The distribution and evolution of supraglacial lakes on the 79 ° N 1 Glacier ( northeast Greenland ) and interannual climatic controls 2 3

The Nioghalvfjerdsfjorden glacier (also known as 79 North Glacier) drains approximately 8% of the 11 Greenland ice sheet. Supraglacial lakes (SGLs), or surface melt ponds, are a persistent summertime feature, and are 12 thought to drain rapidly to the base of the glacier and influence seasonal ice velocity. However, seasonal development 13 and spatial distribution of SGLs in the northeast of Greenland is poorly understood, leaving a substantial error on the 14 estimate of melt water and its impacts on ice velocity. Using results from an automated detection of melt ponds, 15 atmospheric and surface mass balance modelling and reanalysis products, we investigate the role of specific climatic 16 conditions on melt onset, extent and duration from 2016 to 2019. The summers of 2016 and 2019 were characterised by 17 above average air temperatures, particularly in June, as well as a number of rainfall events, which led to extensive melt 18 ponds to elevations up to 1600 m. Conversely, 2018 was particularly cold, with a large accumulated snowpack, which 19 limited the development of lakes to altitudes less than 800 m. There is evidence of inland expansion and increases in the 20 total area of lakes compared to the early 2000s, as projected by future global warming scenarios. 21 22