New
satellite maps show polar ice caps melting at 'unprecedented rate'
Scientists
reveal Greenland and Antarctica losing 500
cubic kms of ice
annually, reports Climate
News Network
New
elevation models of Antarctica (right) incorporates 61 million
measurements and Greenland 7.5 million measurements from ESA’s
CryoSat satellite collected throughout 2012. Photograph: ESA
1
September, 2014
German
researchers have established the height of the Greenland and
Antarctic ice caps with greater precision than ever before. The new
maps they have produced show that the ice is melting at an
unprecedented rate.
The
maps, produced with a satellite-mounted instrument, have elevation
accuracies to within a few metres. Since Greenland’s ice cap is
more than 2,000 metres thick on average, and the Antarctic bedrock
supports 61% of the planet’s fresh water, this means that
scientists can make more accurate assessments of annual melting.
Dr
Veit Helm and other glaciologists at the Alfred Wegener Institute’s
Helmholtz Centre for Polar and Marine Research in Bremerhaven,
Germany, report in the journal The Cryosphere that, between them, the
two ice sheets are now losing ice at the unprecedented rate of 500
cubic kilometres a year.
The
measurements used to make the maps were taken by an instrument aboard
the European Space Agency’s orbiting satellite CryoSat-2. The
satellite gets closer to the poles − to 88° latitude − than any
previous mission and traverses almost 16m sq km of ice, adding an
area of ice the size of Spain to the big picture of change and loss
in the frozen world.
CryoSat-2’s
radar altimeter transmitted 7.5m measurements of Greenland and 61m of
Antarctica during 2012, enabling glaciologists to work with a set of
consistent measurements from a single instrument.
Over
a three-year period, the researchers collected 200m measurements in
Antarctica and more than 14m in Greenland. They were able to study
how the ice sheets changed by comparing the data with measurements
made by Nasa’s IceSat mission.
Greenland’s
volume of ice is being reduced at the rate of 375 cubic km a year. In
Antarctica, the picture is more complex as the West Antarctic ice
sheet is losing ice rapidly, but is growing in volume in East
Antarctica.
Overall,
the southern continent − 98% of which is covered with ice and snow
− is losing 125 cubic km a year. These are the highest rates
observed since researchers started making satellite observations 20
years ago.
“Since
2009, the volume loss in Greenland has increased by a factor of about
two, and the West Antarctic ice sheet by a factor of three,” said
Angelika Humbert, one of the report’s authors.
Image
1. Temperature 09 08 2014 The temperature of the water coming through
the Bering Strait is darker green which is in the 50's.(F) The
lighter green is around freezing or above. See the scale.
Image
2 Sea Surface Temperature SSTA 09 08 2014. The former brown area on
the Laptev Sea is turning red which shows around a 7 (F) degree
anomaly. See the scale.
Sea ice wears white after Labor Day
September 2, 2014
The Arctic summer of 2014 is nearing an end. Overall, the rate of ice loss during August was near average. Regions of low concentration ice remain in the Beaufort and East Siberian seas that may yet melt out or compress by wind action. While the Northwest Passage continues to be clogged with ice and is unlikely to open, the Northern Sea Route along the Siberian coasts appears open except for some ice around Severnaya Zemlya. As the end of the southern winter draws closer, Antarctic sea ice extent remains higher than average.
Overview of conditions
Sea ice extent in August 2014 averaged 6.22 million square kilometers (2.40 million square miles). This is 1.00 million square kilometers (386,000 square miles) below the 1981 to 2010 August average, but well above the 2012 August average of 4.71 million square kilometers (1.82 million square miles). Extent was below average throughout the Arctic except for a region in the Barents Sea, east of Svalbard. The ice edge continued to retreat north of the Laptev Sea, and is now within 5 degrees latitude of the North Pole.
Conditions in context
August ice extent declined at an average rate of 54,300 square kilometers (21,000 square miles) per day. This was slightly less than the average rate for the month. Generally, the decline slows in August as the Arctic sun dips lower in the sky. Recent years have been an exception, with relatively fast ice loss rates in August.
August 2014 compared to previous years
Despite the near-average rate of decline in ice extent through the month, August 2014 ended up with the 7th lowest extent in the satellite record. It is 1.51 million square kilometers (583,000 square miles) above the record low for August 2012 and is also higher than August of 2007, 2008, 2010, 2011, and 2013. The monthly linear rate of decline for August over the satellite record is now 10.3 percent per decade.
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