Antarctica’s exit glaciers: The drunk drivers of climate change

Penn State's Richard Alley is prone to both colorful metaphors and colorful teaching techniques.

Penn State

Richard Alley's studies of the role of ice sheets in climate change have earned him various awards, a PBS special, and have made him a repeat performer at the meetings of the American Association for the Advancement of Science. When I first saw him speak a few years ago, he argued that the ice sheets of Antarctica and Greenland play a huge role in controlling sea levels. Mountain glaciers don't hold nearly as much water, while the thermal expansion of water in the oceans is a slower and more predictable process.

The ice sheets, in contrast, have been a big unknown. At the time, we didn't yet fully understand how much of them might melt, or how quickly they might dump water into the oceans.

Alley was back at this year's meeting, and his news was mixed. As he predicted in his earlier appearance, a few years of intensive study have helped narrow down some of the uncertainties. And, while the news is (relatively) good in Greenland, some of the results from Antarctica are decidedly worrying.