Satellite observes rapid ice shelf disintegration in Antarctic

April 5, 2012, European Space Agency
This image shows radar images from the Envisat satellite from 2002 to 2012 of the Larsen B ice shelf in Antarctica. Over the last decade, the ice shelf has disintegrated by 1790 sq km. Credit: ESA

One of the satellite's first observations following its launch on 1 March 2002 was of break-up of a main section of the Larsen B ice shelf in Antarctica – when 3200 sq km of ice disintegrated within a few days due to mechanical instabilities of the ice masses triggered by climate warming.

Now, with ten years of observations using its Advanced Synthetic Aperture Radar (ASAR), Envisat has mapped an additional loss in Larsen B's area of 1790 sq km over the past decade.

The Larsen Shelf is a series of three shelves – A (the smallest), B and C (the largest) – that extend from north to south along the eastern side of the Antarctic Peninsula.

Larsen A disintegrated in January 1995. Larsen C so far has been stable in area, but observations have shown thinning and an increasing duration of melt events in summer.

"Ice shelves are sensitive to atmospheric and to changes in ocean currents and temperatures," said Prof. Helmut Rott from the University of Innsbruck.

"The northern Antarctic Peninsula has been subject to atmospheric warming of about 2.5°C over the last 50 years – a much stronger warming trend than on global average, causing retreat and disintegration of ice shelves."

Larsen B decreased in area from 11512 sq km in early January 1995 to 6664 sq km in February 2002 due to several calving events. The disintegration in March 2002 left behind only 3463 sq km. Today, Envisat shows that only 1670 sq km remain.

Envisat has already doubled its planned lifetime, but is scheduled to continue observations of Earth's ice caps, land, oceans and atmosphere for at least another two years.

This ensures the continuity of crucial Earth-observation data until the next generation of satellites – the Sentinels – begin operations in 2013.

"Long-term systematic observations are of particular importance for understanding and modelling cryospheric processes in order to advance the predictive capabilities on the response of snow and ice to climate change," said Prof. Rott.

"Climate models are predicting drastic warming for high latitudes. The Envisat observations of the Larsen confirm the vulnerability of ice shelves to climatic warming and demonstrate the importance of ice shelves for the stability of glaciers upstream.

"These observations are very relevant for estimating the future behaviour of the much larger ice masses of West Antarctica if warming spreads further south."

Radars on Earth observation satellites, such as Envisat's ASAR, are particularly useful for monitoring polar regions because they can acquire images through clouds and darkness.

The Sentinel missions – being developed as part of Europe's Global Monitoring for Environment and Security (GMES) programme – will continue the legacy of radar .

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2.3 / 5 (9) Apr 05, 2012
I thought anything less than 30 years was considered weather and not climate. Since this is a ten year period I guess it's just weather.

Unless they really mean to say if things are warmer it's climate and if they're colder it's weather...
4.3 / 5 (11) Apr 05, 2012
I will edit it...
Since Larsen 'A' broke up in 1995, we have witnessed a steady decline in the surface area of Larsen 'B' amounting to almost 10,000 square KM due to an increase in the frequency of warm weather in the higher latitudes. We will not offically declare that the climate in the area is warmer, nor will we predict a pattern of continued loss, as predictions based on 17 years of observational data are tenuous at best. Clearly the ice has been collapsing in an effort to fortify it's base structure and then rebuild a stronger, larger shelf capable of holding way more books on how fossil fuels will save the environment.
1 / 5 (6) Apr 05, 2012
Should not the increasing weight of the ice and size of the ice shelf cause more and more collapse, until the base is solidified? And exactly how much has the sea level rising in the past 10-15 years of global warming? And how does this compare to predictions back then? We're they off by 10% 100% 1000% more?
4 / 5 (8) Apr 05, 2012
Should not the increasing weight of the ice and size of the ice shelf cause more and more collapse, until the base is solidified? And exactly how much has the sea level rising in the past 10-15 years of global warming? And how does this compare to predictions back then? We're they off by 10% 100% 1000% more?

Except in the past year or two, average sea level rise beat predictions.

Then again, we had several Very large Earthquakes in Japan and Chile in the past several years, which were large enough to change the Earth's axis. This may have screw up the reference points a bit and could explain the "slow down" in the past few years.

these ice sheets are NOT growing.

The are collapsing and disintegrating.

Look up the definition of the word "disintegrate".

It's ridiculous that two people on this thread already drew the conclusion, somehow, that the ice is increasing in size!

Disintegrate is to destroy something by breaking it up into parts, or in this case melting...
1 / 5 (9) Apr 05, 2012
The Larsen Ice Shelf is far up the Antarctica Peninsula, far from the main part of the continent.


Sea Ice is above average as well.


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