A “crater” in Antarctica once thought to be the work of a meteorite impact is actually the result of ice melt, new research finds.

The hole, which is in the Roi Baudouin ice shelf in East Antarctica, is a collapsed lake — a cavity formed when a lake of meltwater drained — with a “moulin,” a nearly vertical drainage passage through the ice, beneath it, researchers found on a field trip to the area in January 2016.


“That was a huge surprise,” Stef Lhermitte, an earth science researcher at Delft University of Technology in the Netherlands and at the University of Leuven in Belgium, said in a statement. “Moulins typically are observed on Greenland. And we definitely never see them on an ice shelf.”

– Surprising melt –

Combining their fieldwork with satellite data and climate modeling, the researchers found that East Antarctica is more vulnerable to melt than was previously realized. Warm winds to the region blow away the snow cover, which darkens the surface of the ice, the team reported Dec. 12 in the journal Nature Climate Change. Darker surfaces absorb more heat from the sun than lighter surfaces, so they are more prone to melt. These floating ice sheets don’t contribute much to sea level rise ­— as they’re already in the ocean — but they provide an important backstop against the flowing of land-based ice from continental Antarctica into the ocean.

East Antarctica has been a mysterious place when it comes to climate change. The region has been gaining ice due to increases in snow accumulation, according to 2015 research. Global warming can increase snowfall by boosting the amount of moisture in the air (warm air holds more moisture than cold).

The Roi Baudouin crater was more mysterious still. It’s existed on satellite images going back to at least 1989, researchers said, but was first noted widely in January 2015. Scientists initially reported it to be a meteorite crater, perhaps the result of a space rock that exploded over Antarctica in 2004. But scientists quickly questioned whether the 2-mile-wide circle was really from a meteorite. Many suspected it was the result of melting ice.

Jan Lenaerts, a climate researcher at Utrecht University in the Netherlands and at the University of Leuven, was one of the meteorite skeptics.

“My response was: ‘In that area? Then it’s definitely not a meteorite; it’s proof of strong melting,'” he said in a statement.

– Vulnerable ice –

The new study confirms that hunch. During their fieldwork on the southernmost continent, researchers also discovered many other meltwater lakes beneath the surface of the Roi Baudouin ice sheet.

“The amount of meltwater differs immensely from year to year, but it clearly increases during warm years,” Lhermitte said.

Earlier research had shown that West Antarctica is very sensitive to climate change, Lenaerts said in the statement.

“Our research now suggests that the much larger East Antarctica ice sheet is also very vulnerable,” Lenaerts said.

Antarctica Photos: Meltwater Lake Hidden Beneath the Ice

Weather Station
Credit: Jan Lenaerts
The expanse of the Roi Baudouin ice shelf stretches out beyond a new weather station deployed by researchers doing fieldwork in the area. East Antarctica is a question mark with regard to climate change, with little known about the ice sheet’s vulnerability to global warming.
Melting Moulin
Credit: Stef Lhermitte
A view into the mouth of a moulin, or drainage passage through the Roi Baudouin ice sheet. Researchers were surprised to find such a feature in East Antarctica, because they’re not typically seen on ice sheets and are more well-known from Greenland in the Arctic.
Lake under ice
Credit: Stef Lhermitte
A meltwater lake under ice on the Roi Baudouin ice sheet in East Antarctica. Researchers found many of these lakes, some kilometers across, dotting the underside of the ice sheet. This one is about 13 feet (4 meters) below the surface.
Meltwater Stream
Credit: Sanne Bosteels
A meltwater stream flows along the Roi Baudouin ice sheet in East Antarctica. New research published in Nature Climate Change finds that East Antarctica is more vulnerable to warming than previously expected because of warm winds that blow away the snow cover on the ice.
Meltwater Stream
Credit: Sanne Bosteels
A meltwater stream on the Roi Baudouin ice sheet. Warm winds here blow away the snow cover and darken the surface of the ice, which in turn makes the ice sheet more vulnerable as it absorbs more heat from the sun.
Icy Camp
Credit: Sanne Bosteels
Field camp on the Roi Baudouin ice sheet during a scientific expedition to better understand the dynamics of East Antarctica’s melt.
Melt and Ice
Credit: Sanne Bosteels
A meltwater stream on the Roi Baudouin ice sheet. Using observations taken from this expedition combined with satellite data and climate modeling, scientists found that East Antarctica is more prone to melt than previously believed. The melting of the floating ice sheet doesn’t cause much ocean-level rise directly, but as ice sheets melt they allow land-based ice to flow more rapidly toward the sea.
Icy Landmarks
Credit: Sanne Bosteels
Two ice blocks inside a mysterious crater first observed on satellite imagery in 1989. The feature was first widely reported in 2015 as a possible meteorite impact zone, but climate scientists immediately suspected it might actually be a sign of melt. The crater turned out to be a collapsed lake and moulin.
Credit: Sanne Bosteels
A moulin in the Roi Baudouin ice sheet. These drainage passages allow meltwater to flow through the ice and into the ocean, but are known from Greenland. Researchers were surprised to find one on an Antarctic ice sheet.
Flowing Melt
Credit: Sanne Bosteels
Meltwater drains through the moulin in the King Baudouin ice sheet in East Antarctica. This feature as well as numerous under-ice lakes suggest that the region is vulnerable to the effects of a warming climate.
Exploring the moulin
Credit: Stef Lhermitte
Researchers on snowmobiles explore the crater in the Roi Baudouin ice sheet, pausing next to a moulin through which meltwater drains. West Antarctica was already known to be vulnerable to climate change; the new study published in Nature Climate Change suggests that East Antarctica is at risk too.
Beauty at the bottom of the world
Credit: Sanne Bosteels
The edge of the Roi Baudouin ice sheet with floating sea ice alongside it. This area has shown little overt sign of ice loss, and in fact has seen some ice gain as snow accumulation has increased. But that snow accumulation may be a result of climate change, as warm air holds more moisture than cold air. Now, signs of hidden melt below the ice suggest that the region is vulnerable.


Antarctica is Earth’s southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean.

This map uses an orthographic projection, near-polar aspect. The South Pole is near the center, where longitudinal lines converge.

At 14,000,000 square kilometres (5,400,000 square miles), it is the fifth-largest continent. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 km (1.2 mi; 6,200 ft) in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.

Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is a desert, with annual precipitation of only 200 mm (8 in) along the coast and far less inland.

The temperature in Antarctica has reached −89.2 °C (−128.6 °F), though the average for the third quarter (the coldest part of the year) is −63 °C (−81 °F). Anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent.

Organisms native to Antarctica include many types of algae, bacteria, fungi, plants, protista, and certain animals, such as mites, nematodes, penguins, seals and tardigrades. Vegetation, where it occurs, is tundra.

Although myths and speculation about a Terra Australis (“Southern Land”) date back to antiquity, Antarctica is noted as the last region on Earth in recorded history to be discovered and/or colonized by humans, being only first sighted in 1820 by the Russian expedition of Fabian Gottlieb von Bellingshausen and Mikhail Lazarev on Vostok and Mirny, who sighted the Fimbul ice shelf.

The continent, however, remained largely neglected for the rest of the 19th century because of its hostile environment, lack of easily accessible resources, and isolation. In 1895, the first confirmed landing was conducted by a team of Norwegians.

Antarctica is a de facto condominium, governed by parties to the Antarctic Treaty System that have consulting status. Twelve countries signed the Antarctic Treaty in 1959, and thirty-eight have signed it since then.

The treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continent’s ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations.