Using high-resolution imagery from Nasa's Terra satellite from between 2000 and 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 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 per cent 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 that either individual ice sheet, scientists said.

The study could fill important gaps in understanding about 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 per cent of the planet, he said.
Some glaciers in Alaska, Iceland, the Alps, the Pamir mountains and the Himalayas were among the most impacted by melting, researchers found. Glaciers with surrounding communities provide an important water source and their decline could lead to serious food and water shortages.

"Those areas are seeing a rapid pace of glacier melt that could be fairly worrying," McNabb said.

"We get this increase in melt and that actually increases the availability of water that comes in these rivers... but the problem is, after a period of time, that stops increasing and then decreases fairly rapidly," he added.
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