Ice sheet melting faster than predicted

Antarctica boasts the largest mass of ice on earth, a colossal 27 million km3, comprised of three vast ice sheets: the East, the West and the Antarctic Peninsula. With warming seas and climbing temperatures, scientists focused their attention on the West Antarctic Ice Sheet, due to its vulnerability to rising water temperatures, being grounded far below sea level.

However, new research from Imperial College institutions in Australia, New Zealand and the US, reveal that the East Antarctic Ice Sheet is becoming alarmingly unstable. The EAIS holds even more ice than its Western counterpart, which is already beginning to collapse, and is predicted to contribute four metres in sea level rise.

The new cause for concern is the circulating warm water beneath a critical part of the Totten Glacier, one of many glaciers supporting the EAIS. This water is contributing to the melting of the glacier, and if it retreats a mere 150km more, it will trigger a rapid retreat of up to 300km due to the interaction with the sedimentary rocks below. Now, this 300km retreat may take several centuries, but once this threshold is crossed, the stability of the rest of the glacier, moreover the East Antarctic Ice Sheet, will be left to the mercy of the elements.

The retreat would become unstoppable, causing a sea level rise of around 2.9m from this glacier alone. The theory behind this pattern of rapid retreat comes from studying the geology of the rocks below the glacier. Following patterns of retreat and advance, evidence from geophysical surveys suggests much more rapid retreat when the ice hits more unstable regions of rock. These unstable regions could again come into play with the increasing rate of retreat.

The scale of the EAIS and Totten makes this discovery particularly concerning. Totten itself is around 220,000 square miles in area, bigger than the US State of California. In some parts the ice is 2.5 miles thick, so the potential loss of ice is massive. However, Totten is dwarfed by the size of the ice sheet it supports: the EAIS makes up two thirds of the entire Antarctic ice sheet.

Co-author of the study, Professor Martin Siegert, emphasises the need for concern. “The East Antarctic Ice Sheet is by far the largest mass of ice on Earth, so any small changes have a big influence globally".