Maybe a president or Congressional leader will, upon reading a report by the American Academy of Arts and Sciences or hearing a plea from the leader of another country or even glancing at this book, become convinced of the need to take substantial action to address the dangers of global warming. Once convinced, this leader would build broad political coalitions with other political figures based on reasoned appreciation of a real environmental problem, and devise a comprehensive set of policy reforms to reduce America's key role in promoting global warming. Within a few years, the United States would develop and implement a range of policies to reduce the concentration of CO2 in the atmosphere, including dedicated taxes, regulatory reforms, and large-scale initiatives in renewable energy and energy conservation.

This could happen, but that's not the way major changes in American history have taken place before. Reasoned discourse needs a push. Elected officials, even presidents, are subject to an ever-expanding range of pressures and constraints, making substantial policy reform in any area exceedingly difficult. Further, the American Constitution established a governmental structure built to produce stability rather than innovation, solidity rather than responsiveness – in effect, a Humvee rather than a hybrid of government. But substantial, if sometimes unwelcome, innovations in policy have taken place in America, including (among others) the institution of a federal social safety net for the elderly in the 1930s, the establishment of a permanent and globally engaged military establishment in the 1940s, federal intervention in the cause of civil rights and women's rights in the 1950s and 1960s, and a broad retrenchment in government support for the less fortunate, commenced in the 1970s.