Guest essay by Eric Worrall
The Age, an Australian newspaper, complains that economists who try to model the impact of climate change, say by measuring the impact of heatwaves, and scaling it up a little for the predicted increase in extreme weather, are not producing a high enough hypothetical body count to contribute properly to public discussion.
Economists are out of touch with climate change
If economists are to help us deal with global warming, they need to start studying science.
In the debate over climate change, there is one group from whom you don’t hear much: economists. The failure of climate economics to make a difference in the public discussion about climate policy should be a concern for the profession.
Climate economists are just as worried as anyone about the prospect of global warming. A recent survey by the Institute for Policy Integrity found that most climate economists believe climate change is a grave threat. Most supported carbon taxes or cap-and-trade programs to limit emissions, even if these actions were taken unilaterally by the United States. The consensus view was that a catastrophic loss of global gross domestic product – a 25 per cent decline or more – is possible under a “business as usual” scenario.
But for all this concern, economic research has had little impact on the public debate. The problem, as far as I can tell, is that there is a disconnect between climate science and economics. This goes beyond the out-of-date forecasting models used by policy makers. Even within academia, research often uses bad science.
The first climate economics paper I ever read provides a nice illustration of this problem. In 2007, Michael Greenstone, of the University of Chicago, and Olivier Deschenes, of the University of California-Santa Barbara, published a paper entitled “Climate Change, Mortality, and Adaptation: Evidence from Annual Fluctuations in Weather in the US“. The paper tried to estimate how many people would die as a result of global warming. To do this, the authors calculated how many people now die from random temperature fluctuations, due to things such as heat stroke. They then extrapolated this effect using the expected temperature increase from climate change, and found the probable increase in mortality is small.
Global warming will probably kill people in a lot more ways than days of extreme heat do now. If the climate changes a lot, floods will become more common in low-lying areas. Hurricane Katrina provided an example of how a large flood can cause a lot of deaths. This has nothing to do with the mechanism studied by Deschenes and Greenstone – the authors just leave it out. If they had paid more attention to science, they would have taken more sources of mortality into account.
The economists aren’t the only people confused by how a few degrees of warming is supposed to kill lots of people. In tropical Queensland, the Australian state where I live, which in rainy season is subject to violent weather extremes, a funny thing happened. When the government built the storm drains, the drain pipes they used are a little larger than other places where I have lived. That way, instead of backing up and flooding, the unusually large but planned for volumes of water from sudden tropical deluges are safely transported away from inhabited areas.
The high capacity drainage system doesn’t always work – planning mistakes have sometimes occurred, and truly enormous storm systems can occasionally exceed the carrying capacity of even Queensland drainage systems. But surely if such storm systems became more common, the drainage system would simply be scaled up even further, to accommodate changed weather patterns.
Most of the time, violent weather extremes are an inconvenience rather than a disaster, for regions with well designed and properly maintained civic infrastructure.