April 16, 2009
WARNING: Catastrophic Sea Levels Within 50 Years
A new study analyzing the fluctuations in sea levels during the last time Earth was between ice ages shows that oceans rose some nine feet in only decades due to collapsing ice sheets, the AFP reported.
Lead researcher Paul Blanchon, a geoscientist at Mexico's National University, said the findings suggest that such a scenario would redraw coastlines worldwide and unleash colossal human misery.Worst of all, he said it was "now a distinct possibility within the next 100 years."
Scientists see rising ocean watermarks as the most serious likely consequence of global warming.
Sea levels are predicted to rise by up to 23 inches before 2100 due simply to the expansion of warmer ocean waters, according to a UN Intergovernmental Panel on Climate Change (IPCC) report in 2007.
But such an increase would make many small island nations uninhabitable and would likely disrupt the lives of tens of millions of people living in low-lying deltas, especially in Asia and Africa.
The potential impact of crumbling ice sheets in western Antarctica and Greenland, which together contain enough frozen water to boost average global sea levels by at least 42 feet, have sounded alarms with climate scientists.
Dozens of major cities around the globe, including Shanghai, Calcutta, New Orleans, Miami and Dhaka would be devastated by a rapid 9-foot rise.
Blanchon told AFP that scientists have tended to assume that sea level reached a maximum during the last interglacial"”some 120,000 years ago"”very slowly, over several millennia.
"What we are saying is 'no, they didn't'," he said.
The researchers from the Leibniz Institute of Marine Science in Germany discovered the remains of coral reefs that made it possible to measure with great precision changes in sea level.
Blanchon and colleagues pinpointed a dramatic jump in sea levels that occurred 121,000 years ago using contiguous reef crests"”the part of the reef closest to the surface of the water"”as benchmarks.
He suggests we are looking at a nine-foot rise within 50 years.
"This is the first evidence that we have for rapid change in sea level during that time," he said, adding that only collapsing ice sheets could account for such an abrupt increase.
Experts say the last interglacial period, when sea levels peaked nearly twenty feet higher than current levels, was warmer than the world is today.
Scientists now worry that rising temperatures could create a similar environment, as manmade climate change kicks in, triggering a runaway disintegration of the continent-sized ice blocks that are already melting at an alarming rate.
While not adding itself to sea levels, the recent breakaway of the Wilkins Ice Shelf from the Antarctic Peninsula makes it easier for the glaciers that feed it to flow straight out to the ocean.
But many say it is still unclear whether this and other dramatic ice sheet changes recorded recently are signs of imminent collapse or natural processes that have not been observed before.
The study, published by the science journal Nature, will appear in print Thursday.
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