The distribution and evolution of supraglacial lakes on the 79° N Glacier (northeast Greenland) and interannual climatic controls

Abstract. Together with two neighbouring glaciers, the Nioghalvfjerdsfjorden glacier (also known as 79 North Glacier) drains approximately 12–16 % of the Greenland ice sheet. Supraglacial lakes (SGLs), or surface melt ponds, are a persistent summertime feature, and are thought to drain rapidly to the base of the glacier and influence seasonal ice velocity. However, seasonal development and spatial distribution of SGLs in the northeast of Greenland is poorly understood, leaving a substantial error on the estimate of melt water and its impacts on ice velocity. Using results from an automated detection of melt ponds, atmospheric and surface mass balance modelling and reanalysis products, we investigate the role of specific climatic conditions on melt onset, extent and duration from 2014 to 2019. The summers of 2016 and 2019 were characterised by above average air temperatures, particularly in June, as well as a number of rainfall events, which led to extensive melt ponds to elevations over 1400 m. Conversely, 2018 was particularly cold, with a large, accumulated snowpack, which limited the development of lakes to altitudes less than 800 m. There is evidence of inland expansion and increases in the total area of lakes compared to the early 2000s, as projected by future global warming scenarios.