By James S. Russell, Island Press, 312 pages, 2011, $35 James Russell argues in this well-researched and persuasive book that cities will need to become agile: to adapt to the climate changes already in progress and to reduce the potential for a global environmental catastrophe as the world races towards a population of more than 10 billion.  Transitioning to energy-efficient buildings is one form of agility open to all cities. Adopting planning measures that preserve more of the natural environment, supported by diverse forms of transportation and not just highways, is another strategy within the control of state and local