Hansen on Climate Change

In The New York Review of Books, Jim Hansen provides an in-depth overview of climate change, with reviews of Tim Flannery’s The Weather Maker’s, Elizabeth Kolbert’s Field Notes from a Catastrophe, and the Gore documentary An Inconvenient Truth, which I expect to see this weekend. Here’s one particularly alarming passage:

How much will sea level rise with five degrees of global warming? Here too, our best information comes from the Earth’s history. The last time that the Earth was five degrees warmer was three million years ago, when sea level was about eighty feet higher.

Eighty feet! In that case, the United States would lose most East Coast cities: Boston, New York, Philadelphia, Washington, and Miami; indeed, practically the entire state of Florida would be under water. Fifty million people in the US live below that sea level. Other places would fare worse. China would have 250 million displaced persons. Bangladesh would produce 120 million refugees, practically the entire nation. India would lose the land of 150 million people.

A rise in sea level, necessarily, begins slowly. Massive ice sheets must be softened and weakened before rapid disintegration and melting occurs and the sea level rises. It may require as much as a few centuries to produce most of the long-term response. But the inertia of ice sheets is not our ally against the effects of global warming. The Earth’s history reveals cases in which sea level, once ice sheets began to collapse, rose one meter (1.1 yards) every twenty years for centuries. That would be a calamity for hundreds of cities around the world, most of them far larger than New Orleans. Devastation from a rising sea occurs as the result of local storms which can be expected to cause repeated retreats from transitory shorelines and rebuilding away from them.

Hansen and Kolbert were guests on On Point the other night, and Hansen repeated a comment that Larry King had made to him recently: “Nobody cares about fifty years from now.” The point was then made that the founders of this country (to choose one) certainly cared about such a thing. I believe it was Kolbert who suggested that a nation or civilization that refuses to consider a half-century ahead of them is in real trouble.