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2 June 2017

Future Brighter than Expected for Thwaites Glacier, NASA Study Reveals

The Thwaites Glacier of West Antarctica is massive in both scale and importance, covering an area roughly the size of Washington (70,000 square miles/182,000 square kilometres) and currently accounting for approximately 1% of global sea level rise. As such, understanding how it is expected to react to future changes in climate is of the utmost importance, particularly when you bear in mind that satellite measurements have confirmed that the glacier’s rate of ice loss has doubled since the 1990s, giving the glacier the potential to add several inches to global sea levels.

To this end, a new NASA-conducted study published in the journal Geophysical Research Letters has provided some intriguing new insights into the behaviour of the Thwaites Glacier which, rare as this may be these days when discussing the impact of climate change on such features, actually provides some relatively promising and uplifting news.

The Thwaites Glacier   - Img: NASA/James Yungel
As it turns out, the glacier’s total predicted ice loss over the next 50 years has been overestimated by about 7%, due to numerical studies used in previous studies overestimating the speed at which ocean water is able to melt the glacier from below.

The new study, led by Helene Seroussi of NASA’s Jet Propulsion Laboratory, combines two computer models, one of the Antarctic ice sheet and one of the Southern Ocean, and allows them to interact and thereby influence each other over the course of the experiment. Previous studies of the glacier have solely used a model of the ice sheet, leading to the aforementioned inaccuracy. The new combined model is referred to by scientists as a ‘coupled model’.

The reason as to why ocean water has a larger impact upon the Thwaites Glacier than it does on others is due to the terrain upon which the glacier travels. While the beds of most glaciers travel much like a river from a high point down to a low point at the coast, the Thwaites Glacier does the reverse. The bedrock under the glacier’s ocean front sits at a higher elevation than that further inland, forcing the glacier to flow uphill and creating a drop below the main body. The ice loss which has already occurred on the Thwaites Glacier means that it is no longer attached to the bedrock; instead it floats upon the water. This creates a passageway via which ocean water can reach the underside of the glacier and cause an accelerated rate of ice loss as a result.

In the region of Antarctica where the Thwaites Glacier is located, warm, heavily-salinated ocean currents circulate near land, which allows warm water to seep below the glacier, melting it from below. However, previous studies have assumed that the rate of melting would remain as it is now, an assertion which is contradicted by Seroussi’s coupled model. Seroussi’s model suggests that due to how water circulation is restricted in these narrow spaces, the ice will actually melt much slower than previously expected.

“Our results shift the estimates for sea level rise to smaller numbers regardless of the scenario,” Seroussi concludes.

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.