The world's glaciers are melting way faster than before, study says
Each year, enough ice is melting to cover Canada to a depth of 30 centimetres
A new study has used millions of satellite images to generate the clearest picture yet of the world's glaciers and concludes they're getting smaller, faster.
And glaciers along the western edge of North America are thinning faster than almost anywhere else in the world, said co-author Brian Menounos of the University of Northern British Columbia, whose paper was published Wednesday in the journal Nature.
"I don't think humans need more evidence the climate is changing," Menounos said.
"But I also think we can't throw up our hands and say, 'Oh, we can't do anything.' We have to understand the implications of climate change."
Scientists have long known that the world's 217,000 glaciers are in retreat.
That knowledge, however, was based on relatively infrequent satellite images and field monitoring that didn't include all glaciers. Menounos and his colleagues turned to a previously unused trove of images that allowed them to estimate the falling elevation of precise spots with unprecedented accuracy.
"We had (a supercomputer) running for a solid year of compute time," he said.
Once they knew how far the surface of the glaciers had fallen, they could calculate how much ice was lost. The results boggle the mind.
They found glaciers are now losing 267 billion tonnes of ice every year. Just one billion tonnes of ice — a gigatonne — is equal in mass to 10,000 fully loaded aircraft carriers.
Put another way, that's enough ice melting every year to cover Canada's entire land mass to a depth of 30 centimetres.
WATCH | Aerial views of the Klinaklini Glacier in 2019:
The pace is picking up. Between 2000 and 2004, when the study begins, glaciers "only" lost 227 gigatonnes per year.
Problem is worldwide, but worse in North America
But glaciers up the mountainous western spine of North America — including Canada — are melting even faster. Their thawing rate increased fourfold between 2000 and 2019.
Global glacier 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. Half the world's glacial loss is coming from the United States and Canada.
Alaska's melt rates are "among the highest on the planet," with the Columbia glacier retreating about 35 metres a year, Hugonnet said.
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Almost all the world's glaciers are melting, even ones in Tibet that used to be stable, the study found.
Except for a few in Iceland and Scandinavia that are fed by increased precipitation, the melt rates are accelerating around the world. The near-uniform melting "mirrors the global increase in temperature" and is from the burning of coal, oil and gas, Hugonnet said. Some smaller glaciers are disappearing entirely. Two years ago, scientists, activists and government officials in Iceland held a funeral for a small glacier.
Melting glaciers to blame for most sea level rise so far
Glaciers are now responsible for about 21 per cent of the roughly 22 centimetres that sea levels have risen since 1880.
That won't stop. By the end of the century, about 200 million people will live on land likely to be submerged at high tide.
"It's becoming increasingly clear that sea level rise is going to be a bigger and bigger problem as we move through the 21st century," said National Snow and Ice Data Center director Mark Serreze.
WATCH | Melting ice and glaciers could lead to water crisis:
Glaciers are also a crucial source of fresh water, as they are in Western Canada. The paper quotes research suggesting more than one billion people could face water shortages by 2050. That doesn't include other benefits humans rely on glaciers for. They keep headwaters streams cool, for example. "If you take that thermal buffering capacity of glaciers away, you're left with a situation where these aquatic ecosystems are going to change," Menounos said.
'Memorial of the climate crisis'
"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 wasn't part of the study.
Ohio State University's Lonnie Thompson said the new study painted an "alarming picture."
With a file from the Associated Press