In a new study, scientists have found that atop the coastal Langhovde Glacier in East Antarctica’s Dronning Maud Land, large numbers of “supraglacial” or meltwater lakes have been forming — nearly 8,000 of them in summer between the year 2000 and 2013. Moreover, in some cases, just as in Greenland, these lakes appear to have then been draining down into the floating parts of the glacier, potentially weakening it and making it more likely to fracture and break apart.
This is the first time that such a drainage phenomenon has been observed in East Antarctica, the researchers say — though it was previously spotted on the warmer Antarctic Peninsula and likely part of what drove spectacular events like the shattering of the Larsen B ice shelf in 2002.
Mounting evidence suggests one reason that Greenland has been melting so fast lately is precisely these kinds of lakes. In the summer as air temperatures warm, lakes form on top of the ice sheet, and on its finger-like glaciers that extend outwards into deep ocean fjords.
The occurrence of these lakes was, not surprisingly, strongly related to surface air temperatures — they formed when temperatures rose above zero Celsius, or, above freezing, and formed most frequently in the summer of 2012-2013, which saw 37 days with temperatures above the freezing point.
The appearance of these lakes, unsurprisingly, is correlated directly with the air temperature in the region, and the maximum number of lakes, and the total area of the lakes, as well as the depth of the lakes, peak when the air temperatures peak.
When glaciers lose large parts of their ice shelves, they become less stable and flow faster towards the ocean, contributing to an increased rate of global sea level rise.