No matter how much the world cuts back on carbon emissions, a key and sizable chunk of Antarctica is essentially doomed to an âunavoidableâ melt, a new study found.
Though the full melt will take hundreds of years, slowly adding nearly 6 feet (1.8 meters) to sea levels, it will be enough to reshape where and how people live in the future, the studyâs lead author said.
Researchers used computer simulations to calculate future melting of protective ice shelves jutting over Antarcticaâs Amundsen Sea in western Antarctica. The study in Mondayâs journal found even if future warming was limited to just a few tenths of a degree more â an international goal that many scientists say is unlikely to be met â it would have âlimited power to prevent ocean warming that could lead to the collapse of the West Antarctic Ice Sheet.â
âOur main question here was: How much control do we still have over ice shelf melting? How much melting can still be prevented by reducing emissions?â said study lead author Kaitlin Naughten, an oceanographer at the British Antarctic Survey. âUnfortunately, itâs not great news. Our simulations suggest that we are now committed to the rapid increase in the rate of ocean warming and ice shelf melting over the rest of the century.â
While past studies have talked about how dire the situation is, Naughten was the first to use computer simulations to study the key melting component of warm water melting ice from below, and the work looked at four different scenarios for how much carbon dioxide the world pumps into the atmosphere. In each case, ocean warming was just too much for this section of the ice sheet to survive, the study found.
Naughten looked at melting which float over the ocean in this area of Antarctica that is already below sea level. Once these ice shelves melt, thereâs nothing to stop the glaciers behind them from flowing into the sea.
Naughten specifically looked at what would happen if somehow future warming was limited to â the international goal â and found the runaway melting process anyway. The world has already warmed about 1.2 degrees Celsius (nearly 2.2 degrees Fahrenheit) since pre-industrial times and much of this summer temporarily
Naughtenâs study concentrated on the part of the West Antarctic Ice Sheet that is most at risk from melting from below, near the Amundsen Sea. It includes the massive Thwaites ice shelf that is melting so fast it got the nickname West Antarctica is only one-tenth of the southern continent but is more unstable than the larger eastern side.
That part of Antarctica âis doomed,â said University of California Irvine ice scientist Eric Rignot, who wasnât part of the study. âThe damage has already been done.â
University of Colorado ice scientist Ted Scambos, who also wasnât part of the study, said this ice sheet âeventually is going to collapse. Itâs not a happy conclusion and it is one that Iâm only saying reluctantly.â
Naughten doesnât like to use the word âdoomed,â because she said 100 years from now the world might not just stop but reverse carbon levels in the air and global warming. But she said whatâs happening now on the ground is a slow collapse that canât be stopped, at least not in this century.
âI think itâs unavoidable that some of this area is lost. Itâs unavoidable that the problem gets worse,â Naughten told The Associated Press. âIt isnât unavoidable that we lose all of it because sea level rise happens over the very long term. I only looked in this study up to 2100. So after 2100, we probably have some control still.''
No matter what words are used, Naughten said she and other scientists studying the area in previous research conclude that this part of Antarctica âcouldnât be saved or a lot of it couldnât be saved.â
Naughtenâs study did not calculate how much ice would be lost, how much sea level would rise and at what speed. But she estimated that the amount of ice in the area most at risk if it all melted would raise sea levels by about 1.8 meters (5.9 feet).
However, she said, that is a slow process that would play out through the next few hundred years through the 2300s, 2400s and 2500s.
Naughten said that may seem like a long way away, but noted that if the Victorians of the 1800s had done something to drastically change the shape of our world, we would not look well on them.
This type of sea level rise would be âabsolutely devastatingâ if it happened over 200 years, but if it could be stretched out over 2,000 years, humanity could adapt, Naughten said.
âCoastal communities will either have to build around or be abandoned," Naughten said.
While this part of Antarcticaâs ice sheet is destined to be lost, other vulnerable sections of Earthâs environment can still be saved by reducing heat-trapping emissions so there is reason to still cut back on carbon pollution, Naughten said.
Twila Moon, deputy chief scientist at the șĂÉ«tv Snow and Ice Data Center who wasnât part of the research, said she worries that most people will see nothing but doom and gloom in the research.
âI donât see a lot of hope,â Naughten said. âBut itâs what the science tells me. So thatâs what I have to communicate to the world.â
Naughten quoted former NASA scientist Kate Marvel, saying âwhen it comes to climate change we need courage and not hope. Courage is the resolve to do well without the assurance of a happy ending.â
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