What We Know About Climate Change

The vast majority of scientists agree that human activity has significantly increased
greenhouse gases in the atmosphere--most dramatically since the 1970s. In February 2007 the
Intergovernmental Panel on Climate Change found that global warming is "unequivocal" and
that human-produced carbon dioxide and other greenhouse gases are chiefly to blame, to a certainty
of more than 90 percent. Yet global warming skeptics and ill-informed elected officials continue to
dismiss this broad scientific consensus. In What We Know About Climate Change, MIT atmospheric
scientist Kerry Emanuel outlines the basic science of global warming and how the current consensus
has emerged. Although it is impossible to predict exactly when the most dramatic effects of global
warming will be felt, he argues, we can be confident that we face real dangers. Emanuel, whose work
was widely cited in media coverage of Hurricane Katrina, warns that global warming will contribute
to an increase in the intensity and power of hurricanes and flooding and more rapidly advancing
deserts. But just as our actions have created the looming crisis, so too might they avert it.
Emanuel calls for urgent action to reduce greenhouse gases and criticizes the media for playing down
the dangers of global warming (and, in search of "balance," quoting extremists who deny
its existence). An afterword by environmental policy experts Judith Layzer and William Moomaw
discusses how the United States could lead the way in the policy changes required to deal with
global warming. Kerry Emanuel is Professor of Atmospheric Science in the Department of Earth,
Atmospheric, and Planetary Science at MIT. He is the author of Divine Wind: The History and Science
of Hurricanes and Atmospheric Convection. In May 2006 he was named one of Time magazine's "Time
100: The People Who Shape Our World."