David R. Henderson  

Reply to Scott Sumner on Global Warming

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Scott Sumner writes:

I recall that when liberals favored lots of "command and control" regulation to address global warming, and conservatives favored a carbon tax. That was the "market solution" comparable to the market-based approach to reducing sulfur emissions from coal-fired power plants. Some conservatives now latch on to "contrarians" in the scientific community. OK, but how come when the shoe was on the other foot conservatives would talk about "scientific consensus." For instance, conservatives used to criticize a lot of the excessive regulation of chemicals in the environment, by pointing to scientific studies that showed many of the pollutants that environmentalists were obsessing about did not have a statistically significant impact on health. When I read the Wall Street Journal in the 1970s it seemed like it was the clear thinking conservatives relying on science vs. the muddy-headed romantic environmentalists.

As Scott knows, I am not a conservative, but I couldn't help but think that he was criticizing libertarians also when those libertarians oppose a carbon tax. On the assumption that Scott is including libertarians, here's my response:

It's hard to talk about an amorphous group when Scott doesn't name or otherwise identify any of them, other than to call them "conservatives." So I'll speak for myself.

I still criticize much regulation of chemicals in the environment and it's true that I point to "scientific studies that showed many of the pollutants that environmentalists were obsessing about did not have a statistically significant impact on health." I don't recall, though, that I've talked about "scientific consensus." I have remained open to other scientific studies. What I have not done is put the same weight on the views of an environmentalist with no scientific standing as I have on the views of a scientist who is informed about the issue.

I do the same with global warming. There was a statement years ago, signed by about 31,000 people, claiming that global warming is not a big deal. Various people quoted it, claiming that it was signed by thousands of scientists. It's possible that it was. But I didn't have the time to do due diligence on the names of the signers and so I have never quoted it.

Also, even if I were to talk about "scientific consensus" as a shorthand when I want to talk about a scientific issue in which I am not expert (which is the vast majority of them), I would not dismiss criticisms or objections on the grounds that they challenge the consensus. I would definitely not refer to those who disagree as "deniers."

Later in his post, Scott has anticipated one of the defenses, writing:

A note to commenters. Before you mention some study that has the support of 5% of climate scientists, ask yourself how you'd feel if some massive liberal big government intervention was being proposed on the basis [of] studies that 5% of scientists supported, and 95% thought were nuts. Wouldn't you ridicule the heterodox view?

My answer is "No, I wouldn't ridicule the heterodox view. I would consider the reasoning and try, as best I could, to examine the evidence."

But where does Scott get the 5%? He doesn't say. I have written here and here, as has David Friedman here and here, about the suspect nature of the claim that 97% of scientists believe that global warming is caused mainly by humans.

Notice, though, a little irony. Why did Scott start blogging and what is he best known for? For arguing that the Federal Reserve should target nominal GDP and that its failure to do so was the main factor responsible for the 2007 to 2009 Great Recession. In a survey of business economists, what percent of them agreed with his view that monetary policy had been too tight? As Scott points out, it was 6.6 percent, which is uncomfortably close to his 5% number.

Does this cause Scott to doubt his own views? No, it doesn't. Now there is a difference here that Scott could reasonably argue is important. The difference is that Scott is an expert on monetary policy in a way that I am not on global warming.

But if Scott held the same standard for other people, he would have to argue that non-experts on monetary policy should pay his views little or no heed. How about it, Scott. Would you?

Note: Bob Murphy has covered some of the same ground here.


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COMMENTS (18 to date)
Robert Wiblin writes:

Presumably Scott does think there's a decent chance he is wrong about monetary policy. To think otherwise would be to not take peer disagreement seriously, which is just foolish.

However, Scott may also think he furthers knowledge and his own interests more effectively by making the best case he can for his unusual conclusions, even if his 'all things considered' view of the evidence is much less certain.

http://philreview.dukejournals.org/content/122/3/395.abstract

ThomasH writes:

It think it is silly to quibble over whether Scott's criticisms of "Conservatives" opposition to carbon taxes includes "Libertarians" of not. Carbon taxation, like any Pigou tax, is compatible with "Libertarian" principles as I understand them. And application of Pigou taxation depends on a (consensus) scientific understanding of the physical externality that is being taxed. Of course any specific proposal for a carbon tax is unlikely to be a pure Pigou tax and so Liberals and Libertarians may be skeptical about it on public choice or efficiency grounds.

S.C. Schwarz writes:

Unless he has worked very hard to study the issue, Scott Sumner doesn't know what the true consensus is on CAGW because dissent from the mainstream view has been ruthlessly suppressed.

Felipe writes:
But if Scott held the same standard for other people, he would have to argue that non-experts on monetary policy should pay his views little or no heed. How about it, Scott. Would you?

I think he does:

If the Fed had done what was necessary to prevent the Great Recession, they would have had to move far out of the mainstream. As it was, their views were already better than average. It is simply unrealistic to expect a major conservative institution to take radical positions on important public policy questions. I'm not even sure it's desirable for powerful institutions to make radical decisions. Instead, we need to fix the economic profession, so that economists as a group favor monetary policy regimes that provide slow and steady growth in nominal spending.
magilson writes:

It's incredibly "easy" to oppose a carbon tax even if it is both the most logical and economically reasonable way to deal with such an externality AND also compatible with libertarian ideals.

I cannot, as a sane person, support a tax proposed by the very same group of people who constantly set a tipping point date of no return which is constantly kicked down the road as model after model after prediction after prediction do not ever in any way come to pass.

1. If it's too late why cause economic suffering in addition to environmental suffering.

2. If you cannot make one single accurate prediction about any aspect of global whatever's consequences why should any reasonable person feel comfortable that you'll get the price correct?

3. If we explain away #2 by suggesting a market place my follow up question is how well is that working for the EU? My opinion is not well by any measure.

4. Given the rest please do spend some time considering that dealing with global whatever might be easier than trying to stop global whatever. And I would love to be convinced the dealing with it part will be best accomplished by a tax imposed in the name of preventing it. Once that political ship sails it's never going to change it's course, in my opinion.

5. The final "nail in the coffin" for my confidence in anything involving global whatever was just how long it took the "scientific community" to grasp the obvious mathematical truth of The Pause since now it's being accepted and studied by more than just the "denialists". It's sort of hard to swallow Authoritarianism from a group of actual denialists when their first order of business for these researchers and scientists is name calling the opposition as "denialists". And yes I'm aware of what I just did there.

David R. Henderson writes:

@ThomasH,
It [sic] think it is silly to quibble over whether Scott's criticisms of "Conservatives" opposition to carbon taxes includes "Libertarians" of not.
I trust that you read the whole piece and realize that my “quibble” is a small part of my post.

John Goodman writes:

Matt Ridley summarized mainstream thinking and evidence on this question in the WSJ a few days ago: http://online.wsj.com/articles/matt-ridley-whatever-happened-to-global-warming-1409872855

The UN Panel on Climate Change expects a 0.5 degrees temperature increase in the next 30 years. Even if that happens, it won't be the end of the world.

And that estimate has to be considered in the light of a long pause (of no warming) over the past 16 to 26 years -- depending on the measurement.

Since there are a number of economist weighing in here, it would do us all good to review David Henderson's (cost benefit) case for watchful waiting: http://healthblog.ncpa.org/how-much-should-we-worry-about-global-warming/

Scott Sumner writes:

David, You asked:

"But if Scott held the same standard for other people, he would have to argue that non-experts on monetary policy should pay his views little or no heed. How about it, Scott. Would you?"

Yes, unless they felt they were qualified to evaluate my arguments. Felipe has a comment (above) that expresses my views.

BTW, I have read many scientific papers on global warming. I don't consider it a sure thing, but it seems very likely to me that the theory is broadly correct.

The fact that liberals and conservatives (plus libertarians) have radically different views on the science of global warming suggests that bias is a huge problem in evaluating scientific evidence. However it does not imply the problem is with conservatives. It's possible that liberals are biased. Or both sides. But definitely not neither side. I hope we can all agree on that point. There is an enormous problem of cognitive bias---somewhere.

Andrew_FL writes:

It strikes me that the original statement, that the left and right have been moving apart without good reason, assumes there was good reason for them to be close together in the first place.

Seems to me that for two parties (which seems to be what Sumner really means by "conservative" and "liberal" because that's the only way it makes sense to me. Happy to be corrected) fail to serve an electorate of diverse views, by agreeing on everything. Seems to me only natural and right that their views should diverge.

I would otherwise raise much the same point for myself of attributing by implication the opinions and positions of a group writ large to individuals self styled to belong to an ideologically congruent (on said issue) group (or in my case, the imputed group). I have never appealed to scientific consensus, only to scientific evidence, to question in both cases the position favoring government action to solve an alleged problem.

As to the above suggestion that a Pigouvian is "libertarian" or not, it is not as I understand libertarianism. To my understanding, forced to accept the premise that there is a "problem" of Global Warming, I understand the libertarian view to see it as a problem best addressed through the legal avenues to protect property.

To Scott's point about the theory being "broadly correct" there is a very large gap between "the theory"-presumably that there is some warming, caused primarily by humans-and there being a problem that requires any sort of solution whatsoever.

MikeP writes:

Carbon taxation, like any Pigou tax, is compatible with "Libertarian" principles as I understand them.

That's debatable, but I'll accept it for the sake of argument.

And application of Pigou taxation depends on a (consensus) scientific understanding of the physical externality that is being taxed.

A scientific understanding of the externality is indeed necessary, but it is not at all sufficient. An economic understanding of the costs of the externality -- as well as an economic understanding of the costs of the proposed alternative -- is also necessary.

And those who call for taxing carbon dioxide lack the economic understanding in spades.

RHolt writes:

This just struck me as insanely funny and quite apropos.

"There is an enormous problem of cognitive bias---somewhere."

Kevin Dick writes:

@Scott. I've read a lot of papers on the topic too and I think they've got the sign correct but the magnitude vastly overestimated. Care to make a wager?

I make this offer by way of illustrating that given your fondness for an NGDP futures market (a fondness I share), surely what you should be advocating for is a temperature index futures market :-)

Prakash writes:

Kevin,

You took the words away from my mouth. One part where I agree with Robin Hanson is his support of prediction markets. They do act as a test for everyone to put their money where their mouth is.

Lets have prediction markets for temperatures, ocean ph and all the factors that are truly important in the global warming debate. infact hanson is doing that with scicast.

Daublin writes:

As magilson writes, it's easy to oppose carbon controls even if you accept the science as IPCC describes it.

Most centrally, the IPCC has always claimed that to eliminate CO2 as a cause for temperature to increase, human emissions need to be about half of what they were in 1990. It's worse than that, though, because in 1990, much of the world was not well industrialized. If we think that China and India deserve to partake of automation just like more industrialized areas, then the currently industrialized areas need to reduce emissions by around a factor of 10, so as to allow China and India to get a fair share of their own emissions. This is the core scientific result that is relevant for carbon controls.

Reducing emissions by 90% is bound to be very painful. We need emissions to have cheap energy, and we need cheap energy to enjoy modern life as we know it. We should only accept such a severe change if we are pretty sure that the alternatives are just awful.

At the same time, if you accept the science, then a reduction of 10% makes a negligable difference. So long as CO2 is above the replacement level, it will continue to grow, so all a 10% reduction will do is delay the inevitable. Yet, almost all current policy is aimed at these incremental reductions that have no hope of making a real difference. Windmills and electric cars are a complete waste of time, at least if you believe the IPCC.

I will stop there, with just an outline of the argument. As much as I believe Michael Mann and Phil Jones deserve approbation for scientific misconduct, I believe the problems with carbon control are more fundamental.

Don Watkins writes:

I think the real issue is how we ought to use experts: as guides to help us think through issues or as authorities. By itself, the fact that X% agree that the earth is warming tells us very little. We would have to ask:

*What are the basing that conclusion on? For instance, climate models? How successful have those models been at predicting climate?

*What exactly are they agreeing on? That the earth will continue to mildly warm? Or that the warming will be catastrophic?

*What are they truly experts on? For instance, if they are experts on, say, paleoclimatology, does that put them in a position to make pronouncements about climate science overall? Does it make them experts on the political and economic policies they advocate to fight climate change?

There are many more such questions we need to ask. Experts are vital, but their role is not to hand down "the truth," which we then must accept on faith.

Mark Bahner writes:
Lets have prediction markets for temperatures, ocean ph and all the factors that are truly important in the global warming debate. infact hanson is doing that with scicast.

I proposed something similar, but with a large monetary prize going to universities in the fairly distant future (20+ years from now). The reason for giving the money to universities is that they're nearly immortal. (At least so far.)

A method for achieving honest climate predictions

Theodore Sternberg writes:

I'm generally favorably inclined to market solutions, but I object to the idea of the government setting up a market in "carbon contracts" because I don't care for the implied initial allocation -- that the government owns the air and gets to make us pay for it.

You should shorten this post, by the way; it reads like a petty verbal slap-fight and does you (Henderson) no credit.

Peter writes:

You can be against a carbon tax or other measures on the grounds that the tax will not have any effect on the problem because the CO2 producing activities move to other countries.

You can also say that the really important question is the future temperature and the claims about that are merely theories supported by computer models that are clearly struggling to work well.

You can also say that there are climate science experts who clearly do not support the more worrying claims about the future, or the claimed certainty about those claims.

Also, even if the worst claims are true, it does not follow that money spent on emissions reduction is a good idea. And that is not a question within the expertise of climate scientists.

So, I don't think Scott made his case.

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