Scientists Discover Another Reason for Glacial Acceleration
November 17, 2008
File photo of an iceberg in North Bay, Rothera Point, Adelaide Island, Antarctica. Scientists unveiled Sunday the first direct evidence that massive floods deep below Antarctica's ice cover are accelerating the flow of glaciers into the sea.
(PhysOrg.com) -- Using nearly 50 years of data, University of Maine researchers have determined that subglacial floods in East Antarctica caused a rapid and short-lived acceleration of a major outlet glacier.
Leigh Stearns and Gordon Hamilton of UMaine's Climate Change Institute, along with Benjamin Smith of the University of Washington, observed that the flow rate of a large outlet glacier in East Antarctica increased by about 10 percent in response to the flooding of two subglacial lakes.
The team's findings are based on a 48-year record of ice velocities along Byrd Glacier, East Antarctica along with recent satellite observations of ice surface elevation and ice velocities from NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer instrument on NASA's Terra satellite; the Ice, Cloud and Land Elevation Satellite; and Landsat; as well as SPOT and Japan's Advanced Land Observing Satellite, and have been reported in a Nature Geoscience paper.
"We saw that there was this very rapid acceleration of the glacier that we didn't initially have an explanation for," Hamilton said.
It wasn't until Stearns presented these observations at a conference last year that we recognized the connection between the glacier acceleration and the subglacial drainage event.
"After my presentation," explains Stearns, "Ben [Smith, co-author] and I compared the timing of the flooding event that he measured, and the acceleration of Byrd Glacier, and were excited to find that they occurred at roughly the same time."
The increase in ice flow speed coincides with rapid changes in ice surface elevation about 200 km upstream, which the research team interprets as the filling and draining of two subglacial lakes.
"Our work shows that the speed of the glacier can change by a very large amount," Hamilton said. "It only lasted for a year, but if the same process happens again at a larger scale, sea level could rise much quicker."
For the past year, some of the team's colleagues have been mapping subglacial lakes and discovered that they are quite prevalent.
"Our understanding of why they occur is minimal," Hamilton said, noting that it previously was thought that these lakes were stable and relatively inactive.
"The more we look, the more we see that these lakes fill up and drain," Hamilton said.
"One of the implications of this work," explains Stearns, "is that the addition of even a small amount of water to the bottom of a glacier can cause significant acceleration. While the changes taking place on Byrd Glacier are not caused by climate-driven processes, they highlight the sensitivity of glaciers to small changes."
Future investigations are expected to look at other subglacial lakes to measure their activity and determine how to include subglacial flooding in current ice sheet models for more accurate predictions of sea level changes.
"We need to include all the important processes that cause the ice sheets to grow and shrink," Hamilton said.
Provided by University of Maine
Nov 10, 2009 |
not rated yet |
0
.jpg)
The oceans have been rising for tens of thousands of years, and have varied by hundreds of meters over time. It is ignorant to attribute any sort of crisis to this phenomenon, and it is downright malicious to use it for political and economic gain.
Governments find themselves desperate to erect a new framework for their massive, defunct cold war bureaucracies, and the more devious within them have latched onto ecology as a means to unify their efforts and generate the new crisis needed to justify their power schemes.
Along with terrorism, eco-hysteria seems to be the engine the powers-that-be want to drive for their own profit and power.
Not a single governmental mandate can alter earth's climate, and no one can claim we even begin to understand the great number of variables or the relationships between them. It is irresponsible and dangerous for political (read: UNSCIENTIFIC) figures to make policy based on fallacious and incomplete data.
Don't suppose you have a reference for that little error? No, of course not.
The Ice Age was thousands of years ago. Had to be pretty cold for that I'd say.