Nearly all the world's glaciers are accelerating and at a loss of mass, according to a new study published Wednesday that could impact future projections for ice loss.
The study in the science journal Nature provides one of the most major overviews yet of the ice loss from about 220,000 glaciers in the world, a wide source of sea level rise.
Using international imagery from NASA's Terra satellite from 2000 to 2019, a group of high scientists found that glaciers lost an average of 267 gigatonnes of ice per year, with the exception of the Greenland and Antarctic ice sheets excluded in the study.
A gigatonne of ice would fill New York City's Central Park and be 341 meters high.
The researchers also found that glacier mass loss accelerated.From 2000 to 2004, glaciers lost 227 gigatonnes of ice annually but that grew to an average of 298 gigatonnes each year after 2015.
The melt was observed significantly affecting sea levels by roughly 0.74 millimetres a year, or 21% of the sea level rise observed during this period.
Glaciers tend to have a faster response to climate change compared to individual ice sheets in Greenland and Antarctica and are currently contributing more to sea level rise than either individual ice sheet, the scientists said.
The study could fill important gaps in understanding of ice mass loss, leading to better predictions, said co-author of the study Robert McNabb, a remote sensing scientist at Ulster University in the United Kingdom.Previous studies into individual glaciers only account for about 10% of the planet, he said.
Scientists have long warned that warming temperatures driven by climate change are attacking glaciers and ice sheets around the world, contributing to higher sea levels that threaten the planet's populous coastal cities.The latest reports by the Intergovernmental Panel on Climate Change Project project that future sea levels will increase by 2100 by more than a meter.
Some glaciers were found in Alaska, Iceland, the Alps, the Pamir mountains and the Himalayas to be among the most impacted by meltingGlaciers with surrounding communities provide an important water source and their decline could lead to serious food and water shortages.
These areas are seeing a speed of glacier melt that could be pretty worrying, McNabb said.
We get this increase in the melt and that really increases the availability of water that comes in these rivers, but the problem is, after a period of time, that decreases pretty soon and increases somewhat quickly, he added.
While the study did not dive into the cause of the human retreat, rising temperatures widely believed by scientists to be the result of glacial emissions inevitably led to more ice loss, McNabb said.
It's hard to separate the fact that temperature is what causes melting with the fact that humans are, by and large, causing the increase in temperature, he said.
Once glacial ice has melting it may take decades or centuries to regrow because it must pile up year after year, scientists said.The study reiterates that the world must slow global temperatures to reduce ice loss, said Twila Moon, a glaciologist at the National Snow and Ice Data Center who was not involved in the study.
I have no expectation, in all honesty, that even substantial action to reduce the earth's emissions and control the Earth's temperature increase is going to grow our glaciers, Moon said.We are at a point where we're trying to keep as much ice as possible and slow this loss rate, she added.
While researchers identified instances where melting rates actually slow down on the east coast of Greenland between 2000 and 2019, they attribute this to a weather anomaly that led to more precipitation and lower temperatures.
McNabb said the overall image of the study was one of fairly quick ice mass loss, with no indication it would change soon but there is still time to put brakes on melt by reducing emissions.
When you see something like this in which glaciers are losing mass it's getting faster, that really sounds bad, he said.But there is something that we need to act on.