Climate change is driving melting at world’s thickest ice sheet: alarming new evidence

Parliamentary Yearbook examines research by British scientists which suggests that glaciers along 5,400 km of the edge of the East Antarctic ice sheet are systematically changing in line with changes in temperature. 

There is significant concern about the impact that the earth’s increased temperature - over the last 100 years – is exerting on our planet.  As rising temperatures affects glaciers and icebergs, the ice caps at the Earth’s two Polar Regions - the North Pole and South Pole - are exposed to an increasing risk of melting which will cause the oceans to rise with devastating consequences.

The polar region at the northernmost part of the Earth is of course known at the ‘Arctic’.  This includes the Arctic Ocean and parts of Canada, Russia, the United States (Alaska), Denmark (Greenland), Norway, Sweden, Finland and Iceland.  The Arctic Ocean in this area is covered by floating pack ice (sea ice), surrounded by treeless frozen soil. Known as permafrost, this is soil which has been at or below the freezing point of water for two or more years.  The average temperature for the warmest Arctic month is -10 degrees Celsius.

Large areas of the ice pack can be up to 3-4 metres thick, with ridges up to 20 metres. Despite this, ice at this Arctic end of the world is not nearly as thick as the equivalent polar region at the opposite southernmost end of the Earth, known of course as the ‘Antarctic’.

The Antarctic consists of the continent of Antarctica and ice shelves, waters, and island territories in the South Ocean.  In contrast with floating pack ice (this “sea ice” is typically less than 3 metres thick), an ice shelf is a much thicker floating platform of ice (100-1000 metres thick) that forms where a glacier or ice sheet flows down a coastline onto the ocean surface.

For some time, scientists have been concerned about the threat to sea levels from melting in the Arctic region.  Despite the fact that Arctic ice has a natural melting cycle - in which half of the ice pack melts away in the summer, to freeze back again in the winter - a previous study revealed that the 3-4 metre thick ice is melting so fast that half of it will disappear by the end of the century.  Further studies have suggested that the whole northern Arctic region could be without ice during the summer months in less than a century.

Until now scientists have largely dismissed concerns about melting in  the world’s biggest ice sheet located in the South, namely at the East Antarctic, due to the extremely cold temperatures in that region (which can drop below minus 30 degrees Celsius at the coast). However, a study by British scientists has now identified three significant patterns in the size of glaciers in this region which coincide with changes in temperature.

A team from the Department of Geography at Durham University collated measurements from 175 ‘ocean-terminating glaciers’ - where they meet the sea - along 5,400km of the   East Antarctic Ice Sheet’s coastline.  The measurements were obtained from declassified spy satellite imagery, covering almost half a century (from 1963 - 2012). The data was used to create the first long term record of changes at glacier edges in this region.

The research identified three significant patterns:  

       The 1970s-80s, when temperatures were rising, and most glaciers retreated

·            In the 1990s, when temperatures decreased, most glaciers advanced

·         In the 2000s, when temperatures increased and then decreased, there was a more even mix of retreat and                   advance

Lead researcher, Dr Chris Stokes, noted that the patterns identified were distinct from the natural cycles of advance and retreat triggered by the process of large icebergs breaking off at the terminus which happens independently of climate change.

Commenting on the patterns, he said: “It was a big surprise therefore to see rapid and synchronous changes in advance and retreat, but it made perfect sense when we looked at the climate and sea-ice data.”

Dr Stokes cautioned that:  “If the climate is going to warm in the future, our study shows that large parts of the margins of the East Antarctic Ice Sheet are vulnerable to the kinds of changes that are worrying us in Greenland and also in West Antarctica - acceleration, thinning and retreat.”

The alarming picture is of melting of both polar regions in proximal time frames under the impact of climate change. Welcome to water world.

This research has been published in the journal Nature.