Thursday, September 15, 2011 4:16:30 AM
Arctic sea ice volume reaches record low for second straight year
Sea ice volume in 2011 (blue line) relative to 2007 and the long-term mean.
(University of Washington)
By Jason Samenow
Posted at 02:07 PM ET, 09/14/2011
Arctic sea ice continues a long-term melting trend, setting new record lows for both volume and extent.
The University of Washington (UW) estimates [ http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ ] August sea ice volume was 62% below the 1979-2010 average. And data indicate the volume bottomed out [ http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png?%3C?php%20echo%20time%28%29%20? ] at a record low (as also documented on the excellent Arctic sea ice blog [ http://neven1.typepad.com/blog/2011/09/piomas-august-2011.html ]). The UW model [ http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ ] for estimating sea volume incorporates data from satellites, Navy submarines, moorings, and field measurements as well as atmospheric information.
News of the “unofficial” 2011 record for minimum Arctic sea ice voume follows acceptance of an article in the Journal of Geophysical Research [ http://psc.apl.washington.edu/wordpress/schweiger-2011/ ] which demonstrates the 2010 minimum sea ice volume was lower than 2007, the previous recordholder.
The sea ice volume metric is important because, unlike extent, it provides information on ice thickness and, thus, offers a more complete picture of what’s happening to the ice.
As for sea ice extent, the University of Bremen (in Germany) reports it reached a new historic minimum of 4.24 million square kilometers on September 8. In a press release [ http://www.iup.uni-bremen.de/seaice/amsr/minimum2011-en.pdf ] it stated:
It seems to be clear that this is a further consequence of the man-made global warming with global consequences.
An alternative estimate from the National Snow and Ice Data Center (NSIDC) indicates [ http://nsidc.org/arcticseaicenews/ ] that Arctic sea ice extent is currently at the second-lowest levels in the satellite record - very slightly higher than 2007.
NSIDC provides the following reasoning for the difference between its ranking and University of Bremen’s:
... data from the University of Bremen indicate that sea ice extent from their algorithm fell below the 2007 minimum. They employ an algorithm that uses high resolution information from the JAXA AMSR-E sensor on the NASA Aqua satellite. This resolution allows small ice and open water features to be detected that are not observed by other products. This year the ice cover is more dispersed than 2007 with many of these small open water areas within the ice pack.
Irrespective of whether the extent this year is lower than 2007 or not, NSIDC states: “...all of the data agree that Arctic sea ice is continuing its long-term decline.”
While the minimum sea ice extent and sea ice volume in August and September is an interesting indicator of climate change, the blog Real Climate recently posted a commentary [ http://www.realclimate.org/index.php/archives/2011/09/the-unnoticed-melt/ ] emphasizing the importance of sea ice trends earlier in the melt season:
This importance of sea-ice evolution during the early summer months is directly related to the role of sea ice as an efficient cooling machine: Because of its high albedo (reflectivity), sea ice reflects most of the incoming sunlight and helps to keep the Arctic cold throughout summer. The relative importance of this cooling is largest when days are long and the input of solar radiation is at its maximum, which happens at the beginning of summer. If, like this year, sea-ice extent becomes very low already at that time, solar radiation is efficiently absorbed throughout all summer by the unusually large areas of open water within the Arctic Ocean.
Our AmazingPlanet.com [ http://www.ouramazingplanet.com/arctic-sea-ice-record--2000/ ] has a succinct explanation for the implications of the declining sea ice:
Receding sea-ice cover can disrupt indigenous people’s way of life and threaten animals like polar bears and walruses. The loss of the “refrigerator” on top of the world can alter weather patterns elsewhere in the world. And once ice is lost it becomes more difficult to replace because light can then reach the ocean, which absorbs it and warms.
A well-documented potential beneficial impact of melting ice is the opening of new navigation routes throug the Arctic.
© 2011 The Washington Post
http://www.washingtonpost.com/blogs/capital-weather-gang/post/arctic-sea-ice-volume-reaches-record-low-for-second-straight-year/2011/09/13/gIQAVorKSK_blog.html [with comments]
===
Dire warning over Arctic sea ice melt
Ice thickness is just as important or more so in helping understand what is happening in the far north
Photo: AP/John McConnico
Sea-ice coverage across the Arctic Ocean has dwindled to its second-lowest level since satellite records started in 1979, the National Snow and Ice Data Centre said, days after another study said ice melt was at its worst levels ever.
8:00AM BST 14 Sep 2011
Areas of the Arctic with at least 15 per cent sea-ice as of Saturday totalled 1.68 million square miles, slightly above the record-low of 1.61 million square miles recorded in 2007.
Yet to be determined is whether the sea-ice cover will be the lowest for the year. Annual minimums are usually reached around mid-September.
"We're getting close, but there's still the potential for further loss of ice," said Walt Meier, a research scientist at the Boulder, Colorado-based National Snow and Ice Data Centre.
Ice coverage could diminish either through more melt or from winds or both, Mr Meier said. However, some areas, including those near the North Pole, were showing signs of ice growth, he said.
"Probably there's a little bit of both going on - there's melting and refreezing," he said.
At least one other institution has reported that this year's Arctic ice coverage was the lowest on record. A report issued last week by the University of Bremen in Germany said sea-ice coverage on Sept. 8 fell below the 2007 minimum.
The University of Bremen researchers use finer-resolution measurements that can better distinguish smaller areas of ice and open water, Meier said. But that university's methodology also has some drawbacks, he said.
Under either measurement, however, Arctic ice cover has diminished dramatically over recent decades. Saturday's coverage, as measured by the National Snow and Ice Data Centre, was only about two-thirds the average coverage measured from 1979 to 2000.
Reduced sea ice is believed to have cascading impacts on climate in the circumpolar north and even lower latitudes.
According to an academic study released on Tuesday by the US Geological Survey, Yupik Eskimo residents in southwestern Alaska are living with some of those affects.
The study, published in the current edition of the journal Human Organisation, examined observations of elders and longtime hunters in two Lower Yukon River villages.
The residents detailed dramatic changes over the years in river-ice thickness, a public-safety risk because no roads connect villages in that part of Alaska, and residents in winter travel over river ice.
The residents also testified to changing ranges for several animals, particularly moose and beavers, changes in vegetation and concerns about reduced availability of driftwood that used to be pushed downstream by powerful currents of spring meltwater.
© Copyright of Telegraph Media Group Limited 2011
http://www.telegraph.co.uk/earth/environment/climatechange/8761445/Dire-warning-over-Arctic-sea-ice-melt.html [with comments]
Sea ice volume in 2011 (blue line) relative to 2007 and the long-term mean.
(University of Washington)
By Jason Samenow
Posted at 02:07 PM ET, 09/14/2011
Arctic sea ice continues a long-term melting trend, setting new record lows for both volume and extent.
The University of Washington (UW) estimates [ http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ ] August sea ice volume was 62% below the 1979-2010 average. And data indicate the volume bottomed out [ http://psc.apl.washington.edu/wordpress/wp-content/uploads/schweiger/ice_volume/BPIOMASIceVolumeAnomalyCurrentV2.png?%3C?php%20echo%20time%28%29%20? ] at a record low (as also documented on the excellent Arctic sea ice blog [ http://neven1.typepad.com/blog/2011/09/piomas-august-2011.html ]). The UW model [ http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/ ] for estimating sea volume incorporates data from satellites, Navy submarines, moorings, and field measurements as well as atmospheric information.
News of the “unofficial” 2011 record for minimum Arctic sea ice voume follows acceptance of an article in the Journal of Geophysical Research [ http://psc.apl.washington.edu/wordpress/schweiger-2011/ ] which demonstrates the 2010 minimum sea ice volume was lower than 2007, the previous recordholder.
The sea ice volume metric is important because, unlike extent, it provides information on ice thickness and, thus, offers a more complete picture of what’s happening to the ice.
As for sea ice extent, the University of Bremen (in Germany) reports it reached a new historic minimum of 4.24 million square kilometers on September 8. In a press release [ http://www.iup.uni-bremen.de/seaice/amsr/minimum2011-en.pdf ] it stated:
It seems to be clear that this is a further consequence of the man-made global warming with global consequences.
An alternative estimate from the National Snow and Ice Data Center (NSIDC) indicates [ http://nsidc.org/arcticseaicenews/ ] that Arctic sea ice extent is currently at the second-lowest levels in the satellite record - very slightly higher than 2007.
NSIDC provides the following reasoning for the difference between its ranking and University of Bremen’s:
... data from the University of Bremen indicate that sea ice extent from their algorithm fell below the 2007 minimum. They employ an algorithm that uses high resolution information from the JAXA AMSR-E sensor on the NASA Aqua satellite. This resolution allows small ice and open water features to be detected that are not observed by other products. This year the ice cover is more dispersed than 2007 with many of these small open water areas within the ice pack.
Irrespective of whether the extent this year is lower than 2007 or not, NSIDC states: “...all of the data agree that Arctic sea ice is continuing its long-term decline.”
While the minimum sea ice extent and sea ice volume in August and September is an interesting indicator of climate change, the blog Real Climate recently posted a commentary [ http://www.realclimate.org/index.php/archives/2011/09/the-unnoticed-melt/ ] emphasizing the importance of sea ice trends earlier in the melt season:
This importance of sea-ice evolution during the early summer months is directly related to the role of sea ice as an efficient cooling machine: Because of its high albedo (reflectivity), sea ice reflects most of the incoming sunlight and helps to keep the Arctic cold throughout summer. The relative importance of this cooling is largest when days are long and the input of solar radiation is at its maximum, which happens at the beginning of summer. If, like this year, sea-ice extent becomes very low already at that time, solar radiation is efficiently absorbed throughout all summer by the unusually large areas of open water within the Arctic Ocean.
Our AmazingPlanet.com [ http://www.ouramazingplanet.com/arctic-sea-ice-record--2000/ ] has a succinct explanation for the implications of the declining sea ice:
Receding sea-ice cover can disrupt indigenous people’s way of life and threaten animals like polar bears and walruses. The loss of the “refrigerator” on top of the world can alter weather patterns elsewhere in the world. And once ice is lost it becomes more difficult to replace because light can then reach the ocean, which absorbs it and warms.
A well-documented potential beneficial impact of melting ice is the opening of new navigation routes throug the Arctic.
© 2011 The Washington Post
http://www.washingtonpost.com/blogs/capital-weather-gang/post/arctic-sea-ice-volume-reaches-record-low-for-second-straight-year/2011/09/13/gIQAVorKSK_blog.html [with comments]
===
Dire warning over Arctic sea ice melt
Ice thickness is just as important or more so in helping understand what is happening in the far north
Photo: AP/John McConnico
Sea-ice coverage across the Arctic Ocean has dwindled to its second-lowest level since satellite records started in 1979, the National Snow and Ice Data Centre said, days after another study said ice melt was at its worst levels ever.
8:00AM BST 14 Sep 2011
Areas of the Arctic with at least 15 per cent sea-ice as of Saturday totalled 1.68 million square miles, slightly above the record-low of 1.61 million square miles recorded in 2007.
Yet to be determined is whether the sea-ice cover will be the lowest for the year. Annual minimums are usually reached around mid-September.
"We're getting close, but there's still the potential for further loss of ice," said Walt Meier, a research scientist at the Boulder, Colorado-based National Snow and Ice Data Centre.
Ice coverage could diminish either through more melt or from winds or both, Mr Meier said. However, some areas, including those near the North Pole, were showing signs of ice growth, he said.
"Probably there's a little bit of both going on - there's melting and refreezing," he said.
At least one other institution has reported that this year's Arctic ice coverage was the lowest on record. A report issued last week by the University of Bremen in Germany said sea-ice coverage on Sept. 8 fell below the 2007 minimum.
The University of Bremen researchers use finer-resolution measurements that can better distinguish smaller areas of ice and open water, Meier said. But that university's methodology also has some drawbacks, he said.
Under either measurement, however, Arctic ice cover has diminished dramatically over recent decades. Saturday's coverage, as measured by the National Snow and Ice Data Centre, was only about two-thirds the average coverage measured from 1979 to 2000.
Reduced sea ice is believed to have cascading impacts on climate in the circumpolar north and even lower latitudes.
According to an academic study released on Tuesday by the US Geological Survey, Yupik Eskimo residents in southwestern Alaska are living with some of those affects.
The study, published in the current edition of the journal Human Organisation, examined observations of elders and longtime hunters in two Lower Yukon River villages.
The residents detailed dramatic changes over the years in river-ice thickness, a public-safety risk because no roads connect villages in that part of Alaska, and residents in winter travel over river ice.
The residents also testified to changing ranges for several animals, particularly moose and beavers, changes in vegetation and concerns about reduced availability of driftwood that used to be pushed downstream by powerful currents of spring meltwater.
© Copyright of Telegraph Media Group Limited 2011
http://www.telegraph.co.uk/earth/environment/climatechange/8761445/Dire-warning-over-Arctic-sea-ice-melt.html [with comments]
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"Eternal vigilance is the price of Liberty."
from John Philpot Curran, Speech
upon the Right of Election, 1790
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