A new study shows how much ice could be lost across Antarctica if the international community does not act quickly to reduce global warming emissions, bolstering calls for more aggressive climate policies.
Over a third of the area of all Antarctic ice shelves, including 67 percent of the area on the Antarctic Peninsula, may be at risk of collapsing if global temperatures rise to 4°C above pre-industrial levels, according to a report published Thursday in the journal Geophysical Research Letters.
The study is titled "Surface Melt and Runoff on Antarctic Ice Shelves at 1.5°C, 2°C and 4°C of Future Warming."
ANTARCTICA - OCTOBER 27: Ice floats near the coast of West Antarctica viewed from a window of a NASA Operation IceBridge airplane on October 27, 2016, in-flight over Antarctica. NASA's Operation IceBridge has been studying how polar ice has evolved over the past eight years and is currently flying a set of 12-hour research flights over West Antarctica at the start of the melt season. Researchers have used the IceBridge data to observe that the West Antarctic Ice Sheet may be in a state of irreversible decline directly contributing to rising sea levels. NASA and the University of California, Irvine (UCI) researchers have recently detected the speediest ongoing Western Antarctica glacial retreat rates ever observed. The United Nations climate change talks begin November 7 in the Moroccan city of Marrakech.
An ice shelf, as NASA explains, "is a thick, floating slab of ice that forms where a glacier or ice flows down a coastline." They are found only in Antarctica, Greenland, Canada, and the Russian Arctic-and play a key role in limiting sea-level rise.
"Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea-level rise," explained Ella Gilbert, the study's lead author, in a statement.
"When they collapse, it's like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea."
"We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly," added Gilbert, a research scientist at the University of Reading.
Previous research has provided researchers a bigger picture in terms of forecasting Antarctic ice shelf loss. But researchers said the recent study uses the most up-to-date modeling techniques to fill in the finer details and provide more accurate predictions.
Can we Limit Global Temperature Rise to 2°C?
According to Gilbert and co-author Christoph Kittel of the University of Liège in Belgium, restricting global temperature rise to 2°C rather than 4°C sea-level the region at risk by half.
Gilbert wrote in The Conversation that only 14 percent of Antarctica's ice shelf area will be threatened at 1.5 degrees Celsius.
According to the United Nations, while the 2015 Paris climate agreement seeks to keep temperature rise "well below" fewer with a more optimistic 1.5°C sea-level emissions reduction efforts are significantly out of line with both targets.
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The results of their new report, according to Gilbert, "highlight the urgency of restricting global temperature rises as set out in the Paris agreement if we are to prevent the worst effects of climate change, including sea-level rise," as stated in the Paris agreement.
Gilbert explained that the planet will lose more Antarctic ice shelves in the coming decades if temperatures continue to rise at current rates.
Because of their geography and runoff forecasts, the researchers warn that Larsen C, the largest remaining ice shelf on the Antarctic peninsula, as well as the Shackleton, Pine Island, and Wilkins ice shelves, are the most vulnerable to 4°C warmings.
Gilbert said that limiting warming would benefit us all, not just Antarctica." Preserving ice shelves means less global sea-level rise, which is good for everyone, she added.
What About the Low-Lying Coastal Regions?
According to Gilbert, low-lying coastal regions, such as Vanuatu and Tuvalu in the South Pacific Ocean, are the most vulnerable to sea-level rise.
However, she warned that coastal areas across the world would be vulnerable. Gilbert added that countries with fewer resources to mitigate and adapt to sea-level rise would suffer worse consequences."
Sea level rise predictions for this century "are on the money when measured against satellite and tide-gauge measurements," according to research published in February that looked at estimates from the United Nations Intergovernmental Panel on Climate Change's Fifth Assessment Report and the Special Report on the Ocean and Cryosphere in a Changing Climate.
A co-author of that study, John Church of the Climate Change Research Center at the University of New South Wales, said at the time that "if we continue with large ongoing emissions as we are at present, we will commit the world to meters of sea-level rise over coming centuries."
Parties to the Paris Agreement are updating their carbon reduction commitments, known as nationally determined contributions, in preparation for the United Nations Climate Summit in November, dubbed COP26.
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