David Friedman on global warming
" "First, compare their credibility. One set of people have been arguing for 20 years ..."
As it happens, the passage of mine you quoted came from a blog post titled: " Global Warming, Nanotech, and Who to Believe." It dealt precisely with the question of deciding who to believe when one did not have sufficient expertise to judge all the arguments and evidence oneself.
Unfortunately for you, the argument about who to believe may not cut the way you want it to. The "set of people" arguing for drastic actions to reduce global warming correlates pretty well with the set of people who have been warning against a variety of other environmental catastrophes for considerably more than twenty years--the people who took seriously _Limits to Growth_ and predictions of global famine to occur in the 1970's and racked up, over the past forty or fifty years, a string of false predictions unmatched outside of the nuttier end of the world sects.
It isn't wholly unreasonable, when we observe such people converting a three foot rise in sea level over a century into rhetoric about mass flooding of large parts of the inhabited world, or blaming a New Orleans flood that has been predictable (and predicted) for decades on global warming that has, so far, raised sea levels by a few inches, to suspect that something is going on other than objective science.
So far as my position is concerned, the theoretical argument for anthropogenic global warming struck me as plausible from the beginning. I don't think I've been commenting on the subject for as long as twenty years, but my general view, so far as I can recall, has always been that it was a plausible conjecture but that people pushing the idea tended to overstate how strong the evidence was and how large the effects were likely to be. That's the same attitude reflected in the comment of mine you quoted.
So far as the implications are concerned, if global warming is going to have relatively small effects, then it is not worth bearing very large costs to prevent it.
Anyone interested in a more detailed account of my views may want to look at the post of mine you linked to, some of the other recent posts on my blog that dealt with the issue, and the discussion that followed. "
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"Eli argues that "in addition to the politically active environmental groups essentially the whole climate science community has been aware of the issue for 20 years and crossed the threshold to recognizing the seriousness of the threat 10 years ago."
I think he is confusing agreement on the existence of global warming with agreement on its scale and consequences. If he checks the links in my post, referenced in the post I was responding to here, he will find two of the scientists responsible for parts of IPCC reports on hurricanes disagreeing with the alarmist view. One of them eventually resigned in protest against the attempt by the lead author of the section he was supposed to be writing part of to misrepresent the current state of scientific knowledge in the field.
Eli (and Mike Huben) also want to claim that the reasons why predictions of environmental catastrophe didn't come true was the response to those predictions. I suggest a simple exercise--read _Limits to Growth_ and Paddock and Ehrlich's predictions of world famine to occur in the mid-seventies. In both cases, the claim was not "if we don't do something, bad things will happen." It was "catastrophic things are going to happen whatever we do, our only choice has to do with how bad the catastrophe will be."
As with other end of the world cults, one can always explain away the failure of the world to end--after discovering that it didn't.
Jeff disputes my claim that the intellectual justification for the large expansion in government power from about 1930-1970 has collapsed, writing (in part):
"Yeah, I know I sure want to go back to those good old days of 1929-1930!"
In 1960, the generally accepted view of economists was that the Great Depression was the result of the inherent instability of capitalism, hence implied the need for government intervention. We now know that that conclusion was based on an incorrect reading of the historical facts, that the Federal Reserve System, having been set up to prevent things like the Great Depression from happening, in fact was a major cause of its happening. Hence the desire to avoid depressions no longer provides intellectual justification for expanded government power.
It's true that changes in the views of economists don't result in instant changes in public opinion; as Jeff demonstrates, public opinion in economics as in other fields has a tendency to lag behind professional opinion. And people in general are naturally conservative, in the literal sense of the term, and so tend to take for granted the institutions they grew up with--which currently means the post-New Deal system of big government.
Nonetheless, those who want more of that instead of less of that, and observe even a Democratic President claiming to be against "big government," would naturally like some new arguments to replace the old ones.
Finally, I note that not one of the responses here, including the original post, dealt with the substantive arguments in the post on my blog that started this discussion. If the upper end of the predicted range for the rise in sea level is 80 cm by the year 2100--the current IPCC figure--and if the predicted effect on hurricanes is no change in frequency and only a slight increase in magnitude (see the links from my blog), how do you justify the view that global warming can be confidently expected to produce catastrophic consequences and it is therefor worth bearing large costs now to slow it?"
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"At a slight tangent ... .
One of the commenters makes the argument that taking precautions against global warming is sensible even if it probably isn't a big problem, because it might be. The difficulty with this argument is that playing safe isn't really an option. Most obviously, "precautions" on the scale that are being urged could do substantial damage by slowing the economic development that has been improving the lives of people in poor countries. And it's even possible, although not I think likely, that it would push climate in the wrong direction, that global warming is what is keeping us from the next ice age.
One way I like to put the general point is by arguing that the precautionary principle is one of the chief causes of global warming. It is the precautionary principle, although not under that name, that is largely responsible for the slow rate of introduction of nuclear power, the argument being "unless you are absolutely certain nothing terrible will go wrong, don't do it--play safe." And nuclear power is the one alternative to fossil fuels that, with current technology, can be scaled up more or less without limit.
Going back to my initial point about the ways in which people's general ideological views bias their conclusions on specific issues like this, it's worth noting how little support there has been among people worried about global warming for increasing use of nuclear power. It seems an obvious implication of their position on global warming--but it's one sharply inconsistent with the more general ideology that, for many of them, helps motivate that position."
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"To get back to a point in the original post:
"Finally, Friedman didn't define anything. How many Bangladeshis have to die from increased storm intensity with increased sea levels to make it "catastrophic", or how many African children die from reduced subsistence farming productivity?"
Suppose precautions against global warming slow the economic growth rate of Bangladesh by one percentage point. How large would the resulting excess mortality be over the next century? Is there any serious doubt that it would be larger than the excess mortality from an 80 cm rise in sea level over the same period, combined with a 5% increase in the average strength of hurricanes? Poverty kills a lot more people than flooding does.
To put it differently, I suspect that your view here is partly driven by the unstated assumption that the things you want people to do to reduce global warming are things that ought to be done anyway--that there really is no cost. Once you drop that assumption, which you cannot expect the rest of us to share, we are talking about precautions that are likely to be very costly in human terms, and so justified only if they prevent a major catastrophe.
And, of course, global warming, like most changes, can be expected to produce benefits as well as costs. CO2 is an input to photosynthesis, after all, so you want to allow for the African children who will die as the result of keeping CO2 levels down as well as the ones who will die from letting it go up. I doubt you have the data to estimate the sign of the net effect--certainly I don't."
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" "Well, let's see:
David is pointing to Landsea (who isn't really a denialist and only focuses on one issue) and I think the other is Lindzen, who's discredited. I'll take the thousands of scientists on the other side of the IPCC."
I realize that choosing my authorities for me makes it easier for you to refute them; where in the discussion on my blog did I cite Lindzen? Since I cited Landsea's figures on the predicted effects of hurricanes--his field--I'm not sure how "he's not a denialist" is relevant.
If "denialist" includes anyone who does not think the evidence supports the claim that global warming is going to cause large increases in the strength, frequency, or both of hurricanes, then he is a denialist; if that isn't what you mean, then I'm not.
The question is what reasonable estimates are for the size of the effects of global warming--and on that question the closest anyone responding to me in this thread has come to an argument has amounted to "there might be much larger effects than the IPCC figures predict." (not a direct quote).
I agree that there might be--climate is clearly not yet a well understood subject. But the claim that is being made by your side of the argument, over and over, is that the scientific consensus holds that very bad things are going to happen. That claim is false. You can't support it by saying "the scientific consensus cannot eliminate the possibility that very bad things might happen."
I'm glad that you agree that the environmentalists greatly overestimated the consequences of the problems they were writing about. You seem unwilling, however, to engage on the question of whether the same thing is happening here. As I keep repeating, the upper limit of the IPCC estimate is 80 cm. by 2100. Yet the rhetoric of the movement implies effects, predictable not merely conceivable, easily an order of magnitude larger than that--consider, for instance, the piece I quoted in the first of my blog posts on the subject. Do you disagree?
I should add that, in the case of _Limits to Growth_, the fundamental problem wasn't bad environmental science but bad economics. As best I can recall from conversations at the time, I did not encounter a single economist who took it seriously--because it consistently ignored the effect of rational choice by the people affected, which is what economics is about. It was as if someone had tried to extrapolate the behavior of automobiles on the highway while implicitly assuming that all of the drivers had their eyes closed.
Yet the environmental movement took it seriously--because it reached the conclusions they wanted. "
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" "Upending the climate status quo is almost certain to be net negative - people have adjusted to the status quo, and they're not adjusted to whatever the new, constantly changing climate situation will be."
That's a legitimate point. I agree that, all else being equal, change is more likely to make things worse than better, because people have adjusted their lives to current circumstances.
But the strength of that argument depends very much on the speed of the change. A sea level rise of 80 cm in a year would impose quite serious costs. A sea level rise of 80 cm in a century, which is what the IPCC is talking about, means that new construction happens a little farther from the coast, that particularly vulnerable areas dike, as the Netherlands did a very long time ago, that the pattern of what crops are grown where shifts a bit.
Even without global warming, that sort of thing is going to happen--do you seriously believe that the crop strains people will be planting in 2100 will be the same ones they are planting now? In the case of a not very large change occurring slowly in a society already changing in a variety of other ways, the presumption that change imposes net costs becomes very weak.
Look at your own rhetoric: "Upending the climate status quo." Think about an 80 cm rise over a century or a five percent increase in hurricane strength over 70+ years and see if you can still use that phrase with a straight face."
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