The Nature Geoscience study doesn't answer the question of why Greenland's ice sheet successfully weathered the temperature increase that melted the North American Ice Age glaciers, note Mark Siddall of the United Kingdom's University of Bristol and Michael Kaplan of Lamont Doherty Observatory in Palisades, N.Y., in a commentary accompanying the study. But combined with "rapid ongoing changes in Greenland," the study suggests, "that we are entering into a temperature range at which the ice sheet is particularly vulnerable," they write.
So that's science for you, always advancing one study (or book) at a time, with these latest papers pointing to an added 6 to 24 inch rise in sea-level from glacial calving over the next century. King Canute's method would be much faster: Just point and command the tides. Of course, it didn't work, but that's why we dumped monarchy for science, I suppose.
Rounding out the climate news, a Proceedings of the National Academies of Science report led by Penn State's Michael Mann found this week, confirming earlier work, that the 20th Century enjoyed unusual warmth compared to at least the last 13 centuries. The finding results from a National Research Council panel recommendation two years ago that Mann and colleagues extend their "hockey stick" findings of temperatures in past centuries with more data. The hockey stick is a term coined for the chart of temperature changes that shows a sharp rise after a flat period. The results largely match the old hockey stick, just lengthening its handle.
Mann and his colleague Lee Kump have written a terrific illustrated guide to global warming, Dire Predictions: Understanding Global Warming ($25, DK Publishing), out last month, with graphics that make even the most complex climate questions easily understandable. Our graphics department will be plundering the book for the next few years.