ANTARCTIC WARMING ICE SHEETS & METHANE
Enormous amount of methane - research in Nature August 2012 projects the potential amount of methane hydrate and free methane gas beneath the Antarctic Ice Sheet could be up to 4 billion metric tons, a similar order of magnitude to some estimates made for Arctic permafrost. This is double atmospheric carbon. The predicted shallow depth of these potential reserves also makes them more susceptible to climate forcing than other methane hydrate reserves on Earth.
A NASA Project report documents methane hydrate in the Antarctic region.
There are methane hydrate deposits present in the continental shelf of the north-eastern extreme of the Antarctic Peninsula.
Methane hydrate deposits located at the shallow part of the continental shelf of the north-eastern Antarctic Peninsula were destabilized by the rise in temperature that resulted from the post-glacial transgression of the Antarctic Ocean. The presence of methane hydrates in this area is suggested by the identification of methane escapes, mostly detected in the Admiralty Sound area Valle et al. 1997, 2002). High concentrations of hydrocarbons, from methane to iso-penthane were detected in sea-bottom sediments from this area (Data Base of the Instituto Antartico Argentino). Additionally, the Bottom Simulating Reflector (BSR) at 680 m below the sea-bottom was shown by multichannel seismic survey at the continental margin of the South Shetland Islands (Camerlenghi & Lodolo 1994, Camerlenghi et al. 1994), suggesting that methane hydrate deposits are probably present in the sea-bottom sediments.
A NASA report of April 2012 explains that the deep waters round Antarctica are warming up. Warm ocean currents attacking the underside of ice shelves are the dominant cause of recent ice loss from Antarctica, a new study using measurements from NASA's Ice, Cloud, and land Elevation Satellite (ICESat) revealed.
An international team of scientists used a combination of satellite measurements and models to differentiate between the two known causes of melting ice shelves: warm ocean currents thawing the underbelly of the floating extensions of ice sheets and warm air melting them from above. The finding, published today in the journal Nature, brings scientists a step closer to providing reliable projections of future sea level rise.
The researchers concluded 20 of the 54 ice shelves studied are being melted by warm ocean currents. Most of these are in West Antarctica, where inland glaciers flowing down to the coast and feeding into these thinning ice shelves have accelerated, draining more ice into the sea and contributing to sea-level rise. This ocean-driven thinning is responsible for the most widespread and rapid ice losses in West Antarctica and the majority of Antarctic ice sheet loss during the period studied.
The East Antarctic ice sheet is larger and much thicker than the West Antarctic ice seet, which site on bed rock that is largely below sea level unlike the East Antarctic ice sheet. This makes the West ice sheet unstable to ocean warming, while the East ice sheet has been considered to be stable.
The Antarctic Ice Sheet extends almost 14 million square kilometers or 5.4 million square miles. larger than the United States. If the ice sheet melted, sea level would rise by about 60 meters (200 feet).
The continent of Antarctica holds 90% of the world's ice (6,400,000 cubic miles). About 60 percent of all fresh water on the Earth is held in the Antarctic ice sheet,
The Western Antarctic Peninsula has one of the world's highest increase in temperatures.
Antarctic ice loss and sea level rise
May 2015 Science Dynamic thinning of glaciers on the Southern Antarctic Peninsula Satellites have recorded a sudden dramatic change in the behaviour of glaciers on the Antarctica Peninsula, according to a Bristol University-led study. The ice streams were broadly stable up until 2009, since when they have been losing on the order of 56 billion tonnes of ice a year to the ocean. A 21 May UK Mail article describes the dramatic finding.
Research in 2012 found the rate of West Antarctic warming is double the estimated rate which is 3X the global averager warming rate. Over winter time the warming is even faster at 10X the global average.
NASA: Rate of Antarctic ice loss triples in a decade December 2014
The findings of the 21-year study by Nasa and the University of California, Irvine claim to provide the most accurate estimates yet of just how fast glaciers are melting in the Amundsen Sea Embayment.
They lost an average 83 gigatons per year (91.5 billion US tons), or the equivalent of losing the water weight of Mount Everest every two years.
Global warming caused the melt rate of glaciers in west Antarctica to triple in the past 10 years.
That surge means the glaciers lost a Mount Everest-sized amount of water every two years over the past 21 years, at roughly a mass of 91.5 billion tons per year, according to scientists at NASA and the University of California-Irvine.
Oct 2014 in Nature the Southern Ocean has been warming faster that previously estimated, as more heat has been added to the climate system than had been thought.
Mar 2015 Volume loss from Antarctic ice shelves is accelerating. Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 km3 per year for 1994-2003 to rapid loss of 310 ± 74 km3 per year for 2003-2012. West Antarctic losses increased by 70% in the last decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.
In May 2014 research discovered that the Western Antarctic Peninsula is in a state of irreversible collapse. It should take a long time to go but after it does the rest of the Antarctic ice sheet is expected to go too. Interview at AGU here
The concern has been the Ice collapsing into the sea with warming, but Antarctica also has methane hydrate which should be a far greater and sooner concern.
Before the climate cooled 35 million years ago, large amounts of organic matter were produced by abundant Antarctic plant growth and accumulated in Antarctic basins now covered with ice. Low oxygen conditions under the ice have been favorable for biological processes to convert organic matter into methane and for the ice to trap it.
The melting peripheral ice is exposing methane emitting organic material
Antarctic atmospheric methane shows the post 2007 renewed increase in methane as other latitudes do.
Methane Tracker shows the presence of Antarctic methane emissions (ClimateState 2013 ).
Aug. 28, 2013 East Antarctic Ice Sheet Could Be More Vulnerable to climate change.
May 2014 Irreversible collapse of West. Antarctic ice sheet underway
14 Feb 2020 How close is the West Antarctic ice sheet to a ‘tipping point’?
2 April 2018 Antarctica retreating across the sea floor
1 June 2017 Is the collapse of the West Antarctic Ice Sheet inevitable?
12 May 2014 Scientists say West Antarctic ice sheet “collapse is under way” as temperatures rise
Oct 2017 media article Forces collapsing W. Ant. ice sheet
May 2017 NY Times Antarctic Dispatches