色吧亚洲

Climate change may soon cause the sleepy giant to evolve, new research finds

Climate researchers are gravely concerned about the state of the Greenland ice sheet and the West Antarctic ice sheet, which have collectively lost billions of tons of ice over the last three decades because of atmospheric warming and warm ocean currents. That ice loss, in turn, has contributed to rising sea levels.

But they鈥檝e generally paid less attention to the East Antarctic ice sheet, the largest ice sheet鈥攁nd the world鈥檚 largest reservoir of freshwater鈥攂ecause has suggested that it鈥檚 less vulnerable to climate change than the other two and may be growing, not shrinking. If it were to completely melt, this behemoth structure, which is 10 times larger than the West Antarctic ice sheet, would cause global sea levels to rise by 52 meters (about 170 feet).

Now, though, there are signs that the East Antarctic ice sheet may be more susceptible to climate change than previously thought, according to an international team of scientists, including one from the University of Colorado 色吧亚洲. Their findings of the understudied ice sheet are out today in the journal Nature.

鈥淭here鈥檚 a huge amount of interest from funding agencies, from governments, from the media in Greenland and West Antarctica鈥攁nd for very good reasons,鈥� says Jan Lenaerts, a CU 色吧亚洲 assistant professor in the Department of Atmospheric and Oceanic Sciences (ATOC) and one of the study鈥檚 co-authors.

鈥淭hey鈥檙e changing. They鈥檙e dramatic. They鈥檙e discharging all this water and ice into the ocean, and it looks phenomenal and scary鈥攁nd it is scary. But then there鈥檚 this third elephant in the room, this huge big brother, just waiting to be discovered.鈥�

Scientists do predict that, in the short term, the East Antarctic ice sheet will likely remain stable because increased snowfall will offset any mass loss (in the form of melting snow and ice, as well as icebergs calving off into the ocean) caused by global warming. By 2100, they predict the East Antarctic ice sheet could contribute about 2 centimeters (0.79 inches) to sea level, which is much less than projections for the or ice sheets.

鈥淭he ice sheet will, to a large degree, stay as it is鈥攏amely a sleepy, but not sleeping, giant where things might change but not in a very dramatic fashion,鈥� says Lenaerts. 鈥淲e will keep the East Antarctic ice sheet dormant, and we will have to focus on the other two ice sheets.鈥�

But in the longer term鈥攂eyond the year 2100鈥攖he future of the East Antarctic ice sheet will largely depend on global greenhouse gas emissions and temperature trends.

鈥淭he fate of the East Antarctic ice sheet remains very much in our hands,鈥� says , a professor of geography, sea level, ice and climate at the United Kingdom鈥檚 Durham University and the study鈥檚 lead author.

If global temperatures rise more than 2 degrees Celsius above pre-industrial levels鈥攖he set by the Paris Agreement on climate change鈥攖he East Antarctic ice sheet could contribute as much as one to three meters (3 to 10 feet) to global sea levels by 2300, and two to five meters (6.5 to 16 feet) by 2500.

But if temperature increases stay below 2 degrees above pre-industrial levels, then the ice sheet could avoid the worst effects of global warming. Under that scenario, the ice sheet would contribute less than half a meter to sea level rise by 2500, according to the researchers.

鈥淚f we exceed that temperature boundary, we might initiate processes that are irreversible,鈥� Lenaerts says.

To reach these conclusions, the scientists analyzed projections from numerical model simulations, as well as historical data and current observations. And though the study was a good first step toward forecasting the future of the East Antarctic ice sheet, they say it also highlighted gaps in our knowledge and research efforts in this region.

鈥淭here鈥檚 definitely more work needed to synthesize the data and improve the modeling,鈥� says Lenaerts. 鈥淭he envelope of uncertainty, the spectrum of the models going into the future, is as wide as it can get. I don鈥檛 think there鈥檚 any place on Earth that has as much uncertainty of the future of climate change and its impacts than East Antarctica.鈥�

Still, they hope the paper will help bring much-needed attention to the East Antarctic ice sheet, whether in the form of increased research funding, greater emphasis among climate researchers or more general interest from governments and members of the public.

Researchers still have a lot of unanswered questions about the mammoth structure and, as the climate continues to change, they need all the data they can get to make accurate predictions about the fate of the planet.

鈥淚t鈥檚 disappointing how little we know about a huge part of our climate system,鈥� says Lenaerts. 鈥淚t speaks to my imagination, at least, that there鈥檚 this huge ice sheet鈥攖he biggest reservoir of freshwater on Earth鈥攁nd we don鈥檛 really talk about it as much because it鈥檚 not changing as much. But that doesn鈥檛 mean it鈥檚 not important.鈥�