Antarctica Climate change glacier

Scientists probe ancient history of the East Antarctic Ice Sheet and find unsettling news about sea level rise

The eastern Antarctic Wilkes Basin ice sheet seems to have receded during a warming event about 400,000 years ago—such a loss could add an additional 13 feet to sea level rise in the future

Researchers have found evidence of ice loss from Wilkes Basin in eastern Antarctica during a climate warming event 400,000 years ago, which suggests that parts of the East Antarctic ice sheet could be lost to modern warming trends—ultimately resulting in an additional 13 feet of sea level rise.


Scientists believe that over the last few million years, Earth's climate has oscillated between cooler periods when ice sheets spread across the poles and warmer periods when those ice sheets partially melted and sea levels rose. Climate scientists study these warmer periods hoping to refine climate models and make better predictions about the future impacts of human-caused climate change.

While the ice sheets of Greenland and western Antarctica have long been identified as vulnerable to climate change and drivers of sea level rise, the status of the East Antarctic Ice Sheet, the largest freshwater reservoir in the world, has been more ambiguous, with some suggestion that it has been stable for millions of years and resisted past warming events.

However, in a Nature paper published today, a team of researchers present evidence that the ice sheet covering Wilkes Basin in East Antarctica receded roughly 435 miles during the Marine Isotopic Stage 11, a particularly long period of warming that occurred roughly 400,000 ago. During this time, the Earth's average temperature increased between one and two degrees Celsius, an increase comparable to modern climate change projections.

Sea level rise happens relatively slowly—the global average sea level has risen about nine inches over the past 140 years, according to the National Oceanic and Atmospheric Administration.

But the finding that the Wilkes Basin is less stable than originally thought substantially adds to the problem—experts estimate that over the coming centuries the combined ice sheets of Greenland, western Antarctica, and, now, the Wilkes Basin, could cause sea levels to rise by 42 feet.

"For a long time now, it's been very difficult to reconstruct…what's happened to ice sheets in response to warming events," Terrence Blackburn, assistant professor of Earth and planetary sciences at University of California, Santa Cruz and lead author on the new paper, told EHN. "As soon as those glaciers re-advance during that cold period, they would cover up and destroy all that evidence. But what we have found is that there is another…archive of how long the ice has been stable."

Blackburn's team used an analysis of uranium isotopes in mineral samples dated from different times in Wilkes Basin history to create a timeline of glacier advance and retreat. Water, which typically contains trace amounts of uranium, naturally becomes enriched with a specific isotope of uranium, uranium-234, because of interactions between the water and rocks.

If this water is in a free-flowing source, like a stream, the uranium isotope gets diluted and never builds up. However, the researchers found that water trapped under glaciers will build up high levels of the uranium isotope.

This water will refreeze at the edges of the glacier and its minerals will all precipitate out, forming opal and calcite deposits. The uranium-234 content of the glacier water is effectively recorded inside these deposits. By locating and dating the deposits, researchers can learn what the isotopic makeup of the subglacial water was at the time the deposit was formed.

The researchers found that during the Marine Isotopic Stage 11, uranium-234 enrichment levels dropped, and then began to slowly build back up.

The researchers believe the decline in uranium-234 enrichment occurred as glacial waters in the Wilkes Basin were flushed out by melting ice and sea water. But then, as temperatures cooled, the glacier began to reestablish itself and sequester enriched water in the Basin once again.

"People haven't really used this technique to infer retreat of the margins of the ice sheets before, so it's really cutting edge in that sense," Andrea Dutton, a paleoceanographer at University of Wisconsin-Madison and expert in sea level change who was not involved with the study, told EHN.

She added that, like areas of concern in western Antarctica, the Wilkes Basin ice sheet sits on ground that is below sea level. This structure makes glaciers more prone to melting as ocean water warms.

"Understanding how susceptible these vulnerable parts of the ice sheet, these marine base portions are is the biggest question right now in terms of providing accurate sea level projections for the future," said Dutton.

Robert Kopp, director of the Rutgers Institute of Earth, Ocean & Atmospheric Sciences who was not involved with the study, said that other areas of Antarctica, such as the Antarctic Peninsula and Thwaites Glacier, face a more near-term threat than Wilkes Basin, but that future melting in eastern Antarctica could be catalyzed by decisions that humanity makes today.

"What this is really about is…sea level commitment," he told EHN. "That is, if we warm the planet up two degrees, how much sea level rise do we expect to see over the coming many centuries to millennia as a result of that? What is the world we are creating for our descendants?"

Banner photo: The Matusevich Glacier flows toward the coast of East Antarctica. (Credit: NASA)

marshall fire pollution climate impacts
Photo by Mike Newbry on Unsplash

VOC levels in Marshall Fire area similar to ordinary urban air pollution, NOAA finds

NOAA used a mobile van to sample outdoor air in Louisville, Superior, and affected areas of unincorporated Boulder County 11 to 14 days after the Marshall Fire.

Sunrise in the woods

Get our Good News newsletter

Get the best positive, solutions-oriented stories we've seen on the intersection of our health and environment, FREE every Tuesday in your inbox. Subscribe here today. Keep the change tomorrow.

Can investors use European carbon allowances to force companies to curb pollution?

The worlds of high finance and climate change might appear to have nothing in common, but if they had a social media status, then it would probably be “it’s complicated”.

WSU study finds air pollution, brought on by heat and wildfires, is increasing in the West

The presence of harmful particles called particulate matter, or PM 2.5, and ozone can make air unhealthy to breathe, and a WSU researcher discovered that the frequency, intensity and unhealthy level of pollution from both particles has increased dramatically, especially in the past decade.

It's as bad as ever: Climate change denial still rages on social media

YouTube, Facebook, Twitter and TikTok have all made pledges to crack down on the spread of misinformation, but it’s still being promoted on all their platforms.

natural gas energy renewables
Photo by Andrew Charney on Unsplash

Natural gas a 'partner' in transition to renewables, says Crogga

Gas extracted from Manx waters could work alongside renewables to phase out coal, a local firm says.

How animals are adapting to climate change

Books by Thor Hanson and Emma Marris offer new insights into how species are surviving and what we must do to help.
coal mining cleanup
Photo by Albert Hyseni on Unsplash

PA to receive more than $3 billion to clean up abandoned coal mines

Pennsylvania will receive billions of dollars to clean up abandoned mines like the site Secretary Haaland visited in Swoyersville.
From our Newsroom
Africa cooking pollution

What do new cookstoves in Ghana and air conditioners in NYC have in common? Energy justice.

Combating energy poverty and energy insecurity are critical elements to achieving environmental health equity for billions worldwide.

dr. fauci

Peter Dykstra: Life imitates climate politics—again.

Personal, misinformed attacks on Dr. Fauci are reminiscent of climate spats over the decades.

Don't look up climate change

Hollywood’s third strike on climate change?

"Don't Look Up" is ambitious—but trips over its subject matter.

environmental news

5 popular reads from our newsroom in 2021

Check out what sparked readers' interest over the past year.

journalism

Our top 5 long reads of 2021

Check out must-read, in-depth reporting from the past year.

butterfly

Our top 5 good news stories of 2021

It's not all doom and gloom.

Stay informed: sign up for The Daily Climate newsletter
Top news on climate impacts, solutions, politics, drivers. Delivered to your inbox week days.