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Lakes Engagement Project

Thursday, April 7th, 2022

At 1.71 million square kilometres, almost 80% of Greenland’s surface is covered in a 2 to 3 kilometre-thick ice sheet. Within it, 8% of the planet’s freshwater resides. In contrast to almost all other landmasses, we do not want to access Greenland’s freshwater stores; rather, we want to preserve it.

Anthropogenic global warming is the most important problem of our generation, and Greenland’s ice shee

t is suffering because of it. Seasonally, when temperatures rise above 0°C, the surface of Greenland’s ice sheet melts. Global warming is elongating this period, as highlighted in July of 2012 when much as 98% of the ice sheet’s surface was covered in meltwater. Around the coastline of Greenland, where gravity-driven glacial motion is most prominent, shear stresses from adjacent ice of contrasting velocities form crevasses. Meltwater can collect in these crevasses to form supraglacial lakes.

Supraglacial lakes are temporary basins to enormous supplies of freshwater, and pose two problems to global sea levels. Firstly, as they are, these lakes absorb solar radiation (i.e. heat) more readily than ice, and so accelerate glacial melting. Secondly, when a crevasse that is holding water erodes into a nearby moulin (glacial water shaft), supraglacial lakes containing gigalitres of water can completely drain in as little as a few hours.

The draining of a supraglacial lake coincides with the plummeting of water from the surface of the ice sheet to its base. At this level, subglacial meltwater can travel along the ice bed and underneath the ice sheet itself. Just as heavy rain causes cars to aquaplane on otherwise safe roads, meltwater can cause the termini of Greenland’s ice sheet to ‘slip’ towards the Arctic Ocean. By accelerating glacial movement, in a process known as basal sliding, meltwater increases waterline calving, the number of melting icebergs, and the global sea level.

To better understand this process, and its impact in rising sea levels, the Lakes Engagement Project seeks to engage visitors with software used to identify supraglacial lakes from satellite images of Greenland. These images span nearly a decade, and could tell us whether the annual number, or size, of Greenland’s ice lakes is changing. Our software is not yet optimized, however, and can misidentify shadows as ice lakes. Humans, on the other hand, use holistic thinking to know that shadows are cast from sunlit mountains, and are not lakes.

Discerning what is and isn’t a lake is the crux of our software’s issue, but with the help of the public, we may be able to better understand and convey how manmade global warming is adversely affecting Greenland’s ice sheet, and the consequences it has to global sea level rise.