miles) occurred in both June and July, due to cloud cover and high temperatures. In August 2020, scientists reported that the Greenland ice sheet lost a record amount of 532 billion metric tons of ice during 2019, surpassing the old record of 464 billion metric tons in 2012 and returning to high melt rates, and provide explanations for the reduced ice loss in 2017 and 2018. A study published in 2020 estimated, by combining 26 individual estimates of mass balance derived by tracking changes in Greenland's ice sheet volume, speed and gravity as part of the Ice Sheet Mass Balance Inter-comparison Exercise, that the Greenland Ice Sheet had lost a total of 3,902 gigatons (Gt) of ice between 1992 and 2018 (approximately 0.13% of its mass). The rate of ice loss has increased over time from 26 ± 27 Gt/year between 1992 and 1997 to 244 ± 28 Gt/year between 2012 and 2017 with a peak mass loss rate of 275 ± 28 Gt/year during the period 2007 and 2012. In July 2021, a new surge of widespread melting began, covering 340,000 square miles of the ice sheet, and melting more than 8 billion tons of ice per day for several days. In August 2021, as high temperatures continued over Greenland, with the melt extent at 337,000 square miles, rain fell for 13 hours at Greenland's Summit Station (at 10,551 feet elevation.) Researchers had no rain gauges to measure the rainfall, because temperatures at the summit have risen above freezing only three times since 1989 and it had never rained there before. Future ice loss Due to the enormous thickness of the central Greenland ice sheet, even the most extensive melting event can only affect a small fraction of it before the start of the freezing season. In scientific literature, they are described as "short-term variability": a 2020 paper found that the current models underestimate the extent and frequency of such events, meaning that the ice sheet decline in Greenland and Antarctica tracks worst-case scenarios of the IPCC Fifth Assessment Report's sea-level rise projections, However, even those worst-case scenarios only involve a minor portion of the ice sheet during the 21st century: in 2021, the IPCC Sixth Assessment Report estimated that under SSP5-8.5, the scenario associated with the highest global warming, Greenland ice sheet melt would add around to the global sea levels (with a likely (17%-83%) range of and