Sunday, November 06, 2011 12:25:29 AM
F6 .. Ocean Currents Speed Melting of Antarctic Ice: A Major Glacier Is Undermined from Below
Scientists aboard the Nathaniel B. Palmer visited the
Amundsen Sea region in 2009 to study oceanic changes.
(Credit: Frank Nitsche, Lamont-Doherty Earth Observatory)
ScienceDaily (June 26, 2011) — Stronger ocean currents beneath West Antarctica's Pine Island Glacier Ice Shelf are eroding the ice from below, speeding the melting of the glacier as a whole, according to a new study in Nature Geoscience. A growing cavity beneath the ice shelf has allowed more warm water to melt the ice, the researchers say -- a process that feeds back into the ongoing rise in global sea levels. The glacier is currently sliding into the sea at a clip of four kilometers (2.5 miles) a year, while its ice shelf is melting at about 80 cubic kilometers a year -- 50 percent faster than it was in the early 1990s -- the paper estimates.
...............
See Also: [links inside] .. Earth & Climate .. Global Warming .. Oceanography .. Climate .. Snow and Avalanches .. Ice Ages .. Water
Reference .. Ice shelf .. Antarctic ice sheet .. Ice sheet .. Larsen Ice Shelf ..
...............
"More warm water from the deep ocean is entering the cavity beneath the ice shelf, and it is warmest where the ice is thickest," said study's lead author, Stan Jacobs, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory.
In 2009, Jacobs and an international team of scientists sailed to the Amundsen Sea aboard the icebreaking ship Nathaniel B. Palmer to study the region's thinning ice shelves -- floating tongues of ice where landbound glaciers meet the sea. One goal was to study oceanic changes near the Pine Island Glacier Ice Shelf, which they had visited in an earlier expedition, in 1994. The researchers found that in 15 years, melting beneath the ice shelf had risen by about 50 percent. Although regional ocean temperatures had also warmed slightly, by 0.2 degrees C or so, that was not enough to account for the jump.
The local geology offered one explanation. On the same cruise, a group led by Adrian Jenkins, a researcher at British Antarctic Survey and study co-author, sent a robot submarine beneath the ice shelf, revealing an underwater ridge. The researchers surmised that the ridge had once slowed the glacier like a giant retaining wall. When the receding glacier detached from the ridge, sometime before the 1970s, the warm deep water gained access to deeper parts of the glacier. Over time, the inner cavity grew, more warm deep water flowed in, more melt water flowed out, and the ice thinned. With less friction between the ice shelf and seafloor, the landbound glacier behind it accelerated its slide into the sea. Other glaciers in the Amundsen region have also thinned or widened, including Thwaites Glacier and the much larger Getz Ice Shelf.
One day, near the southern edge of Pine Island Glacier Ice Shelf, the researchers directly observed the strength of the melting process as they watched frigid, seawater appear to boil on the surface like a kettle on the stove. To Jacobs, it suggested that deep water, buoyed by added fresh glacial melt, was rising to the surface in a process called upwelling. Jacobs had never witnessed upwelling first hand, but colleagues had described something similar in the fjords of Greenland, where summer runoff and melting glacier fronts can also drive buoyant plumes to the sea surface.
In recent decades, researchers have found evidence that Antarctica is getting windier, and this may also help explain the changes in ocean circulation. Stronger circumpolar winds would tend to push sea ice and surface water north, says Jacobs. That in turn, would allow more warm water from the deep ocean to upwell onto the Amundsen Sea's continental shelf and into its ice shelf cavities.
Pine Island Glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide. Global sea levels are currently rising at about 3 millimeters (.12 inches) a year. By one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 centimeters (9 inches).
The paper adds important and timely insights about oceanic changes in the region, says Eric Rignot, a professor at University of California at Irvine and a senior research scientist at NASA's Jet Propulsion Laboratory. "The main reason the glaciers are thinning in this region, we think, is the presence of warm waters," he said. "Warm waters did not get there because the ocean warmed up, but because of subtle changes in ocean circulation. Ocean circulation is key. This study reinforces this concept."
The study received funding from the US National Science Foundation and the UK National Environment Research Council.
http://www.sciencedaily.com/releases/2011/06/110626145308.htm
=================
Snowball Effect Fuels Arctic Meltdown
Sara Goudarzi
Date: 04 October 2006 Time: 08:46 AM ET
A floating iceberg off the Antarctic Peninsula. Photo courtesy CU-Boulder National
Snow and Ice Data Center
A pair of studies out this week along with other recent evidence suggests an observed meltdown of Arctic ice is snowballing into a situation that could leave the North Pole ice-free during summer in just a few decades.
A rapid annual retreat of ice is exposing the darker ocean, which absorbs more of the sun's energy and fuels increased melting of ice.
"I'm not terribly optimistic about the future of the ice," said Mark Serreze, a research professor at the University of Colorado at Boulder’s National Snow and Ice Data Center (NSIDC). "As greenhouse gases continue to rise, the Arctic will continue to lose its ice. You just can't argue with the physics."
.. so many links inside! .. e.g. ..
The Possibilities .. More Rain but Less Water .. Ice-Free Arctic Summers .. Overwhelmed Storm Drains .. Worst Mass Extinction Ever .. A Chilled Planet
Strange Solutions .. Inject Sulfur into Air to Battle Global Warming .. Space Ring to Shade Earth .. Longer Airline Flights
[...]
Snowball effect
Higher-than-normal winter temperatures of the Artic in the past couple of years led to limited ice growth. And most of the ice that formed was thinner than normal. So when temperatures are higher than normal in summer, the ice melts faster than it would have were it thicker.
A snowball effect is in place.
"Melting ice means more of the dark ocean is exposed, allowing it to absorb more of the sun's energy, further increasing air temperatures, ocean temperatures, and ice melt," said Ted Scambos, a scientist from CU-Boulder. "It seems that this feedback, which is a major reason for the pronounced effects of greenhouse warming in the Arctic, is really starting to kick in."
http://www.livescience.com/1058-snowball-effect-fuels-arctic-meltdown.html
What an amazing place! .. your photo ..
In October, 2011, NASA's Operation IceBridge discovered a major rift in the Pine
Island Glacier in western Antarctica. Credit: NASA
It would be a calamity to lose the ice.
Scientists aboard the Nathaniel B. Palmer visited the
Amundsen Sea region in 2009 to study oceanic changes.
(Credit: Frank Nitsche, Lamont-Doherty Earth Observatory)
ScienceDaily (June 26, 2011) — Stronger ocean currents beneath West Antarctica's Pine Island Glacier Ice Shelf are eroding the ice from below, speeding the melting of the glacier as a whole, according to a new study in Nature Geoscience. A growing cavity beneath the ice shelf has allowed more warm water to melt the ice, the researchers say -- a process that feeds back into the ongoing rise in global sea levels. The glacier is currently sliding into the sea at a clip of four kilometers (2.5 miles) a year, while its ice shelf is melting at about 80 cubic kilometers a year -- 50 percent faster than it was in the early 1990s -- the paper estimates.
...............
See Also: [links inside] .. Earth & Climate .. Global Warming .. Oceanography .. Climate .. Snow and Avalanches .. Ice Ages .. Water
Reference .. Ice shelf .. Antarctic ice sheet .. Ice sheet .. Larsen Ice Shelf ..
...............
"More warm water from the deep ocean is entering the cavity beneath the ice shelf, and it is warmest where the ice is thickest," said study's lead author, Stan Jacobs, an oceanographer at Columbia University's Lamont-Doherty Earth Observatory.
In 2009, Jacobs and an international team of scientists sailed to the Amundsen Sea aboard the icebreaking ship Nathaniel B. Palmer to study the region's thinning ice shelves -- floating tongues of ice where landbound glaciers meet the sea. One goal was to study oceanic changes near the Pine Island Glacier Ice Shelf, which they had visited in an earlier expedition, in 1994. The researchers found that in 15 years, melting beneath the ice shelf had risen by about 50 percent. Although regional ocean temperatures had also warmed slightly, by 0.2 degrees C or so, that was not enough to account for the jump.
The local geology offered one explanation. On the same cruise, a group led by Adrian Jenkins, a researcher at British Antarctic Survey and study co-author, sent a robot submarine beneath the ice shelf, revealing an underwater ridge. The researchers surmised that the ridge had once slowed the glacier like a giant retaining wall. When the receding glacier detached from the ridge, sometime before the 1970s, the warm deep water gained access to deeper parts of the glacier. Over time, the inner cavity grew, more warm deep water flowed in, more melt water flowed out, and the ice thinned. With less friction between the ice shelf and seafloor, the landbound glacier behind it accelerated its slide into the sea. Other glaciers in the Amundsen region have also thinned or widened, including Thwaites Glacier and the much larger Getz Ice Shelf.
One day, near the southern edge of Pine Island Glacier Ice Shelf, the researchers directly observed the strength of the melting process as they watched frigid, seawater appear to boil on the surface like a kettle on the stove. To Jacobs, it suggested that deep water, buoyed by added fresh glacial melt, was rising to the surface in a process called upwelling. Jacobs had never witnessed upwelling first hand, but colleagues had described something similar in the fjords of Greenland, where summer runoff and melting glacier fronts can also drive buoyant plumes to the sea surface.
In recent decades, researchers have found evidence that Antarctica is getting windier, and this may also help explain the changes in ocean circulation. Stronger circumpolar winds would tend to push sea ice and surface water north, says Jacobs. That in turn, would allow more warm water from the deep ocean to upwell onto the Amundsen Sea's continental shelf and into its ice shelf cavities.
Pine Island Glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide. Global sea levels are currently rising at about 3 millimeters (.12 inches) a year. By one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 centimeters (9 inches).
The paper adds important and timely insights about oceanic changes in the region, says Eric Rignot, a professor at University of California at Irvine and a senior research scientist at NASA's Jet Propulsion Laboratory. "The main reason the glaciers are thinning in this region, we think, is the presence of warm waters," he said. "Warm waters did not get there because the ocean warmed up, but because of subtle changes in ocean circulation. Ocean circulation is key. This study reinforces this concept."
The study received funding from the US National Science Foundation and the UK National Environment Research Council.
http://www.sciencedaily.com/releases/2011/06/110626145308.htm
=================
Snowball Effect Fuels Arctic Meltdown
Sara Goudarzi
Date: 04 October 2006 Time: 08:46 AM ET
A floating iceberg off the Antarctic Peninsula. Photo courtesy CU-Boulder National
Snow and Ice Data Center
A pair of studies out this week along with other recent evidence suggests an observed meltdown of Arctic ice is snowballing into a situation that could leave the North Pole ice-free during summer in just a few decades.
A rapid annual retreat of ice is exposing the darker ocean, which absorbs more of the sun's energy and fuels increased melting of ice.
"I'm not terribly optimistic about the future of the ice," said Mark Serreze, a research professor at the University of Colorado at Boulder’s National Snow and Ice Data Center (NSIDC). "As greenhouse gases continue to rise, the Arctic will continue to lose its ice. You just can't argue with the physics."
.. so many links inside! .. e.g. ..
The Possibilities .. More Rain but Less Water .. Ice-Free Arctic Summers .. Overwhelmed Storm Drains .. Worst Mass Extinction Ever .. A Chilled Planet
Strange Solutions .. Inject Sulfur into Air to Battle Global Warming .. Space Ring to Shade Earth .. Longer Airline Flights
[...]
Snowball effect
Higher-than-normal winter temperatures of the Artic in the past couple of years led to limited ice growth. And most of the ice that formed was thinner than normal. So when temperatures are higher than normal in summer, the ice melts faster than it would have were it thicker.
A snowball effect is in place.
"Melting ice means more of the dark ocean is exposed, allowing it to absorb more of the sun's energy, further increasing air temperatures, ocean temperatures, and ice melt," said Ted Scambos, a scientist from CU-Boulder. "It seems that this feedback, which is a major reason for the pronounced effects of greenhouse warming in the Arctic, is really starting to kick in."
http://www.livescience.com/1058-snowball-effect-fuels-arctic-meltdown.html
What an amazing place! .. your photo ..
In October, 2011, NASA's Operation IceBridge discovered a major rift in the Pine
Island Glacier in western Antarctica. Credit: NASA
It would be a calamity to lose the ice.
Join the InvestorsHub Community
Register for free to join our community of investors and share your ideas. You will also get access to streaming quotes, interactive charts, trades, portfolio, live options flow and more tools.
