Greenland and Antarctica lost about 11.3 trillion metric tonnes of ice between 1979 and 2023, contributing roughly 3.14 centimetres to global sea-level rise, according to a new study published in Scientific Data.
The assessment, led by the Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE), combines 42 independent estimates from 27 satellite missions to produce one of the most comprehensive long-term assessments of changes in the two major ice sheets. The record extends back to 1972 for Greenland and 1979 for Antarctica.
Researchers found that 84 percent of the combined ice loss resulted from faster-flowing glaciers discharging more ice into the ocean, while 16 percent was linked to changes in surface mass balance, including snowfall and surface melting. Scientists say the findings point to the growing influence of warmer ocean waters on the dynamics of the ice sheets.
Ice loss accelerated sharply from the 1990s and increased substantially during the 2010s. Greenland lost about 6,215 billion tonnes of ice between 1972 and 2023, while Antarctica lost about 4,780 billion tonnes between 1979 and 2023. Together, the two ice sheets are now responsible for roughly a quarter of global sea-level rise.
The study found that Greenland contributed about 1.81 centimetres to global sea-level rise during the period from 1979 to 2023, while Antarctica contributed about 1.33 centimetres. The combined rise was about 31.4 millimetres.
The scale of the loss is illustrated by the amount of water added to the oceans. AP reported that the lost ice represents nearly 3 quadrillion gallons of water. The resulting sea-level rise, although measured in only a few centimetres, is enough to increase the number of people exposed to coastal flooding by millions. Researchers estimate that the rise associated with the ice-sheet losses puts about 6 million to 9 million additional people at risk of coastal flooding and erosion.
Greenland’s Jakobshavn Glacier, one of its fastest-moving glaciers, has at times been retreating at about 50 metres per day, highlighting the speed at which some parts of the ice sheet can change.
Researchers noted that ice loss temporarily slowed between 2020 and 2023, particularly because of increased snowfall in parts of East Antarctica and milder conditions in Greenland. They cautioned, however, that this short-term change does not represent a reversal of the longer-term trend.
The findings provide a longer and more consistent record of polar ice loss and are intended to improve estimates of future sea-level rise and the risks facing coastal communities. Scientists say continued satellite monitoring will be essential for tracking how the ice sheets respond to a warming climate.
