Thursday, May 20, 2010

Ice melts, Greenland pops up

I wonder if you can hear it groan—Ice is heavy and one of the results of massive glaciers is that the sheer weight of the ice suppresses the land. Melt the ice and the land springs up. That is happening so fast in Greenland, Iceland and northern Norway that scientists from the University of Miami say they can actually see the land rise.

Every one knows it was happening. You can see it in some of the valleys of Alaska. Measuring the rise, however, is hard to do,. Seasonal changes, for instance, screw up the numbers. Additionally, whole sections of North America are still rebounding from the last ice age. The Miami researchers are using high precision satellite imaging from the GPS satellites, to measure the changes in the height of the landmass under northern glaciers. What makes the study, published in Nature Geoscience, unique is that they are measuring the rate of change. That rate has increased dramatically in the last 10 years, almost instantaneously in the way geologists measure time.

It’s true all over the North Atlantic region, wrote Yan Jiang and the team. In some cases the land is going up nearly an inch a year and by 2025 it could be twice as fast. Timothy Dixon, co-author, said: “What's surprising, and a bit worrisome, is that the ice is melting so fast that we can actually see the land uplift in response."