The More We Know | Antarctic Ice Loss "Passed The Point Of No Return @TheMoreWeKnow | Uploaded May 2014 | Updated October 2024, 4 hours ago.
Six glaciers, eaten away from below by a warming of sea waters around the frozen continent, are flowing fast into the Amundsen Sea, according to the report based partly on satellite radar measurements from 1992 to 2011.
Evidence shows "a large sector of the West Antarctic ice sheet has gone into a state of irreversible retreat", said lead author Eric Rignot of the University of California, Irvine, and NASA's Jet Propulsion Laboratory in Pasadena, California.
The coastal ends of the glaciers rest on bedrock below sea level, holding back a vast weight of ice and making them vulnerable to melt, he said. He likened the process to uncorking a full bottle of wine while it was lying on its side. This part of Antarctica would be a major contributor to sea level rise in coming decades and centuries since the glaciers hold enough ice to raise sea levels by 1.2 meters (4 feet).
"We passed the point of no return in this sector and, at this point, it's just a matter of time before these glaciers completely disappear to sea," said Rignot.
Ice-penetrating radar shows no mountain ranges beneath the ice, that could possibly act as a barrier to halt the flow. The fastest retreat was 34-37 km (21-23 miles) over the period in the Smith/Kohler glacier.
The study says three major lines of evidence point to the glaciers' eventual demise: their flow speeds and how they change with time, how much each glacier is floating on seawater rather than lying on land, and the slope of the terrain they are flowing over and its depth below sea level. These glaciers already contribute significantly to sea level rise, releasing as much ice into the ocean each year as the entire Greenland Ice Sheet does.
The study focused on a sector of western Antarctica draining into the Amundsen Sea, from six principle glaciers. The biggest of the six are Pine Island glacier and Thwaites glacier.
Animation produced by NASA shows color-coded regions indicating the speed of water flowing from the glaciers into the sea. Red shows fast flow, blue a slower rate and green the slowest. Glacial water flows into the sea to form ice shelves. The areas marked in red indicate areas where Rignot says, the flow is increasing every year. Data indicates that the smaller Smith glacier has been experiencing the most dramatic changes. Between 1996 and 2011, data indicates the grounding line, where the ice edge meets the ground beneath, retreated 35 km (22 miles) at a rate of 2 km per year. Rignot says the ice melt will follow the direction of the valleys beneath the ice. There is no mountain range to slow or halt the flow.
The scientists say that a build-up of man-made greenhouse gases in the atmosphere is affecting wind patterns around Antarctica, driving warmer waters towards the continent.
However, Rignot says cuts in greenhouse gas emissions, part of efforts to rein in global warming, could at least slow the slide of the Pine Island, Thwaites, Haynes, Pope, Smith and Kohler glaciers.
Data collected from satellites and by instruments aboard NASA aircraft used in surveys of the ice sheets contributed to the study. The yearly surveys, under the auspices of NASA's Operation Ice Bridge, put multiple scientific instruments over key regions of the ice sheet to measure glacier thinning, the shape of the bed and other factors. Meanwhile, a Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Aqua satellite produced digital images of the ice sheets on a daily basis.
A separate study of the Thwaites glacier by the University of Washington in the journal Science also said it may have begun an unstoppable collapse that could last from 200 to 1,000 years.
A disappearance of the Thwaites alone would raise world sea levels by 60 cm (1.96 feet) but the "glacier also acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause another three to four meters of sea level rise", it said.
theshortpenguin.com
Six glaciers, eaten away from below by a warming of sea waters around the frozen continent, are flowing fast into the Amundsen Sea, according to the report based partly on satellite radar measurements from 1992 to 2011.
Evidence shows "a large sector of the West Antarctic ice sheet has gone into a state of irreversible retreat", said lead author Eric Rignot of the University of California, Irvine, and NASA's Jet Propulsion Laboratory in Pasadena, California.
The coastal ends of the glaciers rest on bedrock below sea level, holding back a vast weight of ice and making them vulnerable to melt, he said. He likened the process to uncorking a full bottle of wine while it was lying on its side. This part of Antarctica would be a major contributor to sea level rise in coming decades and centuries since the glaciers hold enough ice to raise sea levels by 1.2 meters (4 feet).
"We passed the point of no return in this sector and, at this point, it's just a matter of time before these glaciers completely disappear to sea," said Rignot.
Ice-penetrating radar shows no mountain ranges beneath the ice, that could possibly act as a barrier to halt the flow. The fastest retreat was 34-37 km (21-23 miles) over the period in the Smith/Kohler glacier.
The study says three major lines of evidence point to the glaciers' eventual demise: their flow speeds and how they change with time, how much each glacier is floating on seawater rather than lying on land, and the slope of the terrain they are flowing over and its depth below sea level. These glaciers already contribute significantly to sea level rise, releasing as much ice into the ocean each year as the entire Greenland Ice Sheet does.
The study focused on a sector of western Antarctica draining into the Amundsen Sea, from six principle glaciers. The biggest of the six are Pine Island glacier and Thwaites glacier.
Animation produced by NASA shows color-coded regions indicating the speed of water flowing from the glaciers into the sea. Red shows fast flow, blue a slower rate and green the slowest. Glacial water flows into the sea to form ice shelves. The areas marked in red indicate areas where Rignot says, the flow is increasing every year. Data indicates that the smaller Smith glacier has been experiencing the most dramatic changes. Between 1996 and 2011, data indicates the grounding line, where the ice edge meets the ground beneath, retreated 35 km (22 miles) at a rate of 2 km per year. Rignot says the ice melt will follow the direction of the valleys beneath the ice. There is no mountain range to slow or halt the flow.
The scientists say that a build-up of man-made greenhouse gases in the atmosphere is affecting wind patterns around Antarctica, driving warmer waters towards the continent.
However, Rignot says cuts in greenhouse gas emissions, part of efforts to rein in global warming, could at least slow the slide of the Pine Island, Thwaites, Haynes, Pope, Smith and Kohler glaciers.
Data collected from satellites and by instruments aboard NASA aircraft used in surveys of the ice sheets contributed to the study. The yearly surveys, under the auspices of NASA's Operation Ice Bridge, put multiple scientific instruments over key regions of the ice sheet to measure glacier thinning, the shape of the bed and other factors. Meanwhile, a Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA's Aqua satellite produced digital images of the ice sheets on a daily basis.
A separate study of the Thwaites glacier by the University of Washington in the journal Science also said it may have begun an unstoppable collapse that could last from 200 to 1,000 years.
A disappearance of the Thwaites alone would raise world sea levels by 60 cm (1.96 feet) but the "glacier also acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause another three to four meters of sea level rise", it said.
theshortpenguin.com
