Geoengineering May Be Our Best Chance to Save Sea Ice

I first went to the Arctic in the summer of 1970, aboard the Canadian oceanographic ship Hudson , which was carrying out the first circumnavigation of the Americas. The ship was ice-strengthened and needed to be. Along the coasts of Alaska and the Northwest Territories, Arctic Ocean ice lay close in to land, leaving a gap of only a few miles to do our survey. Sometimes ice went right up to the coast. That was considered normal.

Today a ship entering the Arctic from the Bering Strait in summer finds an ocean of open water in front of her. Water extends far to the north, stopping only a few miles short of the pole. From space the top of the world now looks blue instead of white. Things are worse than appearances would suggest, however. What ice is still left is thin--average thickness dropped 43 percent between 1976 and 1999, sonar measurements show. By 2015, at this rate, summer melting will outstrip the accumulation of new ice in winter, and the entire ice cover will collapse. Once summer ice goes away entirely, the physics of latent heat will make it very difficult, if not impossible, to get it back. We will have entered what Mark C. Serreze, director of the National Snow and Ice Data Center at the University of Colorado at Boulder, calls the Arctic “death spiral.”