�If the lessons being learned by scientists more or less the dying of the last great North American ice piece of paper are rectify, estimates of global sea level heighten from a melting Greenland ice sheet may be seriously underestimated.
Writing in the journal Nature Geoscience, a team of researchers lED by University of Wisconsin-Madison geologist Anders Carlson reports that sea level rise from greenhouse-induced warming of the Greenland ice weather sheet could be double or triple stream estimates over the side by side century.
"We're non talking around something catastrophic, but we could examine a practically bigger reception in footing of ocean level from the Greenland ice sheet over the next century years than what is currently predicted," says Carlson, a UW-Madison professor of geology and geophysics. Carlson worked with an outside team of researchers, including Allegra LeGrande from the NASA Center for Climate Systems at Columbia University, and colleagues at the Woods Hole Oceanographic Institution, the California Institute of Technology, University of British Columbia and University of New Hampshire.
Scientists have yet to agree on how much melting of the Greenland ice sheet - a terrestrial ice mass encompassing 1.7 trillion square kilometers - will contribute to changes in sea level. One cause, Carlson explains, is that in recorded history there is no precedent for the influence of climate change on a massive ice sheet.
"We've never seen an internal-combustion engine sheet go away before, just here we have a record," says Carlson of the new study that combined a powerful information processing system model with marine and terrestrial records to provide a shot of how fast ice sheets can buoy melt and raise sea level in a heater world.
Carlson and his group were able-bodied to get on the lessons of the disappearance of the Laurentide ice sheet, the last gravid ice mass to underwrite much of the northern hemisphere. The Laurentide methedrine sheet, which encompassed large parts of what ar now Canada and the United States, began to melt some 10,000 years agone in reply to increased solar radiation in the northern cerebral hemisphere due to a cyclic change in the orientation of the Earth's axis. It experient two speedy pulses of melting - one 9,000 age ago and another 7,600 age ago - that caused global sea level to rise by more than half an inch per year.
Those pulses of melt, according to the new study, occurred when summer air temperatures were similar to what are predicted for Greenland by the end of this hundred, a finding the suggests estimates of global sea level uprise due to a warming world mood may be seriously underestimated.
The most recent estimates of sea level rise due to melt of the Greenland water ice sheet by the Intergovernmental Panel on Climate Change (IPCC) suggest a maximum sea layer rise during the adjacent 100 old age of nearly 1 to 4 inches. That estimate, Carlson and his colleagues note, is based on limited data, mostly from the last decade, and contrasts sharply with results from computing machine models of future clime, casting dubiety on stream estimates of change in sea layer due to melting ice sheets.
According to the raw study, rising sea levels up to a one-third of an inch per year or 1 to 2 feet over the course of a century are possible.
Even slight rises in worldwide sea level are problematic as a significant share of the world's human population - hundreds of millions of people - lives in areas that can be affected by rising seas.
"For planning purposes, we should see the IPCC projections as cautious," Carlson says. "We suppose this is a very low estimate of what the Greenland ice sheet will kick in to sea level."
The authors of the new Nature Geoscience report were able to document the retreat of the Laurentide ice rink sheet and its contributions to changes in sea level by measuring how long rocks once covered by frappe have been exposed to cosmic radiation, estimates of ice retreat based on radiocarbon dates from organic material as well as changes in ocean salinity.
In addition to Carlson and LeGrande, co-authors of the study, which was funded primarily by the National Science Foundation, are Gavin A. Schmidt of Columbia University, Delia W. Oppo of the Woods Hole Oceanographic Institution, Rosemarie E. Came of the California Institute of Technology, Faron S. Anslow of the University of British Columbia, Joseph M. Licciardi of the University of New Hampshire and Elizabeth A. Obbink of UW-Madison.
Terry Devitt
Source: Anders Carlson
University of Wisconsin-Madison
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