate change all the time, I figured I'd post my response here for easy reference.

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Kevin, it's critical to realize that in the broadest planetary or biological terms, there's nothing wrong with global warming. You're right to point out that the Earth has been much warmer than it is today, and life did just fine. In fact, it flourished. So the problem is not that a warmer Earth would destroy life. Rather, the problem is that human civilization has been built up in a relatively narrow range of normal climatic conditions, and permanent shifts in those normal conditions would force people to undergo extremely costly adaptation. As John Broome writes in his book, Counting the Cost of Global Warming, "Unless there is a great ecological catastrophe, however, most of the harms that one can foresee from global warming could be classified as adjustment costs. I can see no reason why, in equilibrium, a warmer world should not be able to sustain just as good human life as a cooler one. The problem is that, over thousands of years, human beings and nature have become adjusted to a cooler world" (15).

Some indviduals' property would likely be destroyed by changing global conditions, and many would be put at increased risk of damage from extreme climate events. Some groups of people would find that the ecological conditions on which their livelihoods were dependent had changed, and this would create many problems, particular for many of those who are already among the worst off. So while a warmer Earth could likely eventually support lifestyles of equal or greater quality than it currently does, the difficulty of adapting the entirety of humanity to new conditions should give us pause. And that's not even to mention the impacts on the Earth's other species which, whether or not we attribute them intrinsic value of their own, certainly help to enrich our lives. As I've discussed in a paper that I'd be glad to send to you if you'd like, some of these effects could reasonably be thought of as infringements on rights, while others simply as objectionable consequences. But insofar as rights are involved, it seems like the proper libertarian response if we knew that climate change were occurring would mean something more than simply allowing people to adapt; we certainly wouldn't advocate that sort of solution for the victims of theft.

As for the scientific case for climate change, I think Stephen Gardiner put it well in his essay "Ethics and Global Climate Change" when he pointed out that "The skeptics are right…when they assert that the observational temperature record is a weak data set and that the long-term history of the climate is such that even if the data were more robust, we would be rash to conclude that humans are causing it solely on this basis. Still, it would be a mistake to infer too much from the truth of these claims. For it would be equally rash to dismiss the possibility of warming on these grounds. For, even though it might be true that the empirical evidence is consistent with there being no anthropogenic warming, it is also true that it provides just the kind of record we would expect if there were a real global warming problem" (567).

You point to several lines of evidence which you take to contradict the mainstream hypothesis, and I think that those should be addressed. You first point to the time lag between historical shifts in temperature trends and increases in levels of CO2. It should be made clear that no one is alleging that amphibians were driving their SUV's around, warming the Earth in time for the age of the dinosaurs. Rather, as temperatures rise, we would expect CO2 levels to rise, as they [higher temperatures] stimulate biological activity among heterotrophic organisms and cause aqueous CO2 to bubble off from the oceans. But these increased CO2 levels would be expected to create a feedback effect; the equilibrium temperature should be higher in those periods than it would be expected to be without any effect from CO2 warming, and indeed paleoclimatologists cannot explain climatic conditions in those time periods without citing the effects of an amplifying CO2 feedback. The problem is that today, we are adding a temperature amplifying agent to the atmosphere; this should be expected to produce some warming (ceteris paribus), no matter how skeptical you are about the anthropogenic climate change hypothesis (there may be counteracting consequences of increased CO2 levels, of course, in our current time period; I don't mean to marginalize that possibility, but those mechanisms have not appeared to be present in the past, as far as we know). It's simply a scientific fact that CO2 absorbs long-wave radiation.

You then point to the lack of temperature increase in this century, in the face of continually rising levels of CO2, as counter-evidence. I'd point out that your counter-hypothesis is based on the idea that practically all of the temperature variation we saw in the 20th century can be attributed to natural variability, and yet you are apparently pointing to a point in time where temperatures are not rising with the implication that there could not possibly be any natural trends which are currently counteracting the warming influence of atmospheric CO2. This seems like a structural problem for your position, but you could still be correct if we had no way to even begin to understand why global temperatures might not be increasing right now. Perhaps unfortunately (since it would be very nice if you were right), I believe that many scientists are claiming that the sun (which is certainly important in driving climatic conditions) has been in a relatively quiet period, and that this should be expected to cool the Earth. Given that the Earth has not cooled, this is unfortunately somewhat legitimate as evidence in favor of the anthropogenic climate change hypothesis: if the Earth gets warmer during times when natural trends alone would be expected to warm it, but does not get cooler when those trends would be expected to cool it, then it suggests that natural trends might not be able to provide the whole story, and the CO2 forcing may be the missing component.

Finally, you point to the fact that water vapor is the most significant greenhouse gas in the atmosphere, and on this point you are absolutely correct. Without the greenhouse effect, scientists believe that the Earth would be almost 60 degrees Fahrenheit colder than it is today. We have water vapor to thank for most of that warming, without which life as we know it would be completely impossible. Current estimates of future climatic conditions tell us to expect a change about an order of magnitude less significant than the total warming produced by the natural greenhouse effect. And that makes sense, given that the overwhelming majority of the greenhouse effect is the result of atmospheric water vapor. I'd also point out that predictions about future temperatures are not solely based on the greenhouse effect from increased levels of CO2, but also on a number of feedback mechanisms, including decreasing planetary albedo and, incidentally, increasing water vapor.

I'm sure you have a large number of further objections to the mainstream hypothesis, likely including but not limited to claims about cosmic rays, the incapacity of models to properly account for cloud activity or other intracellular activity, the proscription of variables in GCMs, the uneven vertical distribution of warming between the lower and upper atmosphere, the inherently cyclical nature of the climate system, and the apparently strong relationship between global temperatures and solar activity in the mid-20th century. I'd only suggest that perhaps you take some time to study the IPCC report and a basic textbook on the scientific basis for the anthropogenic climate change hypothesis, rather than regurgitating talking points from climate skeptics, and also recognize that uncertainty about the scientific basis for concern about climate change does not free libertarians of the responsibility of explaining what they would say if they knew that climate change were occurring.

What Does It Mean to Advocate a Market Solution to Climate Change?

The purpose of this post will be to tie together some ideas I've been toying around with in other posts, in order to start working towards a coherent introduction to my thesis on the libertarian approach to thinking about climate change. Here goes nothing.

Moving Past the Science

As a group, libertarians have not dealt well with the prospect of anthropogenic climate change. As most of the world scrambles to find "solutions" to what they anticipate will be a serious problem for human civilization, the typical libertarian approach to the issue has been to deny that climate change is real, or to deny that humans have caused it. There are two problems with this position. First, the most vehement critics of what has become the "mainstream" view are not particularly well qualified for their missions, and often demonstrate a misunderstanding of their opponents' views which seem to indicate that they don't actually know what they're arguing against. Further, where there are well-qualified and well-informed "skeptics," their positions tend to be less vitriolic and more nuanced, being based more on uncertainty and imperfect knowledge, to the point where their views end up falling relatively close to those which are accepted by the mainstream scientific community. As far as I can tell, a relatively strong case can be made in favor of questioning our ability to know the precise truth about climate change, and our ability to predict future states of the climate; the same cannot be said about the position that climate change is not happening, or that humans are not causing it, or that it will not continue into the future in any significant way.

This leads to the second problem with the libertarian habit of questioning the scientific basis for concern about climate change: it does not address the question of what position libertarians would endorse if climate change were happening. There is no reason to believe that anthropogenic climate change, or some substantively similar phenomenon, could not happen. Accordingly, it seems extremely reasonable to ask what libertarians would say about such a phenomenon, if we knew that it was occurring right now. In this article, I will sketch the kind of answer we should be looking for.

Market Failures and Government Inefficacy

Where climate change has been discussed, by libertarians and others, it has generally been labeled as a market failure. Economic theory tells us that market failures occur whenever inefficient social outcomes result from individuals acting on their own desires. Looking at climate change from this paradigm, we would notice that for most individuals, the benefits of, say, driving a car instead of taking the bus more than outweigh any costs they would ever incur from their incremental contribution to climate change. Accordingly, it will be in everyone's interest to drive their car. But the predictable result of everyone making the sort of choices that result in driving everywhere, instead of using public transportation, is that we end up with climate change. As Garrett Hardin famously wrote "...we are locked into a system of "fouling our own nest," so long as we behave only as independent, rational, free enterprisers."

Simply recognizing this problem will not solve it. Mitigating climate change will involve sacrifices, and individuals will undoubtedly resist making these sacrifices if they do not have the assurance that others will follow suit. Unfortunately, getting individuals to voluntarily cut down on their contributions to climate change would be fraught with difficulties, ranging from the large costs of negotiating the agreement to the pervasive incentive to "cheat". These hurdles seem to rule out the kind of decentralized solution that the free-market is capable of providing. The most obvious and widely discussed solution is the one Hardin suggests: legislation. If we know that we will "foul our own nest" if left to our own devices, then it seems reasonable to impose rules on ourselves, and to punish those who violate those rules, in order to ensure that we don't bring about our own destruction.

But many libertarians bristle at the suggestion that central planning can solve the problems presented by market failures. It seems unreasonable, they argue, to suggest that we can fix an imperfect market by simply turning the matter over to the government. After all, governments have problems of their own. As Gene Callahan points out, "Government interventions and "five year plans," even when they are sincere attempts to protect the environment rather than disguised schemes to benefit some powerful lobby, lack the profit incentive and are protected from the competitive pressures that drive private actors to seek an optimal cost-benefit tradeoff."

Accordingly, a number of libertarians have apparently taken the stance that we cannot hope for an "optimal" level of climate stability, so our best option is to simply face the realities of our suboptimal state of affairs. And because, they continue, the free market is the most efficient system we know of for allocating resources to best suit the needs of society, the best way to face climate change would be to allow individuals the freedom to adapt in their own way. As George Reisman writes, "Even if global warming is a fact, the free citizens of an industrial civilization will have no great difficulty in coping with it - that is, of course, if their ability to use energy and to produce is not crippled by the environmental movement and by government controls otherwise inspired."

Climate Change: A Matter of Justice

This view of the issue leaves out an important consideration which is central to the libertarian paradigm: According to most accounts, climate change will have victims. This fact brings us out of the realm of mere economic efficiency and forces us to confront the issue from an ethical standpoint. Imagine if we were trying to determine the proper social response to a particular theft. It might be true that of all social systems, a victim of theft would be best equipped for dealing with her loss in an unfettered free-market. She would not need to consult a central planning board in order to replace the things that were taken, and her higher purchasing power – brought about by her participation in a thriving market economy – would enable her to afford the replacement with comparative ease.

But surely libertarians would not be satisfied with this “solution.” In our story, the thief violated the rights of his victim by stealing from her, and therefore he should be held accountable for fixing the damage he caused. It is crucial to acknowledge that holding the thief responsible does not represent a departure from the normal course of the free-market; the very functioning of the free-market is predicated on the recognition of rights. This reveals an important feature of the libertarian position that the proper response to climate change is to simply allow individuals the freedom to adapt to it: It assumes that climate change does not represent an injustice. If climate change were an injustice, then the proper response would not simply be to allow people to adapt: libertarians would need to advocate the enforcement of justice.

Accordingly, it seems like the proper libertarian stance on climate change needs to be stated in terms of justice. The scientific disputes and efficiency-based arguments which have thus far characterized the libertarian position are wholly unbecoming of a political philosophy built on the foundation of respect for individuals’ rights. The libertarian community needs to ask what kinds of rights, if any, are infringed by climate change, and what should be done about those infringements. Anything else would simply be unlibertarian.

On the Sun as the Cause of Climate Change

So I've reached the point where I've heard enough people tell me that "The Sun is responsible for climate change, and the mainstream view is just another example of alarmist propaganda by the fascist environmental movement!" where I feel like it's necessary to say something about it. Doesn't it seem odd to anyone that the overwhelming majority of people who've studied the climate for their entire lives disagree with a view that's been around for well over a decade, but a significant chunk of the general public still believes it to be true? And doesn't it seem even odder that between the two groups, it's usually only the scientists who've actually read the work on which the solar hypothesis is grounded?

Accordingly, I hereby declare that anyone who wants to say that the Sun is responsible for climate change, and people are not, should have to actually at least some research. To be clear, I have no problem with the view that "The relationship between solar variability and the climate system is poorly understood, and therefore represents an area of considerable uncertainty in climate research." But that's what the alleged "eco-fascists" think. If you're going to take the view that the mainstream is wrong and stupid, I think you should have to at least figure out what the mainstream thinks. Don't worry; I'll help!

The first place to start is the IPCC's very short answer to the question, "Can the Warming of the 20th Century be Explained by Natural Variability?" in Chapter 9 of its report, on pages 702-703. Basically, the IPCC concludes that the 20th century's climate pattern doesn't seem to bear the characteristics that we would expect if it were caused by natural variability, and does bear the characteristics that we would expect from a greenhouse gas driver (in my opinion, the most convincing piece of evidence is the cooling of the stratosphere, but perhaps unidentified and therefore unquantified solar influences on atmospheric chemistry and circulation could be responsible for that).

Because the simple answer won't satisfy anyone, the next step is the IPCC's discussion of "Solar Variability" in Chapter 2 of its report, on pages 188-193, part of its examination of various radiative forcings on the climate system. In it, the IPCC basically says that the direct effect of changes in solar irradiance can't explain the changes we've observed, but we don't really understand all of the indirect effects of the Sun on the climate system. Still, it doesn't seem like the Sun is responsible, because we haven't regularly observed the patterns we would expect to see if it were responsible. So while it's possible that we just don't understand what's really going on, and the Sun really does play a critical role in shaping the Earth's climate, there isn't really any evidence that would be decisive in this regard.

While I think those resources provide a pretty decent summary of the state of the science, I think some people might think that they come off as not really taking the question of solar forcings seriously. Accordingly, a more comprehensive examination of the issue (which is heavily relied on in the IPCC's discussion) can be found in a Hadley Center report on "The Influence of Solar Changes on the Earth's Climate." I haven't read the report myself, but I would assume that it does a good enough job that anyone who really wants to know what mainstream scientists think about the Sun's influence on the climate would be able to find what they're looking for.

I suspect, though, that when they point to the Sun as the cause of climate change, most people are relying on what they've heard about the work of certain scientists, most popular among whom I perceive to be Henrik Svensmark of the Danish National Space Center. Accordingly, it's probably worthwhile to bring up Peter Laut's controversial paper, "Solar Activity and the Terrestrial Climate: An Analysis of Some Purported Correlations," in which Svensmark and others are basically called bad scientists (though with a little more tact) because they manipulated data and used questionable scientific practices in order to justify their conclusions. Laut and Paul Damon published another shorter article titled, "Pattern of Strange Errors Plagues Solar Activity and Terrestrial Climate Data," which basically summarized the pair's earlier work and besought the general public to please stop drinking Svensmark & Co.'s Kool-Aid.

Needless to say, Svensmark & Co. weren't too pleased about this, and responded accordingly. Regarding the first paper, Svensmark released this rebuttal, and after the second one was published, Svensmark and Eigel Friis-Christensen (an important member of Svensmark & Co.) had this to say. The highlight, I think, has to be the conclusion of the latter, which says, "In summary, Laut's methodology consists of first writing false accusations, then totally neglecting the refutations, and finally referencing his very own claims as corroboration when publishing new accusations. This is in our view an interesting, but also the very only, conclusion that can be drawn from the article." So I guess one should take Laut's criticisms with a grain of salt, given the vigor with which they were disputed by their targets. I'm honestly not in a position to evaluate them, given my lack of statistical training. But if you're going to subscribe to Svensmark's views, I do think it's worthwhile to take his detractors into account.

At the end of the day, I don't think it's fair to conclude that the sun is responsible for climate change, and humans are completely innocent. As I wrote in this article, we have every reason to believe that greenhouse gases and other anthropogenic influences have played some role in shaping the state of the climate, and will continue to do so in the future. By the same token, I do think that we would be wrong to completely ignore the possibility that the sun has played more of a role than it's currently given credit for. But to say that the mainstream is espousing propaganda to fuel some sinister agenda because certain physical mechanisms aren't well understood seems flat wrong. That's especially true in light of the lack of any really convincing evidence in favor of the solar hypothesis, and the amount of effort spent to understand the nature of the Sun's influence by the mainstream climate science community.

Bob Carter on Climate Change (Part IV)

Carter starts part 4 with a discussion of the urban heat island effect, which he thinks has significantly affected our ability to talk about global temperatures. Now, it's true that the heat island effect needs to be taken into account, and happily, the 2007 IPCC report has taken the first steps towards doing just that. Current research into the effect will likely not satisfy those who believe that it has significantly skewed the data, but several scientists have attempted to quantify the heat island effect, and the consensus is currently that the effect is not very significant.

It's true that some weather monitoring stations have been placed where temperatures would be expected to be higher than the surrounding areas. Carter refers to Anthony Watts' work, and Watts' old blog is actually a fantastic resource for seeing exactly what this means. If you haven't checked it out, you absolutely must. But this phenomenon has been the subject of several studies, and apparently other weather monitoring stations have also been placed in statistically cooler areas, like parks, which would tend to skew the data towards lower temperatures, and while the result isn't completely neutral, it can't account for the whole warming trend over the past century.

I'm glad to see that Steve McIntyre got a mention in this presentation. Poor Ross McKitrick (McIntyre's partner in the discussion of the hockey stick controversy) must feel terribly left out! But unfortunately, Carter talks about McIntyre in order to dredge up a piece of information that I was really hoping he wouldn't dredge up: the whole 1934 controversy. This issue has been widely discussed, and if you take it seriously, the reasonable conclusion is that it doesn't really matter, except to show that climate scientists are human, and mistakes are to be expected. Good thing the IPCC doesn't base its statements on any single study, but rather on its appraisal of the state of scientific research, or else this might be relevant!

But returning to the heat island effect, Carter points to some problems in a paper written by one of the co-authors in a major study of the heat island effect as evidence that the IPCC couldn't have properly accounted for it. But take a moment to think about that. The 2001 IPCC report (not the latest one) does rely heavily on the work of Jones et al. And part of that "et al" was apparently this Wang fellow. Wang wrote a completely separate paper which discussed the urban heat island effect in China (incidentally, Wang's paper is not directly cited in the section regarding land-surface air temperatures in the IPCC report). And some other guy wrote something which accused Wang of fabricating something in his paper.

Now, we have no way of knowing whether Wang could have defended himself against this accusation, or who this guy is who's leveling it. And we also have no idea whether the accusation has anything whatsoever to do with the paper Wang wrote with Jones. And really, it's Jones' paper that we care about, even though it's only one of a number of papers that the IPCC considered when writing its evaluation of the heat island effect. So I'm forced to wonder, what the hell does this prove about anything? Is this honestly the best case against the IPCC's assessment of the heat island effect? Before I watched this video, I was of the opinion that the heat island effect was a new field of research, and we shouldn't jump to any conclusions about it, even if the IPCC thinks that the evidence points towards it having a negligible effect. But what does it say that Carter had to resort to this kind of argument? Perhaps the IPCC's case is even stronger than I thought!

With that, Carter's assault on the science of global warming is complete. It should be clear that his case doesn't really work, even though some of his arguments do point to areas of considerable uncertainty in climate change science. I'm also forced to wonder how he takes his presentation seriously; if I can pick apart his arguments, then how can he possibly think that they're right? Isn't he supposed to be the climate scientist? I honestly don't know what to say. Perhaps I've just been brainwashed by the alarmist Kool-aid I've been served by the scare-mongering climate scientists!

But even though he's just completely dismissed the basis for believing that global warming is a problem, he moves into a discussion of the economics of climate change. So apparently, despite the fact that we have no reason to believe that anthropogenic climate change is real, and all our predictions are nonsense, we can still coherently talk about the costs and benefits of the climate change that we have no reason to believe will happen, because apparently the estimates of the costs and benefits aren't completely worthless if the premises they used in their calculations are completely false. But because I think Carter's flat wrong about the science, I'm interested to hear what he has to say about the economics.

William Nordhaus is indeed one of the central figures in the climate change debate, having come up with the conclusion (famously relied on by Bjorn Lomborg and others) that climate change will not be anywhere near as damaging as might otherwise have been expected. As I mentioned in my last post, a lot of people who say this come to their conclusion by discounting future damage by some "social discount rate," and Nordhaus is actually who I had in mind when I said that. Because Carter mentions Nicolas Stern, it's worth pointing out that Stern doesn't discount, and a large part of the difference between their conclusions is the result of that fact. But nevertheless, the article I linked in my first post discusses what I think about the sort of argument Carter gives here.

In closing, I want to say that while this has been a worthwhile exercise for me, it's important to note how much work it just took for me to do this. The fact that climate change skeptics are generally ignored is, I contend, merely a testament to this. It takes time and energy to deal with nonsense, and frankly, most people have better things to do. In fact...why did I do this on my Thursday night? Bummer! But anyway, I hope that somehow, this was helpful to someone; I'd love to hear what people think!

Bob Carter on Climate Change (Part III)

[Read Part I and Part II first!]

Carter begins part 3 of his lecture with his second "torpedo": Richard Lindzen's Solar Iris hypothesis. In what has to be the most infuriating part of the lecture so far, he claims that Lindzen's hypothesis has been verified by the fact that cirrus clouds dissipate after a rainfall event, entailing that rain allows more heat to escape into the atmosphere. But as far as I can tell, the argument about the Solar Iris effect isn't about that. It's about whether or not higher ocean temperatures would encourage more efficient precipitation and changes in cloud characteristics. The whole point of Lindzen's hypothesis is to suggest that global warming will be mitigated by a negative feedback caused by changes in rain patterns and cloud cover. That is, as the oceans get warmer, they'll evaporate more, which will cause more efficient precipitation and changes in cloud characteristics which will allow more heat to escape into space, thereby reducing warming. Demonstrating that precipitation affects clouds doesn't prove anything of any relevance. Carter would need to show that increases in ocean temperatures have the sort of effect Lindzen discusses, and he doesn't do that. So "torpedo" two misses its target as well.

Torpedo 3 is much more to the point. Carter rightly points out that concern about climate change is largely drawn from anticipated positive feedbacks thought to occur in the event of warming. On its own, an increased atmospheric concentration of CO2 wouldn't produce the kinds of problematic changes in global temperature that are generating concern among scientists. To be clear, there would be other consequences (like acidification of rain and the oceans, as well as increased capacity for plant growth in water limited areas and better growing characteristics in other places), but the concern about temperature is largely based on predictions of positive feedbacks. Carter gives the example of water vapor, but other positive feedbacks have been described. For example, as temperatures rise, glaciers and ice sheets would be projected to retreat. Because ice is white, while soil, rock and ocean are dark, retreating ice increases the absorption of light by the Earth's surface, resulting in warming.

But it's certainly possible that Carter is right, and on the balance the Earth system is dominated by negative feedbacks. If that were the case, then perhaps concern over climate change is overblown. But the current stance taken by the IPCC is that we have no reason to believe that Carter is right about this, and it's actually quite likely that we've underestimated the positive feedbacks, and climate sensitivity is actually greater than we currently give it credit for being. So for people who say that the science is settled and we can all go home, this point should serve as a wakeup call. But that's not to say that the mainstream view is not aware of it. In fact, the study of feedbacks is one of the most important parts of climate research today, and we're learning more about how they work all the time. So while Carter is right to say that this is an area of uncertainty, it's absolutely unfair of him to say that it in any way disproves the mainstream view. In fact, it's central to the mainstream view, and explains the caution with which the IPCC makes its predictions.

Carter, however, cites a prediction by Stephen E. Schwartz that pegs climate sensitivity at 1 degree for a doubling of CO2. I'm not familiar with the exact paper that he refers to, but I've read some stuff by Schwartz, and I know that he's both controversial and intelligent. So I won't discard Schwartz' opinion as nonsense, because I respect him tremendously, but I also would caution against taking his views as proof of anything.

And I would strongly disagree with Carter's claim that this "torpedo" is devastating to the mainstream assessment. The mainstream view is the result of a comprehensive examination of the available opinions in the field. Taking the conclusions offered by one paper as proof that the mainstream view is wrong is just irresponsible. This is especially clear when Schwartz' prediction actually falls within the confidence interval of the IPCC prediction! So it's not even like the IPCC is saying that Schwartz' prediction is wrong! It's simply saying that most scientists disagree, and for good reasons, but it's certainly possible that Schwartz is right. The strongest thing Schwartz could say in objection is that his confidence interval extends significantly below that of the IPCC, and so some low levels of sensitivity he thinks are reasonably likely are held to be highly unlikely by the IPCC. But if I had to, I could undoubtedly find you a whole collection of reputable scientists predicting at the high end of the interval, upset about the conservative predictions being made by the mainstream community. So to use Schwartz' paper as a "torpedo" is just patently absurd, and I'd suspect that Schwartz might agree (though he'd probably attack the mainstream opinion for other reasons, some of which I likely touched on in this post).

Carter then goes on to lambaste some climate modelers for not being able to properly model the climate. He doesn't actually go into the reasons that modeling might fail, but in the aforementioned post, I briefly sketched some of those kinds of problems, and I happen to think that attacking climate models is a potentially fruitful avenue of attack on mainstream concern. I do think, though, that Carter was out of line in the degree to which he ridiculed these modelers. It's not fair to make them the whipping boys for the problems with modeling. And it's also not fair to suggest that models in general can't be relied on because this one attempt at a climate model didn't produce very good results. Maybe the paper wasn't accepted because of its model; maybe it was worth publishing for some other reason. I've seen model reconstructions, and while they aren't all the best, they're certainly not as awful as he makes them out to be.

In the middle of his tirade, Carter slips in the suggestion that the sun is actually to blame for climate change, which is much more controversial than it looks on the graph he uses. Actually, the solar influence on the climate system has been widely studied, and the IPCC has made an attempt to quantify it. Of course, it's possible that the IPCC doesn't have a good handle on all of the effects of the sun on the Earth system (as has been suggested by people like Willie Soon, Sally Baliunas, Henrik Svensmark, and many others). But while I'm not sure I'm convinced that the solar hypothesis has been disproved, I do think that a lot of work needs to be done if it's going to withstand some of the more convincing criticism it's received.

We'll see if Carter leans on this point in the next part, but hopefully he doesn't, since it's not really the most fruitful line of attack.

[Go on to Part IV]

Bob Carter on Climate Change (Part II)

[Read Part I first!]

It seems that the link Dr. Hunt sent me did not contain parts 2-4 of the lecture. But never fear; I found part 2 on YouTube, so you can watch it there.

In this part, Carter starts off by trying to interpret the temperature trend in the late twentieth century. This makes me a little uneasy because he actually comes out and says that his explanation of the data set as an instance of a step shift is somehow "a much more reasonable interpretation of the data." To illustrate why, it should be noted that an equally plausible claim would be that the trend was flat from 1975 to 1990, and then began to scale upwards in a linear fashion until the present time. But more important is the fact that he's suddenly moved from a time scale of hundreds of thousands of years to a scale of about a quarter century, and is now suddenly interpreting trends, even though he just said that climate trends can't fairly be discussed on such short time scales. To be clear, it's pushing it to say that we can isolate a trend in a century of climate data; it's completely ridiculous to attempt to do so definitively for a time span of three decades, and then say that any other interpretation is flat wrong.

As I feared, Carter's next move is to suggest that the climate has indeed entered a period of "stasis" over the past several years, during a period in which atmospheric levels of CO2 have risen, and therefore the anthropogenic climate change hypothesis has been falsified. Keep in mind that he's just gotten through suggesting that the climate is characterized by extreme levels of natural variability, and that he seems to be implying that it is this variability, and not anthropogenic CO2 emissions, that are responsible for the temperature variations that we've seen over the past century. But if natural variability could be responsible for the entire temperature variation over the twentieth century, why couldn't it be responsible for the recent discrepancies between actual warming and the influence of CO2? That is, why couldn't CO2 be causing the climate to warm, but natural variability be causing the climate to cool, resulting in no trend? I can't think of any reason.

That's not to say that the past several years don't need to be explained. Surely they do. But they shouldn't be taken as proof that anthropogenic climate change isn't happening. They offer no stronger support of skepticism than a decade of warming would offer in support of an anthropogenic climate change hypothesis. And surely if the past decade showed a warming trend, we wouldn't hear that the skeptics had given up. So it just seems like an odd point to try to make. Of course, if the models on which concern about climate change is based predicted warming over the past decade, and there hasn't been any, then it seems like we would have a bigger problem. But I haven't heard anything like that, and Carter isn't saying it, so I'd suspect that it hasn't happened. And if it hasn't happened, then it's likely that it wasn't really contrary to mainstream expectations at all.

That, of course, shouldn't be taken as proof against Carter. But it certainly raises the question why, in a time period in which the IPCC has been working on its latest report which has just recently been released, was no one making a huge deal about this issue? Why is some geologist from Australia the first one to bring it up? It seems much more likely that it's because it's not an issue than that it simply never occurred to anyone.

Carter's next point is, essentially, that some Australian scientist guy doesn't believe that climate change is occurring, that a committee of some sort potentially overstepped its boundaries by making statements it wasn't qualified to make, and that most people who talk about climate change don't know what they're talking about. I honestly see no reason to object to any of these claims, but I'll point out that they have absolutely nothing to do with anything, and certainly aren't a "torpedo" against the mainstream view.

He moves on to say that governments around the world have agreed that "the Alarmist case does not stack up." And this is true, except that the "Alarmists" those governments are talking about are the ones predicting certain doom and catastrophe, while Carter seems to be implying that anyone concerned about climate change is an alarmist. This isn't fair, but it's a rather minor point anyway.

Carter ends the section by comparing the mainstream opinion to a religion. Given what he's said so far, I think it's fair to say that he either hasn't read the IPCC's reports, or is intentionally misrepresenting them. The fact of the matter is that the science is available for anyone to see. The reason that people like Carter get shouted down is that they misrepresent the science and convince people of things that aren't supportable, even with the data that Carter uses. But more importantly, people like Carter get shouted down because the people who could explain why they're wrong are too busy to deal with people like Carter. Just look at how much time I've just spent critiquing 17 or so minutes of Carter's speech. It's simply not worth it for a reputable climate scientist to go through this every time a Bob Carter comes around spouting a bunch of nonsense.

But I'll forge on to the next section; hopefully things get better and not worse...

[Go on to Part III]

Bob Carter on Climate Change (Part I)

One of my professors, Dr. Lester Hunt, turned me on to a very interesting lecture given by Australian geologist Bob Carter on the subject of climate change. I figured that it would be worth critiquing the lecture as I listened to it, because it seems like one of the more respectable attacks on the mainstream views regarding climate change, and it might be helpful to have gone through an exercise like this to respond to skeptics in the future. Since Carter's talk is broken up into four parts, I'll break my critique into four parts as well (this post responding to the first part). I'll also keep my comments to points of disagreement or tension between my own views and Carter's. He has a lot to say, and I'll likely agree with most of it.

One of the first points Carter brings up is one which was made most famous by Bjorn Lomborg, which is that it would require significant energy and resources to do something about climate change, and more benefit would come from doing things about more pressing current problems like global poverty. Though Lomborg has written multiple books on the subject, his views are more or less captured in this speech he gave to Congress last year. I have a lot of sympathy for this viewpoint, though most people who hold it come to their conclusions by discounting future costs by something of a “social discount rate.” I’ve written about discounting damage caused by climate change in a paper I can make available by request. But it’s possible that even without discounting, the damage associated with climate change is significantly outweighed by the damage caused by things like poverty, hunger and AIDS. I’ve discussed this possibility here, concluding that while I see where Lomborg is coming from, I believe that if we're responsible for causing climate change, then the damage it causes is morally different than damage caused by things we're not responsible for bringing about, like hunger and AIDS.

Carter moves on to a slide discussing the long term temperature trends displayed by "Greenland ice cores." This is an intriguing move, because one of two things could be happening, and because I'm writing this critique as I'm watching, I'm not sure which it is. The first is that he's being honest and showing that different proxies in different regions show very different things, and that it's extremely difficult to separate global trends from regional anomalies and noise. This is especially important because the time period we're analyzing in discussing climate change is extremely short. And when talking about climate change in the context of historical climate conditions, we're forced to rely on these proxies because before about 100 years ago, we weren't able to acquire reliable human-instrument-measured temperature data.

This sort of view was put best, I think, by Stephen Gardiner in his 2004 essay, "Ethics and Global Climate Change," in Ethics, Vol. 114 , No. 3, pages 555-600 (and yes, I think I will cite this quote in every post on climate change, thank you very much). On page 567, he wrote, "The skeptics are right...when they assert that the observational temperature record is a weak data set and that the long-term history of the climate is such that even if the data were more robust, we would be rash to conclude that humans are causing it solely on this basis. Still, it would be a mistake to infer too much from the truth of these claims. For it would be equally rash to dismiss the possibility of warming on these grounds. For, even though it might be true that the empirical evidence is consistent with there being no anthropogenic warming, it is also true that it provides just the kind of record we would expect if there were a real global warming problem."

But the dishonest thing he could be doing, which is so obviously dishonest that it would be fair to question his intentions if he were doing it, is suggesting that the Greenland ice cores are representative of the historical global temperature record. To do so would be just as dishonest as focusing on the fact that in North America, 1998 was no warmer than 1934, even though worldwide, 1934 was a significantly cooler year than 1998 (which is true, by the way). But it would be especially dishonest of him to infer from this something like "Global warming is likely due to natural variability" or "Over the last 8 years, global warming has halted, as we can see from these Greenland ice cores." But let's see what he actually does say.

What he does, incidentally, is move onto the idea that we're currently in an unusually warm period of time, and that we can expect that in the future, the world will become much colder than it is today. This time I'm not sure what point he's trying to make if he's not being intellectually dishonest. It's true that some time over the next several millenia (or maybe less), it's probably fair to predict that the Earth will enter a prolonged cooler period, where humans will likely be driven towards the equator in order to avoid the encroaching ice caps characteristic of the Pleistocene era (the period between 1.8 million years ago and about 11,550 years ago), as there is indeed no reason to believe that the Holocene warming (the period we live in) represents an end to the Pleistocene.

But it's also true that all of human civilization arose during the Holocene warm period, so it's irrelevant to point out that the climate is "typically" colder than it is today. This is especially significant because I haven't heard any predictions that the next glaciation is to come any time soon. If we can predict dangerous warming over the next several centuries, then I'm not really sure how it's relevant to point out that in several thousand years, we'll likely experience another ice age. Impacts on humans need to be discussed over smaller time scales than the extremely large geological time scales that he's using.

The last point he makes in this section, regarding the polar bears, is an important one. Most scientists don't believe that polar bears will likely become extinct as the result of climate change, though their habitat will likely be reduced significantly. Polar bears have been around a very long time, and will likely figure out how to make do. That being said, this speaks more to sensationalism in the media than the scientific basis for concern about climate change, and so it's not clear why he brings it up at this point, unless it's just for comic relief. I wonder, though, if that's a penguin on that grill; polar bears and penguins live on opposite ends of the Earth.

So far, I can't object to any of the facts Carter has brought up, but I'm sort of uncomfortable about the way that he's presented them. He's been good about not actually saying anything that's false, or drawing any conclusions which he has no right to draw. But he has seemed to imply a lot of things which aren't right, and if I didn't know better, I would think he was trying to lead people astray. Anyway, on to the next section!

[Go on to part II]

Do You Believe In Global Warming?

Earlier this evening, I got the following message from Ellis Wyatt:

"I'm curious-- in your research, have you come to the conclusion that climate change, at least at the hands of mankind, is provable? There is quite a lot of evidence to the contrary, and the State has done a great job of funding a lot of smokescreen research."

I wanted to address this on the main blog, rather than simply replying to it in some tucked away place where it would quickly be forgotten. So here goes nothing:

I think Stephen Gardiner put it best in his essay, "Ethics and Global Climate Change," when he wrote, "The skeptics are right…when they assert that the observational temperature record is a weak data set and that the long-term history of the climate is such that even if the data were more robust, we would be rash to conclude that humans are causing it solely on this basis. Still, it would be a mistake to infer too much from the truth of these claims. For it would be equally rash to dismiss the possibility of warming on these grounds. For, even though it might be true that the empirical evidence is consistent with there being no anthropogenic warming, it is also true that it provides just the kind of record we would expect if there were a real global warming problem."

There is very considerable evidence that climate change is being caused by human influences. Specifically, we have seen the most warming in the lower atmosphere, and a slight cooling in the upper atmosphere, which is consistent with a greenhouse gas driver. We have detected a clear warming trend during a period in which we would expect natural processes to have caused a cooling. And climate modelers are unable to reproduce historic climatic conditions without taking into account the influence of the roles of the factors which are believed to be responsible for current warming. Further, when modelers do incorporate what they believe to be the influence of anthropogenic factors, they are able to reproduce observed temperature fluctuations with a reasonable degree of skill.

That being said, it's certainly possible that the evidence is coincidental, and that modelers simply don't understand how the climate system works (though I'd say this possibility is relatively remote). I'd say that the IPCC was likely being fair to the available evidence when it said that it was very likely that humans have been responsible for most of the warming we've been seeing. That being said, it seems to me that considerable questions remain about the IPCC's predictions about future warming.

One danger is the possibility of model "tuning," which is where a model is designed in a way that makes it fit the data set, but doesn't accurately model the factors which caused the data set to have the characteristics that it has. It could be that rather than actually modeling the climate system, climate models are simply modeling the data sets, which would make them useless for predictions. Scientists are aware of this problem, and try to prevent if from having a significant influence, but given the enormous complexity of the climate system, the possibility is always there.

Another problem with models arises from the IPCC's practice of averaging model outputs. The idea is that by averaging multiple models, we should compensate for the shortcomings of each, and end up with a "best" prediction. Some will miss high, others low, and the result will probably end up closer than what any single model could have achieved on its own. The problem with doing this is that if none of the models work on their own, then it would seem that averaging them could only be providing the illusion of success. Again, this possibility is understood, and scientists try very hard to minimize it. But again, the possibility is there.

Another set of questions comes from an inability to accurately model small-scale phenomena when modeling larger climate systems. Climate models operate by dividing the climate system into "cells," where intracellular activity is only approximated, and intercellular activity is really what's being observed. If intracellular processes aren't being captured properly by the low-resolution approximations, then the result could be a butterfly effect in either direction. Small events which might have caused (or prevented) larger-scale phenomena would not be incorporated into the model, and the results could be game-changing. Modelers try to deal with this by running smaller-scale Regional Climate Models, but this problem is somewhat unavoidable given the limitations on computing power faced by climate modelers.

Yet another difficulty arises from the use of proscribed variables in models. Some processes are not well understood, and so they must be estimated outside the models and plugged in. As models become more complex, the proportion of internally calculated variables grows. But as long as we don't understand exactly how every piece of the puzzle works, this will continue to be a problem. Modelers often minimize the influence of this problem, though, by testing their models for their sensitivity to differences in proscribed values.

One last problem is that predictions are based on the assumption that the climate system will continue to behave as it has behaved in the past. Things like the the possible shutdown of thermohaline circulation or the collapse of the Greenland or Antarctic ice sheets would be game-changing, if they occurred, and would almost certainly add considerable uncertainty to our ability to make predictions. The roles of unquantified or undiscovered feedback mechanisms could also represent an instance of this problem.

All that being said, I don't think we can respond to uncertainty with inaction. I'm not sure who ought to bear the burden of uncertainty. But doing nothing places it all on the potential victims, which seems wrong in light of the fact that they'll never be able to obtain compensation, since those responsible will be long dead. Determining what we should do, though, is more complicated than I'd like to get into here. Hopefully that answer was helpful, and not too badly loaded with technical jargon. Feel free to ask for clarification!