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Related: About this forumLand-Facing, Southwest Greenland Ice Sheet Movement Decreasing
(Please note, source is NASA. Copyright concerns are nil.)
https://www.nasa.gov/feature/goddard/land-facing-southwest-greenland-ice-sheet-movement-decreasing
[font face=Serif]Oct. 28, 2015
[font size=5]Land-Facing, Southwest Greenland Ice Sheet Movement Decreasing[/font]
[font size=3]In the face of decades of increasing temperatures and surface melting, the movement of the southwest portion of the Greenland Ice Sheet that terminates on land has been slowing down, according to a new study being published by the journal Nature on Oct. 29.
Researchers derived their results by tracking ice sheet movement through Landsat satellite images taken from 1985 to 2014 across a roughly 3,088-square-mile (8000-square-kilometer) region in southwest Greenland. They found that, between 2007 and 2014, ice movement slowed in 84 percent of the study area, during a period of high surface melt, compared to the years between 1985 and 1994. The average slowdown was 12 percent, or 32.8 feet (10 meters) per year.
The finding is contrary to the widely held view that a greater amount of surface melting will result in faster-moving ice sheets, as the movement of both ocean- and land-terminating ice sheets is caused in part by surface meltwater, which makes its way to the bedrock through openings in the ice and acts as a lubricant. The amount of meltwater draining from the ice sheet in four out of the five years between 2007 and 2012 has been the most substantial of the last 50 years.
Researchers found that while the larger summertime meltwater volume of recent years has led to greater lubrication of the ice sheet base, speeding up its flow as expected, by the end of summer the meltwater has also established channels at the base that act as efficient drainage systems to lessen the water under the ice sheet, slowing it down by winter.
This suggests that further increases in melting will not cause these land-terminating margins of the ice sheet to speed up, said lead author Andrew Tedstone, a glaciologist at the University of Edinburgh, Scotland.
Nevertheless, it is unclear how much more slowdown we will see under the current and future melting conditions, said co-author Noel Gourmelen, University of Edinburgh. More research and observation are needed to determine this.
While these results may be viewed as good news for the Greenland ice sheet, they are offset by the fact that it is not the change in movement of the land- but rather the ocean-terminating portion of the ice sheet that is contributing to sea level rise.
The ongoing acceleration of both glacier surface melt volumes and the ice motion of ocean-terminating glaciers ensures that Greenlands contribution to sea level rise will likely increase in our warming world, said co-author Peter Nienow, University of Edinburgh.
[/font][/font]
[font size=5]Land-Facing, Southwest Greenland Ice Sheet Movement Decreasing[/font]
[font size=3]In the face of decades of increasing temperatures and surface melting, the movement of the southwest portion of the Greenland Ice Sheet that terminates on land has been slowing down, according to a new study being published by the journal Nature on Oct. 29.
Researchers derived their results by tracking ice sheet movement through Landsat satellite images taken from 1985 to 2014 across a roughly 3,088-square-mile (8000-square-kilometer) region in southwest Greenland. They found that, between 2007 and 2014, ice movement slowed in 84 percent of the study area, during a period of high surface melt, compared to the years between 1985 and 1994. The average slowdown was 12 percent, or 32.8 feet (10 meters) per year.
The finding is contrary to the widely held view that a greater amount of surface melting will result in faster-moving ice sheets, as the movement of both ocean- and land-terminating ice sheets is caused in part by surface meltwater, which makes its way to the bedrock through openings in the ice and acts as a lubricant. The amount of meltwater draining from the ice sheet in four out of the five years between 2007 and 2012 has been the most substantial of the last 50 years.
Researchers found that while the larger summertime meltwater volume of recent years has led to greater lubrication of the ice sheet base, speeding up its flow as expected, by the end of summer the meltwater has also established channels at the base that act as efficient drainage systems to lessen the water under the ice sheet, slowing it down by winter.
This suggests that further increases in melting will not cause these land-terminating margins of the ice sheet to speed up, said lead author Andrew Tedstone, a glaciologist at the University of Edinburgh, Scotland.
Nevertheless, it is unclear how much more slowdown we will see under the current and future melting conditions, said co-author Noel Gourmelen, University of Edinburgh. More research and observation are needed to determine this.
While these results may be viewed as good news for the Greenland ice sheet, they are offset by the fact that it is not the change in movement of the land- but rather the ocean-terminating portion of the ice sheet that is contributing to sea level rise.
The ongoing acceleration of both glacier surface melt volumes and the ice motion of ocean-terminating glaciers ensures that Greenlands contribution to sea level rise will likely increase in our warming world, said co-author Peter Nienow, University of Edinburgh.
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Land-Facing, Southwest Greenland Ice Sheet Movement Decreasing (Original Post)
OKIsItJustMe
Oct 2015
OP
TreasonousBastard
(43,049 posts)1. OTOH, if the increasing fresh water melt...
somehow contributes to a reversal of the Gulf Stream, we have a whole new set of problems.
Apparently, 20,000 years ago the Gulf Stream did actually reverse, although the are not sure of the cause. It did seem to have something to do with salt/fresh water imbalances, and it had a lot to do with that Ice Age.
OKIsItJustMe
(19,937 posts)2. Read more…
TreasonousBastard
(43,049 posts)3. Scary stuff, but...
We probably don't have to worry in our lifetimes.
Our grandkids, though... What world are we leaving them?
OKIsItJustMe
(19,937 posts)4. Study sheds light on Greenland Ice Sheet
http://www.ed.ac.uk/news/2015/greenland-291015
[font face=Serif][font size=5]Study sheds light on Greenland Ice Sheet[/font]
[font size=4]Parts of Greenlands ice sheet have been found to be less vulnerable to climate warming than was thought, research shows.[/font]
[font size=3]The discovery could have a small but beneficial impact on sea level forecasts.
Satellite images have revealed that despite dramatic increases in ice melt across Greenland in recent years, the speed of ice movement in some areas has slowed down rather than accelerated.
The finding, observed on a sector of the ice sheet that terminates on land rather than in the ocean, will help scientists improve predictions of how quickly Greenlands ice will be lost in a warming climate.
Until recently, scientists thought that the increased volumes of meltwater from Greenlands ice in response to climate warming would speed up the motion of all parts of the ice sheet by helping the ice slide more rapidly.
[/font][/font]
[font size=4]Parts of Greenlands ice sheet have been found to be less vulnerable to climate warming than was thought, research shows.[/font]
[font size=3]The discovery could have a small but beneficial impact on sea level forecasts.
Satellite images have revealed that despite dramatic increases in ice melt across Greenland in recent years, the speed of ice movement in some areas has slowed down rather than accelerated.
The finding, observed on a sector of the ice sheet that terminates on land rather than in the ocean, will help scientists improve predictions of how quickly Greenlands ice will be lost in a warming climate.
Until recently, scientists thought that the increased volumes of meltwater from Greenlands ice in response to climate warming would speed up the motion of all parts of the ice sheet by helping the ice slide more rapidly.
[/font][/font]