Monday, May 12, 2014

Kiss it Goodbye

The West Antarctic Ice Sheet, that is. Also New York City, Miami, and much of Bangla Desh and most of the world's other low lying cities. According to this NYT Article by Justin Gillis and Kenneth Chang, the disintegration of that ice sheet has begun, and will probably continue over the next few centuries, apparently more or less independently of anything we do about climate change. The good news is that it probably won't be very fast for next 100 years or so - so don't sell that beachfront property quite yet.

The precise causes are unknown, though AGW and the Ozone hole are suspects.

Most scientists in the field see a connection between the stronger winds and human-caused global warming, but they say other factors are likely at work, too. Natural variability of climate may be one of them. Another may be the ozone hole over Antarctica, caused by an entirely different environmental problem, the human release of ozone-destroying gases.

Whatever the mix of causes, they appear to have triggered a retreat of the ice sheet that can no longer be stopped, even if the factors drawing in the warmer water were to reverse suddenly, the scientists said. At this point, a decrease in the melt rate back to earlier levels would be “too little, too late to stabilize the ice sheet,” said Ian Joughin, a glaciologist at the University of Washington and lead author of the new paper in Science. “There’s no stabilization mechanism.”

The basic problem is that much of the West Antarctic ice sheet sits below sea level in a kind of bowl-shaped depression the earth. As Dr. Mercer outlined in 1978, once the part of the ice sheet sitting on the rim of the bowl melts and the ice retreats into deeper water, it becomes unstable and highly vulnerable to further melting.