Wednesday, November 4, 2009

Don't believe global warming scientists? Ask an economist

On the heels of my post yesterday which looked at what the Market believes about global warming (verdict: it's true and it's terrible), there's a new poll out today confirming that it's not just scientists who nearly unanimously buy the climate consensus: 84% of economists also agree that global warming poses significant risks to the economy. In the New York Times:

A New York University School of Law survey found near unanimity among 144 top economists that global warming threatens the United States economy and that a cap-and-trade system of carbon regulation will spur energy efficiency and innovation.

Outside academia the level of consensus among economists is unfortunately not common knowledge,” Richard Revesz, dean of the law school, said during a press conference Wednesday. “The results are conclusive – there is broad agreement that reducing emissions is likely to have significant economic benefits.”

The law school’s Institute for Policy Integrity sent surveys to 289 economists who had published at least one article on climate change in a top-rated economics journal in the past 15 years. Half of those economists responded anonymously to a dozen questions that solicited their opinions on a range of issues, from the impact of climate change on particular industries to how the benefits of reduced greenhouse gas emissions should be calculated.

The survey found that 84 percent of the economists agreed that climate change “presents a clear danger” to the United States and global economies – hitting agriculture the hardest – even though the severity of global warming remains unknown.

Only 5.6 percent disagreed with that statement while 7.6 percent were neutral and 2.8 percent had no opinion.

Interesting point #1: Agriculture will be the industry hurt most by global warming. To scientists, this isn't news. Anyone who follows climate science already knows that global warming will turn the Midwest into a permanent dust bowl of drought and decay. But it should be a wakeup call to agricultural interests and Midwestern Senators currently opposed to climate and clean energy legislation. Kansas Sen. Sam Brownback, for example, fears that cap-and-trade will hurt Kansas farmers by raising energy prices. Memo to Sen. Brownback: cheap energy doesn't help crops grow when there's no rain.

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Interesting point #2: Uncertainty increases, not decreases, the case for action NOW. Again, this is not news to anyone who follows climate science and economics. But the Superfreaknonomics authors, or the hack Jim Manzi over at, should take note of this:
Seventy-three percent of the respondents agreed that the uncertainty surrounding the severity of climate change raises the economic value of implementing measures to reduce greenhouse gas emissions.
The reason is simple: the costs of climate change range from large to civilization-destroying, while the worst-case costs of implementing cap-and trade look something like this. The economic crisis has taught us not to discount "long-tail" probabilities which, though unlikely to occur, would be almost too terrible to imagine if they did.

Interesting point #3: 98% of economists agree cap-and-trade will boost innovation and efficiency in the economy. This is a truly critical finding. Economics 101 teaches that economies grow not by keeping the price of goods cheap, but by inventing more products and producing them using fewer unit inputs. Unsurpisingly then, placing a price or cap on carbon would force companies to find ways of producing their goods using less energy, spurring a tidal wave of innovation and economic growth. And 92% of economists agree that market-based mechanisms like cap-and-trade are the best way to accomplish this goal. In fact, according to the poll, "most economists would support the cap‐and‐trade structure proposed by the main legislative options now pending before Congress."

So to the skeptic who thinks scientists are making up global warming: now you have two free market sources whose word you can take. Ask reinsurance company Munich Re, who believes climate change will be so destructive to property that they're pushing a $400 billion project to combat CO2. Or you can ask free market economists, 84% of whom believe global warming will damage the economy, and 98% of whom believe cap-and-trade will spur innovation and efficiency.


Don't believe in global warming? Ask an insurance company

Visualizing the "costs" of cap-and-trade


  1. And the reason that we should pay any attention to what economists think about climate science is ... ? I mean, do you believe what climate scientists say about economics?

  2. I agree. My point is simply that most climate skeptics start from the position that climate science is tainted by the peer review process or by the need for grant funding, thus dismissing out of hand all evidence as "biased." So for people who think scientists are hatching a socialist plot to destroy freedom, I thought maybe a more free market source would be more persuasive.

    Also, economists perspectives are somewhat relevant on issues like economic impact on agriculture, or the impact of uncertainty on the economic value of climate legislation.

    But yes, we can agree on the point that economists' opinions on climate science don't really matter.


  3. Thanks, WAG. The other issue, of course, is that the sample of economists is extremely biased. The study says:

    The Institute for Policy Integrity surveyed a group of the top economic experts on climate change to solicit their views on several key questions that affect climate change policy. The pool of economists was selected by searching the top twenty‐five economics journals over the past fifteen years and identifying all articles related to climate change. The roughly 300 authors of those articles were contacted and sent a survey, and more than half replied.

    Since an economist who doesn't think that warming will have much effect is less likely to be inspired to write about the dangers, and since "if it bleeds, it leads" is as true of economics as it is of newspapers, those who are convinced that warming=economic disaster are much more likely to have published papers on the subject.

    My best to you,


  4. Well that's tougher to prove. An economist who doesn't think global warming is happening could also be MORE inspired to publish a piece on cap-and-trade's ruinous effects on the economy.

    There's another issue here - if you surveyed all economists instead of just those who had published on global warming, you'd include in your sample a lot of people who had never studied the issue. That raises an interesting point: if you're trying to arrive at the Truth, what's more important: freedom from bias, or careful study of an issue?

  5. You raise an interesting point, WAG. If we are looking for knowledgeable opinions, what constitutes a "random sample" among people who have a variety of levels of knowledge on a subject. I'm not sure if this has an answer, even in theory.


  6. This post is a great example of the part-to-whole flaw. The title of this post makes it seem as though a general consensus was found among ALL ECONOMISTS, but it actually only showed data about "289 ECONOMISTS WHO HAD PUBLISHED AT LEAST ONE ARTICLE ON CLIMATE CHANGE IN A TOP-RATED ECONOMICS JOURNAL IN THE PAST 15 YEARS". The survey was carried out among an extremely small subset of economists and you can't reasonably project their opinions onto their larger parent group. You wouldn't do a survey of people who write blogs about crazy government conspiracies and conclude that their opinions are shared by all people.

  7. Actually, "part to whole" is not a flaw in this case. You're assuming that all economists have equally valid opinions on global warming. But why would you survey an economist who hadn't studied global warming for his views on the subject - or more accurately, why would their opinion matter?

  8. Great article you got here. You are most certainly correct, and this was also confirmed in recent surveys. Global warming affects all, even the economy. In some agricultural nations, the lack of rain is causing severe damage to crops. And for a nation dependent on agriculture, that's bad news.