Costs of Climate Change

The Jan 9, 2009 issue of Science contains a paper (p. 240) and a commentary (“Higher Temperatures Seen Reducing Global Harvests”, p. 193) on the effects of climate change on agricultural yields. An atmospheric scientist, David Battisti (U. Washington, Seattle), and an economist, Rosamond Naylor (Stanford U., Palo Alto), analyzed predictions from 23 climate models used by the IPCC to figure out what might happen to agricultural yields by the end of this century.

“Their conclusions with regard to agriculture are sobering. “In the past, heat waves, drought, and food shortages have hit particular regions,” says Battisti. But the future will be different. “Yields are going to be down every place.” Heat will be the main culprit.” (emphasis added) Additional support comes from past observations. A heat wave struck France in summer 2003 and “the country’s corn and fruit harvests fell more than 25%.”

At the same time that agricultural yields might be falling, scientists expect to see a rise in global populations, a rise in demand for meat, and a rise in demand for water. If all of these trends collide, food costs could eat up a much larger fraction of the average person’s paycheck in developed countries, and food scarcity will affect many more people in developing countries.

To avoid these problems, we need to act now. Scientists need to develop new heat-resistant crop varieties and citizens, politicians, and scientists need to figure out ways of limiting the degree of climate change.