The evolution of Greenland’s supraglacial lakes, 2000-2019

Abstract:

Supraglacial lakes represent significant seasonal meltwater stores on the Greenland ice sheet, and their drainage provides conduits for lake and surface meltwater to be transferred to the ice sheet bed. The relationship of these lakes with ice sheet surface mass balance, firn density, location, and how these have changed through time therefore have direct implications for understanding meltwater routing, lake enhanced surface melt, and ice sheet dynamics. However, ice sheet scale observations at high temporal resolution are required to understand their spatially variable impacts and the controls on the evolution of lakes through time.

Here we present results of daily Greenland-wide observations of supraglacial lakes and drainages from 20 melt seasons (2000-2019) derived from red band MODIS Terra satellite data (250 m) using the Google Earth Engine cloud computing platform. We show that at an ice sheet scale, lakes have been increasing in number and area, while the number of drainages have also being increasing. The impact of this on contemporary and future surface meltwater routing and ice dynamics remains unclear.

The inland extent of the highest elevation lakes are also observed to be coincident with observations of the upper limits of spatially extensive ice slabs in the west and north-east of the ice sheet (c.f. MacFerrin et al., 2019). We therefore suggest that surface mass balance combined with firn density evolution will play a crucial role in limiting the future inland expansion of Greenland’s supraglacial lakes.