Strategies for Slowing Global Warming

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Science  08 Sep 2000:
Vol. 289, Issue 5485, pp. 1655
DOI: 10.1126/science.289.5485.1655a

The large and rapid atmospheric warming of the twentieth century, which few now doubt can be explained without invoking anthropogenic forcing, is thought to be mostly the result of the buildup of trace greenhouse gases in the atmosphere. Although carbon dioxide has received the most attention, an equal amount of heat is trapped in the atmosphere by the combined effect of the other four principal trace greenhouse gases: Methane, chlorofluorocarbons (CFCs), tropospheric ozone, and nitrous oxide.

Hansen et al. argue that instead of constructing strategies for mitigating global warming that rely mostly on reducing carbon dioxide emissions, a more expedient approach would be to reduce emissions of the other greenhouse gases and black soot (a product of coal and diesel fuel combustion). Methane emissions could be reduced by modifications in agriculture, animal husbandry, coal mining, oil drilling, and waste management. Decreasing soot and ozone would confer large positive benefits for human health. None of these actions would imperil economies that depend on energy use, and their adoption would allow more time for the development of more fuel-efficient technology and renewable energy sources. Significantly slowing the trend of global warming probably will require burning less fossil fuel, although these other methods should help slow the rate of anthropogenic climate change over the next half century until the better energy technology has been developed. — HJS

Proc. Natl. Acad. Sci. U.S.A., in press.

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