Study: Two-thirds of glaciers on track to disappear by 2100

The world’s glaciers are shrinking and disappearing faster than scientists thought, with two-thirds of them projected to melt out of existence by the end of the century at current climate change trends, according to a new study.

But if the world can limit future warming to just a few more tenths of a degree and fulfill international goals — technically possible but unlikely according to many scientists — then slightly less than half the globe’s glaciers will disappear, said the same study. Mostly small but well-known glaciers are marching to extinction, study authors said.

In an also unlikely worst-case scenario of several degrees of warming, 83% of the world’s glaciers would likely disappear by the year 2100, study authors said.

<p>Chunks of ice float on Mendenhall Lake in front of the Mendenhall Glacier on May 30, 2022, in Juneau, Alaska.</p>

Becky Bohrer, AP file photo

Chunks of ice float on Mendenhall Lake in front of the Mendenhall Glacier on May 30, 2022, in Juneau, Alaska.

The study in Thursday’s journal Science examined all of the globe’s 215,000 land-based glaciers — not counting those on ice sheets in Greenland and Antarctica — in a more comprehensive way than past studies. Scientists then used computer simulations to calculate, using different levels of warming, how many glaciers would disappear, how many trillions of tons of ice would melt, and how much it would contribute to sea level rise.

The world is now on track for a 4.9 degrees Fahrenheit temperature rise since pre-industrial times, which by the year 2100 means losing 32% of the world’s glacier mass, or 48.5 trillion metric tons of ice as well as 68% of the glaciers disappearing. That would increase sea level rise by 4.5 inches in addition to seas already getting larger from melting ice sheets and warmer water, said study lead author David Rounce.

“No matter what, we’re going to lose a lot of the glaciers,” Rounce, a glaciologist and engineering professor at Carnegie Mellon University, said. “But we have the ability to make a difference by limiting how many glaciers we lose.”

“For many small glaciers it is too late,” said study co-author Regine Hock, a glaciologist at the University of Alaska Fairbanks and the University of Oslo in Norway. “However, globally our results clearly show that every degree of global temperature matters to keep as much ice as possible locked up in the glaciers.”

Projected ice loss by 2100 ranges from 38.7 trillion metric tons to 64.4 trillion tons, depending on how much the globe warms and how much coal, oil and gas is burned, according to the study.

The study calculates that all that melting ice will add anywhere from 3.5 inches in the best case to 6.5 inches in the worst case to the world’s sea level, 4% to 14% more than previous projections.

That 4.5 inches of sea level rise from glaciers would mean more than 10 million people around the world — and more than 100,000 people in the United States — would be living below the high tide line, who otherwise would be above it, said sea level rise researcher Ben Strauss, CEO of Climate Central. Twentieth-century sea level rise from climate change added about 4 inches to the surge from 2012 Superstorm Sandy costing about $8 billion in damage just in itself, he said.

<p>This combination of Sept. 14, 1986, left, and Aug. 1, 2019, photos provided by NASA shows the shrinking of the Okjokull glacier on the Ok volcano in west-central Iceland. A geological map from 1901 estimated Okjökull spanned an area of about 38 square kilometers (15 square miles). In 1978, aerial photography showed the glacier was 3 square kilometers. in 2019, less than 1 square kilometer remained.</p>

NASA, via AP

This combination of Sept. 14, 1986, left, and Aug. 1, 2019, photos provided by NASA shows the shrinking of the Okjokull glacier on the Ok volcano in west-central Iceland. A geological map from 1901 estimated Okjökull spanned an area of about 38 square kilometers (15 square miles). In 1978, aerial photography showed the glacier was 3 square kilometers. in 2019, less than 1 square kilometer remained.

Scientists say future sea level rise will be driven more by melting ice sheets than glaciers.

But the loss of glaciers is about more than rising seas. It means shrinking water supplies for a big chunk of the world’s population, more risk from flood events from melting glaciers and about losing historic ice-covered spots from Alaska to the Alps to even near Mount Everest’s base camp, several scientists told The Associated Press.

“For places like the Alps or Iceland … glaciers are part of what makes these landscapes so special,” said National Snow and Ice Data Center Director Mark Serreze, who wasn’t part of the study but praised it. “As they lose their ice in a sense they also lose their soul.”

Hock pointed to Vernagtferner glacier in the Austrian Alps, which is one of the best-studied glaciers in the world, but said “the glacier will be gone.”

<p>People climb to the top of what once was the Okjokull glacier on Aug. 18, 2019, in Iceland. With poetry, moments of silence and political speeches about the urgent need to fight climate change, Icelandic officials, activists and others bade goodbye to the first Icelandic glacier to disappear.</p>

Felipe Dana, AP file photo

People climb to the top of what once was the Okjokull glacier on Aug. 18, 2019, in Iceland. With poetry, moments of silence and political speeches about the urgent need to fight climate change, Icelandic officials, activists and others bade goodbye to the first Icelandic glacier to disappear.

The Columbia Glacier in Alaska had 216 billion tons of ice in 2015, but with just a few more tenths of a degree of warming, Rounce calculated it will be half that size. If there’s 7.2 degrees Fahrenheit of warming since pre-industrial times, an unlikely worst-case scenario, it will lose two-thirds of its mass, he said.

“It’s definitely a hard one to look at and not drop your jaw at,” Rounce said.

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