Quantcast
Environmental News for a Healthier Planet and Life

Alaska's Rapidly Melting Glaciers: A Major Driver of Global Sea Level Rise

Climate
Alaska's Rapidly Melting Glaciers: A Major Driver of Global Sea Level Rise

The glaciers of Alaska are melting and retreating: the chief cause is climate change and the loss of ice is unlikely to slow, according to a new study by U.S. scientists.

Alaska’s Columbia Glacier is almost 20 kilometers shorter than it was in 1980. Photo credit: U.S. Fish and Wildlife Service / Wikimedia Commons

They calculate that the frozen rivers of the Pacific coast of America’s northernmost state are melting fast enough to cover the whole of Alaska with 30 centimeters of water every seven years.

Since Alaska is enormous—it covers 1.5 million square kilometers and is the size of California, Texas and Montana put together—this adds up to a significant contribution to sea level rise.

“The Alaska region has long been considered a primary player in the global sea level budget, but the exact details of the drivers and mechanisms of Alaska glacier change have been stubbornly elusive,” said Chris Larsen, a geophysicist at the University of Alaska Fairbanks, and lead author of a study in Geophysical Research Letters.

Taxonomy of change

Scientists from the University of Alaska and the U.S. Geological Survey analyzed studies of 116 glaciers in the Alaska region over a 19-year-period to estimate the rate at which ice melted and icebergs calved.

They used airborne lidar remote sensing technology and other techniques, historical data and a global glacier inventory to establish a kind of taxonomy of glacier change.

The Columbia Glacier in Prince William Sound had retreated more than 19 kilometers because of iceberg calving and had thinned by 450 meters in height since 1980. But, unexpectedly, tidewater glaciers—those that end in the ocean—seemed to make comparatively little contribution to sea level rise.

“Instead we show that glaciers ending on land are losing mass exceptionally fast, overshadowing mass changes due to iceberg calving, and making climate-related melting the primary control on mountain glacier mass loss,” Larsen said.

Big contributor

He and his colleagues calculated that Alaska is losing ice at the rate of 75 billion metric tons a year. Such research is just one more piece of careful cross-checking in the great mosaic of climate research: another systematic confirmation that overall, glaciers are not losing ice in response to some natural cycle of change of the kind that occasionally confuses the picture for climate science.

The agency at work is largely global warming as a response to the steady rise in atmospheric carbon dioxide as a consequence of the burning of fossil fuels.

Mountain glaciers represent only one percent of the total ice on the planet: the other 99 percent is found in Greenland—which is melting fast—and in the great frozen continent of Antarctica, where ice mass is being lost at an increasing rate.

But although the mountains of the temperate and tropic zones bear only a tiny percentage of the planet’s ice, their melting accounts for almost a third of the sea level rise currently measured by oceanographers, and this melting will go on to become a big contributor to the sea levels later this century.

Across the border in Canada, glaciologists have warned that the country will lose a huge volume of flowing ice, and while one team has confirmed that air pollution rather than global warming long ago began to strip Europe’s Alps of their glaciers, in general mountain peaks are warming faster than the valleys and plains below them.

Geophysicists and glaciologists have established that the glaciers of the tropical Andes are at risk, and in the Himalayan mountain chain glaciers seem to be in inexorable retreat with consequences that could be devastating for the many millions in the Indian subcontinent and in China who rely on seasonal meltwater for agriculture.

Glaciers are by definition hard to study—they are high, cold and in dangerous terrain—and such research is inevitably incomplete: the scientists, for instance, excluded glaciers smaller than three square kilometers. But together these small patches of flowing ice account for 16 percent of Alaska’s glaciated landscape. The 116 glaciers in the survey together added up to only 41 percent of the state’s glaciated area.

But the pattern established by the Fairbanks team suggests that melting will accelerate with climate change. “Rates of loss from Alaska are unlikely to decline, since surface melt is the predominant driver, and summer temperatures are expected to increase,” said Dr Larsen.

“There is a lot of momentum in the system, and Alaska will continue to be a major driver of sea level change in the upcoming decades.”

YOU MIGHT ALSO LIKE

10 Coastal Destinations Most at Risk From Sea Level Rise

Is Antarctica Ice Melting or Growing? Watch This NASA Video and See for Yourself

10 Iconic Places That May Disappear Due to Climate Change

Valley of the Gods in the heart of Bears Ears National Monument. Mint Images / Getty Images

By Sharon Buccino

This week, Secretary Haaland chose a visit to Bears Ears National Monument as her first trip as Interior Secretary. She is spending three days in Bluff, Utah, a small town just outside the monument, listening to representatives of the five tribes who first proposed its designation to President Obama in 2015. This is the same town where former Secretary Sally Jewell spent several hours at a public hearing in July 2016 before recommending the monument's designation to President Obama.

Read More Show Less
EcoWatch Daily Newsletter
Pexels

By Anthony Richardson, Chhaya Chaudhary, David Schoeman, and Mark John Costello

The tropical water at the equator is renowned for having the richest diversity of marine life on Earth, with vibrant coral reefs and large aggregations of tunas, sea turtles, manta rays and whale sharks. The number of marine species naturally tapers off as you head towards the poles.

Read More Show Less
Trending
"Secrets of the Whales" is a new series that will start streaming on Disney+ on Earth Day. Disney+

In celebration of Earth Day, a star-studded cast is giving fans a rare glimpse into the secret lives of some of the planet's most majestic animals: whales. In "Secrets of the Whales," a four-part documentary series by renowned National Geographic Photographer and Explorer Brian Skerry and Executive Producer James Cameron, viewers plunge deep into the lives and worlds of five different whale species.

Read More Show Less
Spring is an excellent time to begin bird watching in earnest. Eugenio Marongiu / Cultura / Getty Images

The coronavirus has isolated many of us in our homes this year. We've been forced to slow down a little, maybe looking out our windows, becoming more in tune with the rhythms of our yards. Perhaps we've begun to notice more, like the birds hopping around in the bushes out back, wondering (maybe for the first time) what they are.

Read More Show Less
The brown pelican is seen on Queen Bess Island in Louisiana in March 2021. Casey Wright / LDWF biologist

Who says you can't go home again?

Read More Show Less