According to a new report, the melting of Antarctic ice sheets, especially one of the largest and most unstable glaciers in the region, could significantly accelerate sea level rise worldwide.
Climatologists who have measured the likely results of melting glaciers at the bottom of the world have focused their study on the Thwaites Glacier, a region as large as Florida in West Antarctica and considered the most unstable on the continent.
The study revealed that even if no climate change would occur in the future, more Antarctic ice caps may become unstable. He also says that as the destabilization of glaciers in Antarctica continues, it is increasingly likely that sea levels will rise more rapidly.
"Due to past climate change, there will certainly be some sea level rise in the future," Alex Robel, a glaciologist and assistant professor at Georgia Institute of Technology Technology, told TIME. He and two other scientists from the California Institute of Technology and the University of Washington wrote the report published by the National Academy of Sciences.
Earlier this year, a study conducted by NASA revealed that a giant cavity, two-thirds of the Manhattan area, had developed under Thwaites, highlighting the unexpected accelerated melting in the region.
"It is really painful, on a human level, to think or to realize that there is a certain level of retreat in terms of sea level rise that we have already engaged in. 'future,' added Robel.
The amount of ice leaving the region has almost doubled in the last 30 years, losing 35 gigatonnes of ice per year between 2009 and 2017 alone. This equates to 3% of the current rate of sea level rise according to Robert Larter, Marine Geophysicist at the British Antarctic Survey.
The sea ice caps, which form when the warmer seawater melts the area between the sea floor and the ice that creates a cavity, may collapse. Scientists are worried that the remaining ice will melt faster.
"It's a 3% contribution that was not there 45 years ago," Larter said at TIME. He says all the ice in the Thwaites Glacier could raise the global sea level by just over two feet. "If you have destroyed an entire glacial system, you are creating a new front on the other glacial systems that were adjacent to it. Things are definitely not going to stop there, "said Larter.
Sea level is currently increasing by 3.3 millimeters a year and 91 millimeters since 1993, according to NASA.
What did the study show exactly?
Robel, along with scientists Helene Seroussi and Gerard Roe, used mathematical analysis and computer models to make sea level projections in the future. They wanted to understand how possible scenarios of future sea level rise could evolve over time due to the instability of the sea ice cap.
"The more this instability of the sea ice sheet occurs, the greater the range of future sea level rise becomes possible," says Robel. "Not only that, but this range will start to skew towards scenarios of faster sea level rise."
When they tested these predictions with the help of a computer model of Thwaites Glacier, they came to the same conclusion. The simulations confirmed what scientists such as Larter observed during field expeditions in Western Antarctic and previous modeling studies of the Thwaites Glacier, which had shown that the glacier was becoming more and more unstable.
These simulations also show that future expeditions have an important role to play in trying to reduce Thwaites' potential sea level rise scenarios, says Robel.
"There will always be a level of uncertainty in our future projections, but that does not mean we do not know some very important things," he added. For example, it is certain that sea level will continue to rise because of past climate change, he said. "We must keep in mind that our future actions can dramatically alter the magnitude of sea level rise in the future."
"The overall picture shows that there are jokers in the game here and the more we learn in recent years, the more uncertainties are increasing," said Larter, who studied Antarctica for 15 years. years and went to Thwaites for scientific reasons. shipments with the International Thwaites Glacier Collaboration, a partnership of American and British scientists, says. "One of the goals of what we do as scientists is to try to limit uncertainties and give better predictions, but in some ways, the more we discover that the more uncertainties we find."
What does ice sheet instability mean for the future of Antarctica and the world?
West Antarctica has the potential to increase sea level by 5 meters, while East Antarctica can feed 50 to 60 meters in the event of a complete melting of ice, said TIME Anders Levermann, climatologist at the Institute for Research on Climate Impacts in Potsdam, Germany. To put this into perspective, there has been about 20 centimeters of sea level rise over the last 100 to 120 years, according to Levermann.
Since 1992, satellite observations for the Antarctic have revealed that ice sheets contribute to sea level rise around the world. Most of the loss of Antarctic ice comes from West Antarctica.
What is still uncertain is how quickly the continent is losing ice or whether the instability of Thwaites' sea ice cap is a result of climate change, but Mr Levermann says that there is nothing just not enough research to be sure.
"It is very curious that nothing has happened for 10,000 years in Western Antarctic, and now [unstable] 100 years after starting to play with the temperature of the planet, "says Levermann. "The more we warm the planet, the more we lose ice."
He added that there were more marine ice caps in Antarctica that could become destabilized if warming continued.
According to Dr. Levermann, scientists will know more over the next 20 years at the current rate of research. He adds that the world must prepare for a significant rise in sea level by 2100 and monitor the developments in Antarctica and Greenland.
The Intergovernmental Panel on Climate Change predicts a sea level rise of 0.26 to 0.77 meters by 2100 if warming increases by 1.5 ° C compared to pre-industrial temperatures (19th century) or 2.7 degrees Fahrenheit. According to Larter, the global temperature has already increased by about 1 degree Celsius since the pre-industrial era, which means that there is only about 0.5 degree left for the global temperature to increase.
Why is sea level rise important?
"Regardless of the fact that this was triggered by man – which is an obvious possibility without scientific evidence at the moment – but apart from that, we are increasing the risk of sea level rise. and an acceleration of sea level rise since Antarctica with a warming planet, "said Levermann.
Coastal cities around the world are threatened if sea levels continue to rise. Robel says countries around the world need to be aware that there will be a rise in sea level and that they have to prepare for it by adapting the infrastructure and taking action. which will avoid aggravating the problem.
"Nobody should be afraid of rising sea level. If you are not stupid, you will not die of sea level rise, because it is so slow that it is time to protect yourself or abandon the land, "says Levermann. "That being said, being stupid would mean not taking climate change and rising sea levels seriously."