Earth has usually been much warmer than it is today. During the high point of the Mesozoic era, in fact, the sea surface temperature may have been 31°F warmer than at present. Yet life was abundant on...

Earth has usually been much warmer than it is today. During the high point of the Mesozoic era, in fact, the sea surface temperature may have been 31°F warmer than at present. Yet life was abundant on planet Earth in the Mesozoic era. Why then do we worry about high surface temperatures today?