ice sheet

West Antarctic ice sheet melting accelerates over last 4 years

By Tim Radford. The rate of ice loss from the West Antarctic appears to have accelerated sharply in the last four years, European scientists say.

LONDON, 20 December - Ice is being lost over the West Antarctic ice sheet at a faster rate. The European Space Agency’s Cryosat - a satellite with a radar altimeter that can peer through the clouds and see in the dark - has confirmed  that 150 cubic kilometres of ice are drifting into the Southern Ocean each year: a much faster rate than the calculation for 2010.

After observations between 2005 and 2010, gathered by 10 different satellite missions, Antarctic scientists and oceanographers calculated that the melting of ice from the West Antarctic peninsula was causing global sea levels to rise by 0.28mm a year. The latest survey suggests this rate is 15% higher.

Ice Sheets and Sea level: what the past tells us is likely

Watch this informative video By Peter Sinclair and the Yale Forum on Climate Change and the Media on ice sheet collapse and sea level rise and past climates.

"We are still potentially underestimating the instability of the ice sheets" informs Stefen Rahmstorf, Professor of Physics of the oceans from Postdam University. "The IPCC has greatly revised it's estimates of how unstable the Greenland ice sheet was"

Dr Richard Alley in a graph illuminates that on current CO2 levels we can expect sea level rise to impact 10 per cent of the Earth's population, hundreds of millions of people. He says in the video that "Greenland is very tightly tied to temperature, and if it gets too hot, it goes away".

Volcanic activity adds further to instability of West Antarctic Ice Sheet

Volcanic activity detected near the Executive Committee range in Marie Byrd Land in West Antarctica adds another factor to the instability of the West Antarctic Ice Sheet (WAIS). A small eruption under the ice could result in melt water adding substantial lubrication to the bottom of a portion of the ice sheet, speeding up the ice stream discharge into the Ross Sea.

Greenland melting occurring during winter with above average temperatures

Satellite data for the first several weeks of 2013 is showing that melting is occurring in south east Greenland. In summer this would be expected, but January-February is the dead of winter. Some portions of Greenland have experienced more than 30 days of melting since the start of this year, a worrying trend.

According to email correspondence with Ted Scambos from National Snow and Ice Data Centre (NSIDC) sent to Tom Yulsman, all of Greenland has been 2 to 6 degrees C warmer than the 30 year mean. Tom quotes Ted Scambos on his blog: "Air temperatures along the southeastern coast for the period Feb 10 – 15 are running 2 to 6 C above normal. Nuuk, the capital, on the very southern west coast, is currently just a couple of degrees below freezing."

Related: Is Climate Change causing an exponential rate of Ice sheet Mass Loss, sea level rise? | Global Warming threshold for Greenland Ice Sheet collapse reduced to 1.6 degrees C

Greenland winter melting Jan Feb 2013

Greenland winter melting Jan Feb 2013

Images from the NSIDC 19 February Greenland Ice Sheet Today website

Is Climate Change causing an exponential rate of Ice sheet Mass Loss, sea level rise?

Greenland Ice Mass change rate 2012Greenland Ice Mass change rate 2012Climate scientist James Hansen and his colleague Makiko Sato have released a new discussion paper with updated data on ice sheet mass loss from Greenland and Antarctica, with implications for possible multi-metre sea level rise this century. It makes for some interesting reading - there is a link to Hansen's website and the paper at the end.

The thesis that Hansen has put forward for several years is that Ice Sheet collapse is a non-linear process: that with the inclusion of amplifying climate feedbacks it is likely to follow an exponential rate of acceleration - a doubling rate. It might be a 10 year doubling time, or less. This will lead to extensive sea level rise, perhaps in the order of 5 metres this century.

Related: Matt Owens on Direct impacts to US GDP: that direct losses could top 1/4 trillion per year during 2040-2050

Greenland Ice Mass change rate 2012

Greenland Ice Mass change rate 2012

From Hansen and Sato 2012 - Dec. 26, 2012: Update of Greenland Ice Sheet Mass Loss (PDF). Discussion of how the loss rate is changing.- Fig. 1.

Global Warming on West Antarctic Ice Sheet three times the global average

Original article from San Fransisco Bay Area Indymedia, Dec 23rd, 2012 7:16 PM: The West Antarctic Ice Sheet is warming at three times the global average, according to temperature measurements at Byrd Polar Station. This has implications for the melting of the West Antarctic Ice sheet (WAIS) and sea level rise.


Related: Global warming in Antarctica: Thwaites and Pine Island Glaciers | Waking the giant: Global Warming in the Weddell Sea | Southern Ocean warming impact on Antarctic Ice Sheet and global sea level

Greenland experiences 97% surface melt

Greenland experiences 97% surface melt

Image Caption (NASA): Extent of surface melt over Greenland's ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12.

Are we close to a tipping point? Greenland Ice Sheet suffers unprecedented surface melt

Surface melt on the Greenland ice sheet reached up to 97% of the ice sheet area by July 12, an unprecedented level of melting, according to readings gathered and cross-referenced from three different satellites by several scientists.

Satellite measurements showed that about 40 percent of the ice sheet had undergone thawing at or near the surface on July 8, but over the subsequent 4 days the melting had dramatically accelerated to cover an estimated 97 percent of the ice sheet surface by July 12. This was the largest area seen thawing ever measured on the Greenland ice sheet by satellite measurements.

Update: Arctic Sea Ice Extent drops to lowest on record and still shrinking

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