Greenland and Antarctica have lost a combined 11,309 billion tonnes of ice between 1979 and 2023 contributing 31.4 millimetres to global sea level rise, according to a new international assessment by polar scientists.
The assessment, led by researchers at Northumbria University with support from NASA, brings together observations from 42 independent satellite surveys covering 27 satellite missions. Researchers used satellite records dating back to 1972 for Greenland and 1979 for Antarctica to examine changes in the two major ice sheets over several decades.
Greenland accounted for the larger share of the overall loss, while Antarctica contributed approximately 13.3 millimetres to global sea level rise during the study period.
Glaciers Responsible for Most Ice Loss
A key finding of the assessment is that most of the ice loss resulted from glaciers accelerating and releasing more ice into the ocean rather than from surface melting.
Researchers estimated that about 84% of the total ice loss occurred through increased glacier discharge, while surface melting accounted for around 16%.
Dr Ines Otosaka, one of the study’s leads, said the extended record has helped scientists better understand how the ice sheets have responded to a warming climate. The researchers linked the long term changes to the dynamic response of the ice sheets, including the influence of warming oceans.
Ice Loss Accelerated From the 1990s
The assessment found that annual ice losses increased substantially from the 1990s onward.
In Greenland, annual ice loss rose from about 60 billion tonnes in the 1980s to approximately 264 billion tonnes in the 2010s. The decade also saw several extreme summer melting events.
Antarctica annual ice loss increased from roughly 48 billion tonnes in the 1980s to around 202 billion tonnes in the 2010s.
Together, the Greenland and Antarctic ice sheets are estimated to account for about a quarter of global sea level rise. Recent Slowdown Does Not Mean Ice Loss Has Reversed
Researchers observed a temporary slowdown in ice loss between 2020 and 2023 but cautioned that the change does not indicate a reversal of the longer term trend.
In Antarctica, unusually high snowfall over parts of East Antarctica offset some of the ice lost through glacier discharge elsewhere on the continent. In Greenland, relatively mild summers reduced surface melting during the period.
Scientists described these changes as short term fluctuations within a much longer pattern of ice loss. The researchers highlighted the implications of continued ice sheet loss for coastal populations.
Professor Andrew Shepherd of Northumbria University said that even a few centimetres of additional sea level rise can increase exposure to coastal flooding and erosion, potentially affecting millions of people living in vulnerable areas.
The assessment also emphasised the importance of continued satellite monitoring. Researchers said longer observation records, a larger number of participating scientific teams and improved methods for assessing uncertainties have strengthened understanding of ice sheet mass changes.
Scientists say the multi-decade record provides important evidence of how Greenland and Antarctica are responding to a warming climate. Continued observations will be crucial for improving projections of future sea level rise and assessing risks to low lying coastal communities.