The onset of the ablation season in Greenland is defined as the first of at least three days in a row with a surface mass balance below -1 km³ (= -1 gigaton). In 2025, this was on 15 June, 2 days later than the median 1981-2010.
Top: SMB, 17 June 2025
Bottom: sum of daily SMBs since 1 Sep 2024
