Ibid.

72 thirty-seven such megacities will sprawl across the Earth

Ibid.

73 a projected increase of 175 percent between 2000 and 2030

United Nations Population Fund (UNFPA), State of World Population 2007: Unleashing the Potential of Urban Growth, http://www.unfpa.org/swp/2007/english/introduction.html.

74 from 11 million today to just under 19 million in 2025

United Nations Department of Economic and Social Affairs, "World Urbanization Prospects: The 2011 Revision."

75 projected to have a population of almost 33 million people by 2025

Ibid.

76 By 2050, almost 70 percent of the world's population will be city dwellers

Ibid.

77 roughly one out of every three inhabitants of cities

Most of us have an image of what a "slum" is, but in fact slums come in different shapes and sizes. What they share in common, according to the United Nations definition: "lacking at least one of the basic conditions of decent housing: adequate sanitation, improved water supply, durable housing or adequate living s.p.a.ce." UNFPA, State of World Population 2007: Unleashing the Potential of Urban Growth.

78 two billion people within the next seventeen years

Ben Sutherland, "Slum Dwellers 'to Top 2 Billion,' " BBC, June 20, 2006, http://news.bbc.co.uk/2/hi/in_depth/5099038.stm.

79 growing at a rate even faster than the overall urban growth rate

United Nations Department of Economic and Social Affairs, World Population Monitoring: Focusing on Population Distribution, Urbanization, Internal Migration, and Development, 2009.

80 especially in developing countries-do so to earn higher incomes

David Satterthwaite et al., "Urbanization and Its Implications for Food and Farming," Philosophical Transactions of the Royal Society B 365, no. 1554 (2010): 280920.

81 and into the middle cla.s.s-particularly in Asia

European Strategy and Policy a.n.a.lysis System, Global Trends 2030-Citizens in an Interconnected and Polycentric World, http://www.iss.europa.eu/uploads/media/ESPAS_report_01.pdf.

82 growing global middle cla.s.s will live in cities

Ibid., p. 19.

83 more than 80 percent of global production takes place in cities

Richard Dobbs, Jaana Remes, and Charles Roxburgh, "Boomtown 2025: A Special Report," Foreign Policy, March 24, 2011.

84 significantly higher than in rural areas

David Owen, Green Metropolis: Why Living Smaller, Living Closer, and Driving Less Are the Keys to Sustainability (New York: Riverhead Trade, 2010); Qi Jingmei, "Urbanization Helps Consumption," China Daily, December 15, 2009.

85 per capita consumption of meat

United Nations Food and Agriculture Organization, "Livestock in the Balance," The State of Food and Agriculture 2009.

86 nine kilograms of plant protein are consumed

"Mankind Benefits from Eating Less Meat," PhysOrg, April 6, 2006, http://phys.org/news63547941.html.

87 even as more than 900 million people

United Nations, Millennium Development Goals Report 2011.

88 by approximately twenty pounds in the last forty years