Glaciers are melting faster, losing 31% more snow and ice per year than 15 years earlier, according to three-dimensional satellite measurements of all the world’s mountain glaciers.
Scientists blame human-caused climate change.
Using 20 years of recently declassified satellite data, scientists calculated that the world’s 220,000 mountain glaciers are losing more than 328 billion tons (298 billion metric tons) of ice and snow per year since 2015, according to a published study. Wednesday at the Nature magazine . That’s enough melt flowing into the world’s rising oceans to put Switzerland under almost 24 feet (7.2 meters) of water every year.
The annual melt rate from 2015 to 2019 is 78 billion more tons (71 billion metric tons) per year than from 2000 to 2004. Global rates of thinning, other than the volume of water lost, doubled in the past 20 years and “that’s huge,” said Romain Hugonnet, a glaciologist at ETH Zurich and the University of Toulouse in France who led the study.
Half of the world’s glacier loss comes from the United States and Canada.
Alaska’s melt rates are “Among the highest on the planet”, and the Columbia Glacier retreats about 115 feet (35 meters) a year, Hugonnet said.
Almost all of the world’s glaciers are melting, even those in Tibet that used to be stable, the study found. Except for a few in Iceland and Scandinavia that are fueled by increased rainfall, melt rates are accelerating around the world.
Almost uniform fusion “Reflects the global increase in temperature” and it is due to burning coal, oil and gas Hugonnet said. Some smaller glaciers are completely disappearing. Two years ago, Icelandic scientists, activists and government officials they held a funeral by a small glacier.
“Ten years ago, we said that glaciers are the indicator of climate change, but now they have actually become a memorial of the climate crisis”said the director of the World Glacier Monitoring Service, Michael Zemp, who was not part of the study. .
The study is the first to use these 3D satellite images to examine all of the glaciers on Earth that are not connected to the ice sheets in Greenland and Antarctica. Previous studies only used one fraction of glaciers or estimated the loss of Earth’s glaciers using gravity measurements from orbit. Those gravity readings have large margins of error and aren’t that helpful, Zemp said.
Lonnie Thompson of Ohio State University said the new study presented an “alarming picture.”
Shrinking glaciers are a problem for millions of people who depend on seasonal glacier melt for daily water, and rapid melting can cause deadly explosions of glacial lakes in places like India, Hugonnet said.
But the biggest threat is rising sea levels. The world’s oceans are already increasing because the warm water expands and due to the melting of the ice sheets in Greenland and Antarctica, but glaciers are responsible for 21% of the rise in sea level, more than the ice sheets, according to the study. Ice sheets are major long-term threats to sea level rise.
“It is becoming increasingly clear that rising sea levels will be a growing problem as we move into the 21st century,” said Mark Serreze, director of the National Ice and Snow Data Center.