Antarctic glaciers melting quicker than expected

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Thwaites Glacier: NASA

This is the third in a series of blogs covering some aspects of the extensive research on climate change carried out by NASA. This blog covers two major projects in West and East Antarctica.

West Antarctica

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Thwaites Glacier: NASA

A paper has just been published in Science Advances on the glaciers of West Antartica that has major implications for our understanding of climate change.

The paper is entitled Heterogenous retreat and ice melt of Thwaites Glacier, West Antarctica. The authors are Pietro Milillo, Eric Rignot (NASA Jet Propulsion Laboratory), P. Rizzoli, Jose Luis Bueso Bello, P. Prats-Iraola (German Aerospace Center), B. Scheuchl, Jeremy Mouginot, (University of California, Irvine).

The Antarctic Ice Sheet is changing rapidly and its melting is contributing to a rise in global sea levels. One section of the ice sheet – the Amundsen Sea Embayment (ASE) – is particularly important.  The Thwaites Glacier (about the size of Florida) accounts for a third of the mass loss from the ASE. The rate of ice discharge from the Glacier quadrupled in the period 2003 – 2010 to 9.5 Gt/year.

During 2016 and 2017, repeated InSar (interferometric synthetic-aperture radar) observations were made of the Glacier by the COSMO-SkyMed (CSK) satellite system. Details of all the different forms of satellite data collected and analysed are given in the paper.

The Glacier is disintegrating, and the study identified a huge cavity almost 300 m (1,000 ft) tall growing at the bottom of the Glacier.  This cavity previously contained 14 billion tonnes of ice. Most of this has melted over the last 3 years. As more heat and water get under the Glacier the quicker it melts. The melting of the Glacier currently accounts for about 4% of the rise in global sea levels. If the Glacier was to fully melt it would raise global sea levels by 0.65 m (2 ft).

The cavity was identified by the ice-penetrating radar used by the NASA IceBridge program that commenced in 2010. This is the largest airborne survey of the Earth’s polar ice ever carried out and provides 3-D images of the Arctic and Antarctic ice sheets, ice shelves and sea ice. The mapping takes place one a year – Greenland (March-May) and Antartica (October -November).

A new study, the International Thwaites Glacier Collaboration will carry out work on the Glacier in 2019-2020.  The project is a joint collaboration between the USA (National Science Foundation) and the UK (Natural Environment Research Council).

East Antarctica

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East Antarctica glaciers: NASA

East Antarctica has long been considered to be more stable than West Antarctica. However, recent mapping work by NASA has shown that over the last decade a number of glaciers have begun to melt.

The Totten Glacier (see above image) contains enough ice to raise sea levels by at least 3 m (9 ft).  The Glacier, and a number of smaller glaciers in the region, has started to melt as ocean temperatures rise.

A report on the East Antarctica glaciers was given at the Fall Meeting of the American Geophysical Union in Washington on 10 December 2018.  The work was carried out by NASA researchers Catherine Walker, Alex Gardner, Fernando Paulo and Johan Nilsson.

The work has included determining the rate of flow of the glaciers, along with satellite-determined altimetry measurements taken by ICESat (2003-2009) and CryoSat (2011 – present). This showed that the rate of lowering of Adams (Wilkes Land) Glaciers had doubled since 2009 to 0.24 m (0.8 ft) a year. Four glaciers in Vincennes Bay have lowered their surface height by 3 m (9 ft) since 2008.  Data from ice-penetrating radar (HICARS) was used to study the ice structure under the surface. 

The study concluded that changes in ocean temperatures were now having a measurable effect on the East Antartica glaciers. 

These are two significant studies that demonstrate the increasing effect that ocean warming is having on melting glaciers in Antarctica. 

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