Thursday, July 19, 2007

Nobelist weighs in: Kenneth Arrow on climate change

An economics blog called Oikos links to the latest issue of The Economists' Voice, with an article on the economics of climate change. Oikos calls it: excellent primer on climate change by Kenneth Arrow: Global Climate Change: A Challenge to Policy. I'd really recommend reading it as a backgrounder to the issue:

[Arrow says that] Two factors deserve emphasis, factors that differentiate global climate change from other environmental problems. First, emissions of CO2 and other trace gases are almost irreversible; more precisely, their residence time in the atmosphere is measured in centuries. Most environmental insults are mitigated promptly or in fairly short order when the source is cleaned up, as with water pollution, acid rain, or sulfur dioxide emissions. Here, reducing emissions today is very valuable to humanity in the distant future.

Second, the scale of the externality is truly global; greenhouse gases travel around the world in a few days. This means that the nation-state and its subsidiaries, the typical loci for internalization of externalities, are limited in their remedial ability.

The detail in the article is on the issue of discounting future costs, which is central to the findings in the Stern Report on The Economics of Climate Change that susbstantial immediate action on climate change is likely to be much cheaper over the long-term than inaction. Discounting is something I need to cover in a future Oikos 101 column, but for now I'll just observe that Stern has been criticised for using a zero rate of pure social time preference - which is consistent with the idea of inter-generational equity but inconsistent with observations by economists of how people actually behave.

Arrow conducts a sensitivity analysis, plugging different social time preference rates into Stern's figures, and finds that using a higher social time preference rate doesn't change the fundamental finding of the Stern Report, that action will cost less than inaction…

[The post at Oikos includes a discussion of a climate article by Thomas Schelling, too]

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