Glaciers seen during NASA’s Operation IceBridge research flight to West Antarctica on Oct. 29, 2014. Photo: NASA/Michael Studinger
Glaciers in one part of West Antarctica are melting at triple the rate of a decade ago and have become the most significant contributor to sea level rise in that region, a new study says.
The study found that the glaciers in the Amundsen Sea Embayment of West Antarctica have shrunk by an average of 83 gigatons a year for two decades—the equivalent of the weight of Mount Everest every two years. And the loss rate is accelerating: The scientists estimate ice loss at 102 gigatons per year for 2003-2011.
Filed under Climate, Science
The leading edge of the floating ice tongue of the Pine Island Glacier, Antarctica. Photo: M. Wolovick
(First posted May 23, 2014 on State of the Planet.)
Reports that a portion of the West Antarctic Ice Sheet has begun to irretrievably collapse, threatening a 4-foot rise in sea levels over the next couple of centuries, surged through the news media last week. But many are asking if even this dramatic news will alter the policy conversation over what to do about climate change.
Glaciers like the ones that were the focus of two new studies move at, well, a glacial pace. Researchers are used to contemplating changes that happen over many thousands of years.
This time, however, we’re talking hundreds of years, perhaps — something that can be understood in comparison to recent history, a timescale of several human generations. In that time, the papers’ authors suggest, melting ice could raise sea levels enough to inundate or at least threaten the shorelines where tens of millions of people live.
“The high-resolution records that we’re getting and the high-resolution models we’re able to make now are sort of moving the questions a little bit closer into human, understandable time frames,” said Kirsty Tinto, a researcher from Lamont-Doherty Earth Observatory who has spent a decade studying the Antarctic.
“We’re still not saying things are going to happen this year or next year. But it’s easier to grasp [a couple of hundred years] than the time scales we’re used to looking at.”
First posted Feb. 9, 2012 on the Earth Institute’s State of the Planet blog.
A satellite photo of Antarctica showing (red oval) the location of Lake Vostok. Photo: NASA-GISS
Russian scientists this week finished penetrating more than two miles through the Antarctic ice sheet to Lake Vostok, a huge freshwater lake that has been buried under the ice for millions of years. The feat has taken two decades to accomplish, but the scientists won’t know what they’ve found until next year — the team quickly exited the research station, located in the middle of the continent 800 miles from the South Pole, to avoid increasingly harsh polar conditions.
When the drilling reached the lake, 3,769 meters (12,366 feet) down, water, under great pressure from the ice above it, shot up the bore hole and froze. The Russians say this kept the chemicals used in the drilling process from entering the lake. They will return during the next Antarctic summer to retrieve the sample of frozen lake water.
“It would be the first sampling of a subglacial lake, of the biggest subglacial lake,” said Robin E. Bell, a research professor at Lamont-Doherty Earth Observatory whose work has helped map Vostok and other such lakes under the Antarctic ice. Bell said Vostok was “discovered” by a pilot flying over the area who noticed a distinct flat region on the ice surface – marking the vast lake far below. Bell and colleagues undertook the first systematic survey to determine how much water was in the lake more than a decade ago. Continue reading
First published March 2, 2011, on the Lamont-Doherty Earth Observatory web site, http://www.ldeo.columbia.edu.
The radar image shows the Gamburtsev Mountains, at bottom of the image, overlain by the ice sheet, which has been deformed by a bulge of refrozen ice (center). (Courtesy Bell et al., 2011)
Scientists working in the remotest part of Antarctica have discovered that liquid water locked deep under the continent’s coat of ice regularly thaws and refreezes to the bottom, creating as much as half the thickness of the ice in places, and actively modifying its structure. The finding, which turns common perceptions of glacial formation upside down, could reshape scientists’ understanding of how the ice sheet expands and moves, and how it might react to warming climate, they say. The study appears in this week’s early online edition of the leading journal Science; it is part of a six-nation study of the invisible Gamburtsev Mountains, which lie buried under as much as two miles of ice.
Ice sheets are well known to grow from the top as snow falls and builds up annual layers over thousands of years, but scientists until recently have known little about the processes going on far below. In 2006, researchers in the current study showed that lakes of liquid water underlie widespread parts of Antarctica. In 2008-2009, they mounted an expedition using geophysical instruments to create 3-D images of the Gamburtsevs
, a range larger than the European Alps. The expedition also made detailed images of the overlying ice, and subglacial water.