The eastern United States must plan on the very real possibility that total sea level rise by 2100 will exceed 6 feet on our current emissions path. Sadly, the Washington Post got the only story half right.
This week I’ll focus on our best understanding of the impacts that Americans face from human-caused climate change. On Tuesday, the US Global Change Research Program is releasing its long-awaited comprehensive analysis of Global Climate Change Impacts in United States. We’ll see how it matches up against my not-so-well-funded analysis, “Yes, the science says on our current emissions path we are projected to warm most of U.S. 10 – 15°F by 2100, with sea level rise of 5 feet or more, and the SW will be a permanent Dust Bowl.”
First, though, let’s do a comprehensive review of projected sea level rise (SLR), starting with two recent studies on what accelerated melting of the Greenland ice sheet might mean for us. The University of Alaska Fairbanks reports on a brand new study in the journal Hydrological Processes (subs. req’d):
The Greenland ice sheet is melting faster than expected according to a new study….
Study results indicate that the ice sheet may be responsible for nearly 25 percent of global sea rise in the past 13 years. The study also shows that seas now are rising by more than 3 millimeters a year–more than 50 percent faster than the average for the 20th century.
UAF researcher Sebastian H. Mernild and colleagues from the United States, United Kingdom and Denmark discovered that from 1995 to 2007, overall precipitation on the ice sheet decreased while surface ablation–the combination of evaporation, melting and calving of the ice sheet–increased. According to Mernild’s new data, since 1995 the ice sheet lost an average of 265 cubic kilometers per year, which has contributed to about 0.7 millimeters per year in global sea level rise.
This research is consistent with data presented at the annual meeting of the American Geophysical Union in December (see “Two trillion tons of land ice lost since 2003, rate of Greenland summer ice loss triples 2007 record“). This staggering ice loss is all the more worrisome because it was not predicted by the IPCC’s climate models. As Penn State climatologist Richard Alley said in March 2006, the ice sheets appear to be shrinking “100 years ahead of schedule.” In 2001, the IPCC thought that neither Greenland nor Antarctica would lose significant mass by 2100. They both already are.
And, of course, Greenland is facing an almost incomprehensible amount of warming if we stay anywhere near our current emissions path — see “M.I.T. doubles its 2095 warming projection to 10°F “” with 866 ppm and Arctic warming of 20°F.”
Especially worrisome for North America is that a new study in Geophysical Research Letters (subs. req’d) finds that sustained high rates of Greenland ice loss could lead to staggering increases in coastal sea level rise. As reported: