Animation: Satellite images of ‘surging’ glaciers in Asia
A new study has created a series of animations that capture ‘surging’ glaciers in the Karakoram mountain range in Asia over 25 years, from 1990 to 2015.Glaciers are huge rivers of ice formed from snow compacted over many years. Powered by the sheer weight of ice they contain, they gradually slide down mountain sides and along valleys. Karakoram’s glaciers are well-known for ‘surging’. A surging glacier varies between long dormant periods of little change – lasting tens to hundreds of years – and short surging phases, where accumulated ice at higher elevations flows rapidly down to its front. Surging isn’t the glacier melting, but rather it’s a glacier’s way of evening itself out when it gets top-heavy.Active surging phases typically last a few months or several years, with flows up to a thousand times faster than usual. The transfer of ice means the top of the glacier thins while the front gets thicker – perhaps by as much as 200 metres. You can see surging glaciers in action in the animation below of the Panmah glacier, which is flowing from top to bottom down the middle of the image. On the right-hand side, there are five tributaries feeding into the Panmah glacier that suddenly shoot forwards – this is surging.The still image below the animation can help you spot what to look out for. The surging glaciers are marked with an orange “SG”.We can now see for the first time a large number of surging glaciers in interaction, clearly revealing that there are different types of surges – from fast and short pulses to slow and long-lasting advances – in a small region for glaciers with similar characteristics.Paul hopes his work will help improve understanding of what triggers these surges and how glaciers in the Karakoram mountain range are changing. The region’s glaciers are something of an outlier, says Paul, as most are stable or advancing, rather than retreating and shrinking like many around the world. Using animations will help scientists distinguish between a normal glacier melting and a surging glacier surging, he adds.
Main image: Baltoro glacier and its surrounding tributaries. Credit: Paul (2015).
Article information
Paul, F. (2015) Revealing glacier flow and surge dynamics from animated satellite image sequences: examples from the Karakoram, The Cryosphere, doi: 10.5194/tc-9-1-2015