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Alaska's Glaciers Shrinking at Record Rate

作者:Alice Bryant 发布日期:12-16-2019

The year 2019 will soon be the hottest on record for the American state of Alaska.

Its glaciers are melting at record or near-record levels, pouring waters into rising seas, scientists say. The Reuters news agency spoke with the scientists after they made measurements around Alaska this autumn.

Record levels of ice and snow are disappearing from the Lemon Creek Glacier in Juneau, the state capital. The Lemon Creek Glacier had its second year of record mass loss, with three meters gone from the surface. That information comes from Louis Sass, a glaciologist with the United States Geological Survey, or USGS. Juneau's glacial records date back to the 1940s.

Melt went all the way up to the top, said Sass. "That's a really bad sign for a glacier," he said, noting that melting ice very high up means there is no buildup of snow to make new ice and help balance ice loss in lower areas.

Former President Barack Obama looks at Bear Glacier while on a boat tour seeing the effects of climate change in Resurrection Cove, Tuesday, Sept. 1, 2015, in Seward, Alaska.
Former President Barack Obama looks at Bear Glacier while on a boat tour seeing the effects of climate change in Resurrection Cove, Tuesday, Sept. 1, 2015, in Seward, Alaska.

At Wolverine Glacier i n the Kenai Peninsula, south of the city of Anchorage, loss was the second highest in a record that goes back to the 1960s. Sass said it failed to reach the record set in 2004 – but only because so much of the glacier had already melted.

"The lower part's completely gone now," he noted.

Extreme melting was also reported at Kenai Fjords National Park, which former President Barack Obama once visited to call attention to climate change. There, Bear Glacier had shrunk by close to a kilometer in just 11 months, the National Park Service noted, based on August measurements. Bear Glacier is a popular stop for vacationers.

"It's almost like you popped it and it started to deflate," said Nate Lewis. He is a wilderness guide who takes travelers out on the new lake that has formed at the bottom of the shrinking glacier.

Even one of the few Alaska glaciers that had been expanding, Taku, is now quickly losing ice. Taku is southeast of Juneau.

Especially worrisome is the high altitude at which Taku is melting, said Mauri Pelto, who heads the North Cascades Glacier Climate Project.

In 2019, the summer melt reached as high as 1,450 meters, 25 meters above the earlier high-altitude record set just last year, he said.

Losing large pieces

Now that it is shrinking, Taku is expected to start losing big ice pieces, increasing Alaska's effect on rising sea levels, says a report by the U.S. Geological Survey's Chris McNeil. Louis Sass, Shad O'Neel and other glaciologists with the USGS helped McNeil write the report.

The findings are to be presented at a meeting of the American Geophysics Union later this month in San Francisco.

Alaska recorded its warmest month ever in July and the warmer weather has continued.

Brian Brettschneider is a climatologist with the University of Alaska Fairbanks' International Arctic Research Center. Recently on Twitter, he wrote that Alaska will break the record for the warmest year unless December gets colder than expected.

Alaska's glaciers make up far less than one percent of the world's land ice. But their melt makes up about seven percent of the water that is raising the world's sea levels. That information is from a 2018 study published in the journal Geophysical Research Letters.

There are also local effects. Scientists say glacial melt affects not only waters where salmon reproduce, but the natural habitats of other creatures. It is creating new lakes in places where ice used to be and outburst floods from those lakes are happening more often, scientists say.

An outburst flood is a sudden release of water from a dam created by glacial melt. These floods result when part of the dam fails.

Changes in the glaciers and the ecosystems they feed has happened so fast that they are hard to follow, said O'Neel of USGS.

I'm Alice Bryant.

Yereth Rosen reported this story for Reuters News Agency. Alice Bryant adapted the story for Learning English. George Grow was the editor.

Words in This Story

glaciern. a very large area of ice that moves slowly down a slope or valley or over a wide area of land

peninsula n. a piece of land that is almost entirely surrounded by water and is attached to a larger land area

deflate v. to release air or gas from something, such as a tire or balloon, and make it smaller

altitude n. the height of something above the level of the sea

habitat n. the place or type of place where a plant or animal naturally or normally lives or grows

ecosystem n. a biological community of interacting organisms and their physical environment

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