Over the last fifty years, Greenland and Antarctica have lost 11.3 trillion tonnes of ice

The longest series of satellite observations ever produced shows that since the 1970s Greenland and Antarctica have lost 11.3 trillion tonnes of ice, a phenomenon that has raised the global average sea level by more than three centimetres. Most of this ice loss is not due to surface melting, but to glaciers flowing more rapidly towards the ocean.

Published in the journal Scientific Data, the analysis was carried out by an international team of scientists from the IMBIE (Ice Sheet Mass Balance Inter-comparison Exercise) group, coordinated by scholars from Northumbria University and the University of Washington, and supported by ESA and NASA.

The study combined 42 independent satellite measurements, based on 27 missions from 1972 for Greenland and from 1979 for Antarctica. Data analysis shows that between 1979 and 2023 the two ice sheets lost 11,309 billion tonnes of ice, increasing the global average sea level by 31.4 millimetres.

Greenland lost the largest share of ice, accounting for an 18.1 millimetre rise in sea level, while Antarctica contributed 13.3 millimetres. Scientists point out that 84% of the overall loss was caused by the acceleration of glaciers and the resulting greater discharge of ice into the ocean, while only 16% is due to surface melting.

"These results underscore the central role of ice sheets in future sea level rise", says Giorgio Spada, Professor at the Department of Physics and Astronomy - DIFA "Augusto Righi" of the University of Bologna, who took part in the study. "Their response to climate warming is the main source of uncertainty in projections, and a continuous half-century record of ice-sheet behaviour is therefore essential to predict the risks threatening the hundreds of millions of people living in low-lying coastal areas".

The historical series shows that ice losses have increased rapidly since the 1990s. Greenland, close to balance in the 1970s, saw its rate of loss rise from around 60 billion tonnes per year in the 1980s to 264 billion in the 2010s, a decade marked by repeated extreme summer melt events. Antarctica’s loss rate, meanwhile, rose from around 48 billion tonnes per year in the 1980s to 202 billion in the 2010s.

The most recent years (2020–2023) recorded a temporary slowdown in ice loss. Record snowfall over East Antarctica offset part of the glacial losses occurring elsewhere on the continent, while a series of milder summers in Greenland roughly halved surface melting. Scientists warn, however, that these are short-term oscillations against the backdrop of a clear long-term trend, not a reversal of ice loss.

The study was published in the journal Scientific Data under the title “Mass balance of the Greenland and Antarctic ice sheets from the 1970s to 2023”. For the University of Bologna, the study involved Giorgio Spada, a Professor at the Department of Physics and Astronomy - DIFA "Augusto Righi".