New Cause of Antarctic Glacier Acceleration Revealed
New research led by Hokkaido University has revealed a novel mechanism accelerating the movement of Antarctic glaciers towards the sea. The findings, published in the journal Nature Communications, show that surface meltwater is a key factor that has long gone undetected in the southern polar region.
Until now, the loss of Antarctic ice mass has been largely attributed to warming ocean temperatures melting the underside of ice shelves (floating ice layers). However, this study proves that surface meltwater caused by rising air temperatures also plays an active role in accelerating glacier flow.
The process begins when snow and ice on the surface melt to form ponds of water, which then seep through cracks in the ice via a process known as hydrofracturing. The water flows down until it reaches the glacier bed more than 550 metres deep, acting as a lubricant that reduces friction between the ice and the underlying rock.
Based on data from pressure sensors and subglacial cameras, the meltwater can support up to 97 per cent of the weight of the ice layer. This causes the speed of glacier flow towards the sea to increase by around 10 to 20 per cent during periods of intense melting or when rainfall occurs in the region.
This phenomenon has previously been observed more often in Greenland. The Antarctic findings disprove the assumption that the extreme cold of the southern pole could prevent a similar mechanism. Given that Antarctica holds 90 per cent of the world’s ice reserves, this acceleration of ice flow poses a serious threat of global sea-level rise.
A supporting study in the journal Nature Climate Change warns that this melting is highly likely to continue throughout this century, regardless of whether the Paris Agreement targets are met. The impact will be strongly felt in coastal regions in the form of increased risks of coastal flooding and erosion.
Scientists are now calling for more intensive long-term monitoring via satellites and subglacial sensors. This step is needed to improve the accuracy of sea-level rise projections, given that each glacier responds differently to changes in global temperatures. (Nature, ScienceDaily, and Phys.org/Z-10)