The World in 2050_ Four Forces Shaping Civilization's Northern Future - Laurence C. Smith [154]
267 P. Alpert et al., “First Super-High-Resolution Modeling Study that the Ancient ‘Fertile Crescent’ Will Disappear in This Century and Comparison to Regional Climate Models,” Geophysical Research Abstracts 10, EGU2008-A-02811 (2008); A. Kitoh et al., “First Super-High-Resolution Model Projection that the Ancient ‘Fertile Crescent’ Will Disappear in This Century,” Hydrological Research Letters 2 (2008): 1-4.
268 T. H. Brikowski, “Doomed Reservoirs in Kansas, USA? Climate Change and Groundwater Mining on the Great Plains Lead to Unsustainable Surface Water Storage,” Journal of Hydrology 354 (2008): 90-101; S. K. Gupta and R. D. Deshpande, “Water for India in 2050: First-Order Assessment of Available Options,” Current Science 86, no. 9 (2004): 1216-1224.
269 Global climate models almost unanimously project that human-induced climate change will reduce runoff in the Colorado River region by 10%-30%. T. P. Barnett., D. W. Pierce, “Sustainable Water Deliveries from the Colorado River in a Changing Climate,” Proceedings of the National Academy of Sciences 106, no. 18 (2009), DOI:10.1073/pnas.0812762106. See also T. P. Barnett D. W. Pierce, “When Will Lake Mead Go Dry?” Water Resources Research 44 (2008), W03201.
270 This is not necessarily so dire as it sounds. Water rights are about withdrawals, not consumptive use, so some share of the withdrawn water is recycled and returned to the river system, allowing it to be reused again downstream.
271 J. L. Powell, Dead Pool: Lake Powell, Global Warming, and the Future of Water in the West (London: University of California Press, 2008), 283 pp.
272 The 2003 pact, called the Quantification Settlement Agreement, also requires the Imperial Irrigation District to sell up to 100,000 acre-feet to the cities of the Coachella Valley. California’s total Colorado River allocation is 4.4 million acre-feet per year. The Metropolitan Water District of Southern California serves twenty-six cities. Press releases of the Imperial Irrigation District, November 10, 2003, and April 30, 2009 (www.iid.com); also M. Gardner, “Water Plan to Let MWD Buy Salton Sea Source,” Union-Tribune, signonsandiego.com, April 6, 2009.
273 Unlike water vapor, which is quickly recycled, other greenhouse gases tend to linger longer in the atmosphere, especially CO2, which can persist for centuries. S. Solomon et al., “Irreversible Climate Change Due to Carbon Dioxide Emissions,” PNAS 106, no. 6 (2009): 1704-1709. About half will disappear quite quickly and some 15% will stick around even longer, but on balance carbon dioxide persists in the atmosphere for a very long time.
274 More precisely, volcanic eruptions release sulfur dioxide gas (SO2), which oxidizes to sulphate aerosols (SO4). If aerosols penetrate the stratosphere, they can circulate globally for several years, creating brilliant sunsets and blocking sunlight to create a temporary climate cooling.
275 Some of these mechanisms can persist for several decades, especially long-lived ocean circulation phenomena like the Pacific Decadal Oscillation, e.g., G. M. MacDonald and R. A. Case, “Variations in the Pacific Decadal Oscillation over the Past Millennium,” Geophysical Research Letters 32, article no. L08703, DOI:10.1029/2005GL022478 (2005).
276 By averaging model simulations over a twenty-year period (2046-2064), this map smooths out most of the short-term variability described earlier, thus revealing the strength of the underlying greenhouse effect. Yet even after this smoothing process, we still find a geographically uneven pattern of warming. For map source see next endnote.
277 IPCC AR4, Figure 10.8, Chapter 10, p. 766 (Full citation: G. A. Meehl et al., Chapter 10, “Global Climate Projections,” in S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis,