Greenland’s ice is Earth’s second-largest frozen reservoir
The Greenland ice sheet averages 1,673 metres thick and exceeds 3,488 metres at its deepest, running almost 2,900 kilometres north–south. Only Antarctica holds more ice—and Greenland’s glaciers have existed in major form for at least 18 million years.
Snow stacks year after year until weight turns firn into glacier ice that creeps unless coastal ranges brace it. Eleven earlier advances shoved ice past those barriers by as much as 120 kilometres. Northwest and southeast gaps are today’s main vents where outlet tongues calve, so geometry matters as much as air temperature when mass leaves the island.
Winter once rebuilt what summer shaved. Since 1996 accumulation has lagged ablation, and melt runs two to five times the pre-1850 pace. The 1970s were the last decade of net gain; by 2022 losses had stacked for twenty-six straight years amid the warmest millennium temperatures. From 1992 to 2018 roughly 3,902 gigatonnes departed—about 0.13 percent of total mass—with half that drop packed into eight years. Outlet glaciers alone may explain half to two-thirds of observed decline since the 1980s.
Complete melt of roughly 2.9 million cubic kilometres would raise oceans by about 7.4 metres. A Paris-aligned path under 2 °C still implies around six centimetres from this sheet alone by century’s end, while lasting warmth between about 1.7 and 2.3 °C risks locking irreversible decline. Labrador Sea sediments and ice cores show southern ice nearly gone around 400,000 years ago. Beneath the white lid sit mountains and lake basins; geothermal pockets can keep basal water liquid, speeding erosion while summit ice sometimes freezes to ancient soils that drillers recover. Second place among ice sheets still means planetary leverage.
Source: Greenland ice sheet
