No matter how much the world cuts back on carbon emissions, a key and sizable chunk of Antarctica is essentially doomed to an 鈥渦navoidable鈥 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 study鈥檚 lead author said.
Researchers used computer simulations to calculate future melting of protective ice shelves jutting over Antarctica鈥檚 Amundsen Sea in western Antarctica. The study in Monday鈥檚 journal found even if future warming was limited to just a few tenths of a degree more 鈥 an international goal that many scientists say is unlikely to be met 鈥 it would have 鈥渓imited power to prevent ocean warming that could lead to the collapse of the West Antarctic Ice Sheet.鈥
鈥淥ur 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?鈥 said study lead author Kaitlin Naughten, an oceanographer at the British Antarctic Survey. 鈥淯nfortunately, it鈥檚 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.鈥
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, there鈥檚 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 鈥 the international goal 鈥 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
Naughten鈥檚 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 鈥渋s doomed,鈥 said University of California Irvine ice scientist Eric Rignot, who wasn鈥檛 part of the study. 鈥淭he damage has already been done.鈥
University of Colorado ice scientist Ted Scambos, who also wasn鈥檛 part of the study, said this ice sheet 鈥渆ventually is going to collapse. It鈥檚 not a happy conclusion and it is one that I鈥檓 only saying reluctantly.鈥
Naughten doesn鈥檛 like to use the word 鈥渄oomed,鈥 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 what鈥檚 happening now on the ground is a slow collapse that can鈥檛 be stopped, at least not in this century.
鈥淚 think it鈥檚 unavoidable that some of this area is lost. It鈥檚 unavoidable that the problem gets worse,鈥 Naughten told The Associated Press. 鈥淚t isn鈥檛 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 鈥渃ouldn鈥檛 be saved or a lot of it couldn鈥檛 be saved.鈥
Naughten鈥檚 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 鈥渁bsolutely devastating鈥 if it happened over 200 years, but if it could be stretched out over 2,000 years, humanity could adapt, Naughten said.
鈥淐oastal communities will either have to build around or be abandoned," Naughten said.
While this part of Antarctica鈥檚 ice sheet is destined to be lost, other vulnerable sections of Earth鈥檚 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 香港六合彩挂牌资料 Snow and Ice Data Center who wasn鈥檛 part of the research, said she worries that most people will see nothing but doom and gloom in the research.
鈥淚 don鈥檛 see a lot of hope,鈥 Naughten said. 鈥淏ut it鈥檚 what the science tells me. So that鈥檚 what I have to communicate to the world.鈥
Naughten quoted former NASA scientist Kate Marvel, saying 鈥渨hen 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.鈥
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