A long crack is seen across the Larsen C Ice Shelf, as seen by the Operational Land Imager on the NASA/USGS Landsat 8 spacecraft in 2017, is one of the largest remaining shelves in Antarctica -- but researchers are worried about the threat that warmer temperatures pose to its health. File Photo by NASA/UPI | License Photo
April 7 (UPI) -- If global temperatures reach 4 degrees Celsius above preindustrial levels, more than a third of Antarctic's ice shelves will be at risk of collapse, according to new models detailed Thursday in the journal Geophysical Research Letters.
Modeling the potential collapse of Antarctica's ice shelf is key to forecasting global sea level rise, said climate scientists at Britain's University of Reading.
The new simulations showed, specifically, that more than two-thirds of the ice shelf on the Antarctic Peninsula would be at risk of collapse under a severe warming scenario.
Conversely, if warming is limited to 2 degrees, simulations suggest the risk of collapse along Antartica's coast can be halved and accelerated sea level rise can be avoided.
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Should the continent's ice shelves collapse, Antarctica's interior ice sheet would become increasingly exposed to warm air and water, further accelerating melt rates and sea level rise.
While the collapse of a third of Antarctica's ice shelves sounds dramatic, paleoclimate data suggests ancient warming events have previously triggered the rapid loss of ice shelves, ice sheets and glaciers.
Currently, Antarctica's ice shelves serve as a protective buffer, insulating interior glaciers from warm water currents and rising atmospheric temperatures.
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The ice shelves also work like a dam, counteracting gravity's influence on southern continent's interior ice.
Even without continued warming, destabilization of Antarctica's ice shelf would guarantee accelerated melt rates and sea level rise for a century or more.
"We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly," study lead author Ella Gilbert, climate scientist at the University of Reading in Britain, said in a press release.
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"Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modeling techniques to fill in the finer detail and provide more precise projections," said Gilbert, a climate scientist at the University of Reading.
"The findings highlight the importance of limiting global temperature increases as set out in the Paris Agreement if we are to avoid the worst consequences of climate change, including sea level rise," Gilbert said.
Gilbert developed the new models to isolate the effects of warming trends on the fracturing process inside Antarctica's ice shelf. The simulations considered three global warming scenarios: warming of 1.5, 2 and 4 degrees Celsius.
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Every year, meltwater runoff cleaves holes and crevices in the large expanses of ice that stretch into the Southern Ocean. New snow and refrozen meltwater often fills theses gaps, but when meltwater rates outpace new snow, these gaps can grow larger and larger.
Eventually, these widening crevices can cause parts of the ice shelf to collapse.
In 2017, this process caused a massive iceberg to cleave into the ocean from Antarctica's Larsen C ice shelf, leaving the shelf vulnerable to further breakdown.
In 2002, Larsen C's neighbor, the Larsen B ice shelf, disintegrated in the wake of a similarly dramatic breakaway.
The newest simulations showed that the Larsen C, Shackleton, Pine Island and Wilkins ice shelves are most at risk of collapse under accelerated warming scenarios.
"If temperatures continue to rise at current rates, we may lose more Antarctic ice shelves in the coming decades," Gilbert said. "Limiting warming will not just be good for Antarctica -- preserving ice shelves means less global sea level rise, and that's good for us all."
Scientists measure ocean currents underneath 'Doomsday Glacier'
The calving front of Thwaites Ice Shelf, with a view of the ice below the water's surface, as seen from the NASA DC-8 in 2012. Photo by James Yungel/NASA/Flickr
April 9 (UPI) -- For the first time, climate scientists have measured ocean conditions beneath Antarctica's Thwaites Glacier, sometimes called the "Doomsday Glacier."
The fresh observations, published Friday in the journal Science Advances, show Thwaites is exposed to larger amounts of warm water than previously estimated.
Thwaites is thought to be one of the West Antarctic Ice Sheet's most vulnerable glaciers, its location and structure making it especially susceptible to influxes of warm, salty water.
In recent years, scientists have watched its grounding line recede and its height shrink as melting rates accelerate.
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To better understand the vulnerabilities of the glacier's underbelly, scientists sent a remote-controlled submersible named Ran beneath the ice shelf to investigate.
"This was Ran's first venture to polar regions and her exploration of the waters under the ice shelf was much more successful than we had dared to hope," study co-author Karen Heywood said in a news release.
"We plan to build on these exciting findings with further missions under the ice next year," said Heywood, a professor of physical oceanography at the University of East Anglia.
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Ran measured current speeds, as well as water temperature, salinity and oxygenation, at a variety of depths beneath Thwaites.
The data helped scientists mapped the movement of underwater currents in the region, revealing a large volume of deep water flowing toward the Antarctic coast from Pine Island Bay -- a pathway scientists previously thought was blocked by a ridge.
The discovery suggests Thwaites is vulnerable to a larger supply of warm water than previously estimated.
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"The channels for warm water to access and attack Thwaites weren't known to us before the research," said co-author Alastair Graham, climate scientist at the University of South Florida.
"Using sonars on the ship, nested with very high-resolution ocean mapping from Ran, we were able to find that there are distinct paths that water takes in and out of the ice shelf cavity, influenced by the geometry of the ocean floor," Graham said.
Thwaites is one of several coastal glaciers slowing the descent of the West Antarctic Ice Sheet into the Southern Ocean.
Currently, the ice sheet is responsible for just 10 percent of global sea level rise, but that number would surely increase -- and rapidly -- if Thwaites or one of its neighbors collapse.
The underwater data collected by Ran also revealed a diverse array of meltwater flows surrounding the pinning points, the areas where the bottom of the glacier anchors on the seabed -- areas critical to the ice shelf's overall stability.
"This work highlights that how and where warm water impacts Thwaites Glacier is influenced by the shape of the sea floor and the ice-shelf base as well as the properties of the water itself," said co-author Rob Larter of the British Antarctic Survey.
"The successful integration of new sea-floor survey data and observations of water properties from the Ran missions shows the benefits of the multidisciplinary ethos within the International Thwaites Glacier Collaboration," Larter said.
The future of Antartica's ice sheets, and their influence on global sea level rise remains one of climate science's largest uncertainties, but the study's authors suggest the latest data will help them develop more accurate forecasting models.
The calving front of Thwaites Ice Shelf, with a view of the ice below the water's surface, as seen from the NASA DC-8 in 2012. Photo by James Yungel/NASA/Flickr
April 9 (UPI) -- For the first time, climate scientists have measured ocean conditions beneath Antarctica's Thwaites Glacier, sometimes called the "Doomsday Glacier."
The fresh observations, published Friday in the journal Science Advances, show Thwaites is exposed to larger amounts of warm water than previously estimated.
Thwaites is thought to be one of the West Antarctic Ice Sheet's most vulnerable glaciers, its location and structure making it especially susceptible to influxes of warm, salty water.
In recent years, scientists have watched its grounding line recede and its height shrink as melting rates accelerate.
RELATED Map reveals land beneath Antarctic ice sheet in unprecedented detail
To better understand the vulnerabilities of the glacier's underbelly, scientists sent a remote-controlled submersible named Ran beneath the ice shelf to investigate.
"This was Ran's first venture to polar regions and her exploration of the waters under the ice shelf was much more successful than we had dared to hope," study co-author Karen Heywood said in a news release.
"We plan to build on these exciting findings with further missions under the ice next year," said Heywood, a professor of physical oceanography at the University of East Anglia.
RELATED Calving to leave Thwaites Glacier increasingly vulnerable to collapse
Ran measured current speeds, as well as water temperature, salinity and oxygenation, at a variety of depths beneath Thwaites.
The data helped scientists mapped the movement of underwater currents in the region, revealing a large volume of deep water flowing toward the Antarctic coast from Pine Island Bay -- a pathway scientists previously thought was blocked by a ridge.
The discovery suggests Thwaites is vulnerable to a larger supply of warm water than previously estimated.
RELATED Antarctic ice instability could yield rapid melting, dramatic sea level rise
"The channels for warm water to access and attack Thwaites weren't known to us before the research," said co-author Alastair Graham, climate scientist at the University of South Florida.
"Using sonars on the ship, nested with very high-resolution ocean mapping from Ran, we were able to find that there are distinct paths that water takes in and out of the ice shelf cavity, influenced by the geometry of the ocean floor," Graham said.
Thwaites is one of several coastal glaciers slowing the descent of the West Antarctic Ice Sheet into the Southern Ocean.
Currently, the ice sheet is responsible for just 10 percent of global sea level rise, but that number would surely increase -- and rapidly -- if Thwaites or one of its neighbors collapse.
The underwater data collected by Ran also revealed a diverse array of meltwater flows surrounding the pinning points, the areas where the bottom of the glacier anchors on the seabed -- areas critical to the ice shelf's overall stability.
"This work highlights that how and where warm water impacts Thwaites Glacier is influenced by the shape of the sea floor and the ice-shelf base as well as the properties of the water itself," said co-author Rob Larter of the British Antarctic Survey.
"The successful integration of new sea-floor survey data and observations of water properties from the Ran missions shows the benefits of the multidisciplinary ethos within the International Thwaites Glacier Collaboration," Larter said.
The future of Antartica's ice sheets, and their influence on global sea level rise remains one of climate science's largest uncertainties, but the study's authors suggest the latest data will help them develop more accurate forecasting models.
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