By IANS,
Washington : A new Colorado University study has pegged rise in sea levels to six feet by 2100, rather than the 20 feet feared by some scientists.
Tad Pfeffer, fellow of Colarado University-Boulder’s Institute of Arctic and Alpine Research and his colleagues made calculations using conservative, medium and extreme glaciological assumptions for sea rise expected from Greenland, Antarctica and smaller glaciers – the three primary contributors to sea rise.
The team concluded the most plausible scenario, when factoring in thermal expansion due to warming waters, will lead to a total sea level rise of roughly three to to six feet by 2100.
“We consider glaciological conditions required for large sea level rise to occur by 2100 and conclude increases of two metres are physically untenable,” the team wrote.
“We find that a total sea level rise of about two metres by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits.”
“The gist of the study is that very simple, physical considerations show that some of the very large predictions of sea level rise are unlikely, because there is simply no way to move the ice or the water into the ocean that fast,” said Pfeffer.
The team began the study by postulating future sea level rise at about two metres by 2100 produced only by Greenland, said Pfeffer. Since rapid, unstable ice discharge into the ocean is restricted to Greenland glacier beds based below sea level, they identified and mapped all of the so-called outlet glacier “gates” on Greenland’s perimeter – bedrock bottlenecks most tightly constraining ice and water discharge.
“For Greenland alone to raise sea level by two metres by 2100, all of the outlet glaciers involved would need to move more than three times faster than the fastest outlet glaciers ever observed, or more than 70 times faster than they presently move,” said Pfeffer.
“And they would have to start moving that fast today, not 10 years from now. It is a simple argument with no fancy physics.”
The team also used assessments of the world’s small glacier and ice cap contributions to sea level rise calculated by a CU-Boulder team and published in July 2007.
The report was published in the Friday issue of Science.