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Science  20 Oct 2006:
Vol. 314, Issue 5798, pp. 387d
DOI: 10.1126/science.314.5798.387d

Earth's climate is warming, and carbon dioxide emitted from the burning of fossil fuel is very likely to be the major cause. Global temperatures are projected to rise above preindustrial values by 1.5° to 5.8°C by the end of the 21st century. The search is on for ways to slow warming, potentially by large-scale climate geoengineering.

One possible approach to this risky endeavor is to inject sulfate precursors into the stratosphere (see Wigley, Reports, 20 October 2006, p. 452), because sulfate aerosols reflect sunlight and would have a consequent cooling effect. In an attempt to lay the foundation for a more thorough discussion of climate geoengineering options Crutzen discusses the theoretical basis, possible methodologies, and advantages and disadvantages of such a scheme. Five other authors (Cicerone, Kiehl, Bengtsson, MacCracken, and Lawrence) weigh in on the history of such proposals, the practical as well as ethical considerations of various approaches, and how best to evaluate different geoengineering schemes. The authors make it clear that geoengineering climate is a less desirable potential solution to warming than controlling greenhouse emissions, and that only if warming causes sufficiently harmful impacts would geoengineering be a better choice. — HJS

Clim. Change 77, 211; 221; 227; 229; 235; 245 (2006).

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