Quantcast

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

Climate

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

Show Comments ()

EcoWatch Daily Newsletter

PhotoAlto / Laurence Mouton / Getty Images

By Ana Reisdorf, MS, RD

You've probably heard the buzz around collagen supplements and your skin by now. But is the hype really that promising? After all, research has pointed to both the benefits and downsides of collagen supplements — and for many beauty-conscious folk, collagen isn't vegan.

Read More Show Less
Pixabay

By Marlene Cimons

Neil Pederson's introduction to tree rings came from a "sweet and kindly" college instructor, who nevertheless was "one of the most boring professors I'd ever experienced," Pederson said. "I swore tree rings off then and there." But they kept coming back to haunt him.

Read More Show Less
Sponsored
Aerial view of the explosion site of a chemical factory on March 22 in Yancheng, Jiangsu Province of China. Caixin Media / VCG / Getty Images)

At least 47 people have died in an explosion at a plant in Yancheng, China Thursday run by a chemical company with a history of environmental violations, Sky News reported.

Read More Show Less
A fishmonger in Elmina, a fishing port in the Central Region of Ghana. Environmental Justice Foundation

By Daisy Brickhill

Each morning, men living in fishing communities along Ghana's coastline push off in search of the day's catch. But when the boats come back to shore, it's the women who take over.

Read More Show Less
Pexels

By Sam Nickerson

Links between excess sugar in your diet and disease have been well-documented, but new research by Harvard's School of Public Health might make you even more wary of that next soda: it could increase your risk of an early death.

The study, published this week in the American Heart Association's journal Circulation, found that drinking one or two sugar-sweetened beverages (SSBs) each day — like sodas or sports drinks — increases risk of an early death by 14 percent.

Read More Show Less
Sponsored
Krystal B / Flickr

Tyson Foods is recalling approximately 69,093 pounds of frozen chicken strips because they may have been contaminated with pieces of metal, the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) announced Thursday.

The affected products were fully-cooked "Buffalo Style" and "Crispy" chicken strips with a "use by" date of Nov. 30, 2019 and an establishment number of "P-7221" on the back of the package.

"FSIS is concerned that some product may be in consumers' freezers," the recall notice said. "Consumers who have purchased these products are urged not to consume them. These products should be thrown away or returned to the place of purchase."

Read More Show Less
Pixabay

By Hrefna Palsdottir, MS

Cold cereals are an easy, convenient food.

Read More Show Less
A tractor spraying a field with pesticides in Orem, Utah. Aqua Mechanical / CC BY 2.0

Environmental exposure to pesticides, both before birth and during the first year of life, has been linked to an increased risk of developing autism spectrum disorder, according to the largest epidemiological study to date on the connection.

The study, published Wednesday in BMJ, found that pregnant women who lived within 2,000 meters (approximately 1.2 miles) of a highly-sprayed agricultural area in California had children who were 10 to 16 percent more likely to develop autism and 30 percent more likely to develop severe autism that impacted their intellectual ability. If the children were exposed to pesticides during their first year of life, the risk they would develop autism went up to 50 percent.

Read More Show Less