Multiple models of near-future climates predict the southwestern United States will become even hotter and dryer over the next century. This inevitably raises the question of whether the current drought is caused by global warming.
Two PNAS studies consider this question, and say that it's not possible to make a definitive attribution. The current drought fits historical patterns. Past droughts also seem linked to cooling patterns in Pacific Ocean surface temperatures, and the eastern Pacific has indeed been cooling since the late 1970s.
Image: Historical records of southwestern water flow./PNAS
Citation: "Future dryness in the southwest US and the hydrology of the early 21st century drought." By Daniel R. Cayan, Tapash Das, David W. Pierce, Tim P. Barnett, Mary Tyree, Alexander Gershunov. Proceedings of the National Academy of Sciences, Vol. 107 No. 50, December 14, 2010.
Citation: "Greenhouse warming and the twenty-first-century hydroclimate of southwestern North America." By Richard Seager, Gabriel A. Vecchi. Proceedings of the National Academy of Sciences, Vol. 107 No. 50, December 14, 2010.
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