Nearly all of the world’s glaciers are losing mass – and at an accelerated pace, according to a new study that experts said painted an “alarming picture”.
The research published on Wednesday in the science journal Nature provides one of the most wide-ranging overviews yet of ice mass loss from about 220,000 glaciers around the world, a major source of sea-level rise.
Using high-resolution imagery from NASA’s Terra satellite from 2000-2019, a group of international scientists found that glaciers, with the exception of the Greenland and Antarctic ice sheets which were excluded from the study, lost an average of 267 gigatonnes of ice per year.
A gigatonne of ice would fill New York City’s Central Park and stand 341 metres (1,119 feet) high.
The researchers also found that glacier mass loss accelerated. Glaciers lost 227 gigatonnes of ice annually from 2000 to 2004, but that increased to an average of 298 gigatonnes each year after 2015.
The melt was significantly impacting sea levels by about 0.74 millimetres a year, or 21 percent of overall sea-level rise observed during the period.
Glaciers tend to have a faster response to climate change compared with ice sheets in Greenland and Antarctica, and are currently contributing more to sea-level rise than either individual ice sheet, scientists said.
The study could fill important gaps in understanding ice mass loss, leading to more accurate predictions, said co-author of the study Robert McNabb, a remote sensing scientist at Ulster University in the United Kingdom. Previous studies looking at individual glaciers only account for about 10 percent of the planet, he said.
Scientists have long warned that warming temperatures driven by climate change are eating into glaciers and ice sheets around the world, contributing to higher sea levels that threaten the world’s populous coastal cities.
Global thinning rates, different than volume of water lost, doubled in the last 20 years and “that’s enormous,” said Romain Hugonnet, a glaciologist at ETH Zurich and the University of Toulouse in France who led the study.
Shrinking glaciers are a problem for millions of people who rely on seasonal glacial melt for daily water and rapid melting can cause deadly outbursts from glacial lakes in places like India, added Hugonnet.
“Ten years ago, we were saying that the glaciers are the indicator of climate change, but now actually they’ve become a memorial of the climate crisis,” said World Glacier Monitoring Service Director Michael Zemp, who was not part of the study.