The Future: six drivers of global change Part 136

169 theories for why global warming is causing a shift in the Hadley cells

Lu et al., "Expansion of the Hadley Cell Under Global Warming."

170 the difference in average temperatures

Jennifer Francis and Stephen Vavrus, "Evidence Linking Arctic Amplification to Extreme Weather in Mid-Lat.i.tudes," Geophysical Research Letters 39 (2012).

171 The widening of the Hadley cells

Lu et al., "Expansion of the Hadley Cell Under Global Warming."

172 on the edge of persistent water shortages anyway

Personal communication with Dargan Frierson, May 25, 2012.

173 human alteration of the same natural climate feature

Rudolph Kuper and Stefan Kropelin, "Climate-Controlled Holocene Occupation in the Sahara: Motor of Africa's Evolution," Science, August 11, 2006.

174 barrel loop atmospheric currents known as the Ferrel cells

National Oceanic and Atmospheric Administration, "JetStream-Online School for Weather," October 2011, http://www.srh.noaa.gov/jetstream/global/circ.htm.

175 pulling cold Arctic air southward in winter, and disrupting

Frances and Vavrus, "Evidence Linking Arctic Amplification to Extreme Weather in Mid-Lat.i.tudes."

176 begun to produce a slight thinning of ozone

U.S. Environmental Protection Agency, "Environmental Indicators: Ozone Depletion," August 2010, http://www.epa.gov/ozone/science/indicat/index.html.

177 dangerous ozone hole above the Arctic might form on a more regular basis

Tim Flannery, Here on Earth: A National History of the Planet (New York: Atlantic Monthly Press, 2010), ch. 14, "The Eleventh Hour?"

178 interacting with the unique atmospheric conditions

Mario Molina and Sherwood Rowland, "Stratospheric Sink for Chlorofluoromethanes: Chlorine Atomic Catalyzed Destruction of Ozone," Nature, June 28, 1974.

179 radiates the reflected sunlight back into s.p.a.ce more powerfully

Australian Government, Antarctic Division, "Environment-Land, Sea and Air," http://www.antarctica.gov.au/about-antarctica/fact-files.

180 like Australia and Patagonia to high levels of ultraviolet radiation

J. Ajti et al., "Dilution of the Antarctic Ozone Hole into Southern Midlat.i.tudes, 19982000," Journal of Geophysical Research 109 (2004).

181 when air with low concentrations of ozone is no longer able

Ibid.

182 injecting water vapor in the stratosphere

James Anderson et al., "UV Dosage Levels in Summer: Increased Risk of Ozone Loss from Convectively Injected Water Vapor," Science, August 2012.

183 the Earth's atmosphere attempting to maintain its energy "balance"

V. Ramaswamy et al., "Anthropogenic and Natural Influences in the Evolution of Lower Stratospheric Cooling," Science 311, no. 5764 (February 24, 2006): 113841.

184 "Some say the world will end in fire; some say in ice"

Robert Frost, "Fire and Ice," Harper's Magazine, December 1920.

185 "future decades if industrial fuel combustion continues to rise exponentially"