Fate of world’s biggest ice sheet is in human hands, scientists say

Humans could prevent the demise of the world’s largest ice sheet by keeping global warming below a threshold set in the 2015 Paris climate accords, scientists declared on Wednesday.

The worst effects of climate change on the East Antarctic Ice Sheet might be avoidable if temperatures do not rise by more than 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, the researchers revealed in a new study in Nature.

As part of the Paris climate agreement — signed at the 2015 United Nations Climate Change Conference — participating countries agreed to adhere to this limit, with hopes of keeping the increase to an even smaller 1.5 degrees Celsius (2.7 degrees Fahrenheit).

Staying below the 2 degrees Celsius limit would ensure that the East Antarctic Ice Sheet, which holds most of the Earth’s glacier ice, contributes less than half a meter to sea level rise by the year 2500, according to the scientists.

But if warming continues to surge beyond that threshold, the ice sheet could contribute several meters to sea level rise in just a few centuries, the researchers warned.

“The fate of the East Antarctic Ice Sheet remains very much in our hands,” lead author Chris Stokes, a geography professor at the United Kingdom’s Durham University, said in a statement.

“This ice sheet is by far the largest on the planet, containing the equivalent of 52 meters of sea level and it’s really important that we do not awaken this sleeping giant,” he added.

Stokes worked with colleagues from the U.K., the U.S., Australia and France to assess the sensitivity of the ice sheet and examine the potential impacts of different emissions levels and temperatures on the ice sheet by 2100, 2300 and 2500.

Their analysis revealed that if warming persists beyond 2100, then the East Antarctic Ice Sheet could add several meters to global sea level rise over the coming centuries.

This surge would add to the already substantial contributions coming from Greenland and West Antarctica — potentially threatening millions of people worldwide who reside in coastal areas, according to the study.

“We used to think East Antarctica was much less vulnerable to climate change, compared to the ice sheets in West Antarctica or Greenland, but we now know there are some areas of East Antarctica that are already showing signs of ice loss,” Stokes said.

“Satellite observations have revealed evidence of thinning and retreating, especially where glaciers draining the main ice sheet come into contact with warm ocean currents,” he added.

While probing the history of the East Antarctica, the scientists said they also identified worrying signs that the ice sheet might be more sensitive than previously assumed.

They found evidence from sea floor sediments indicating that part of the sheet already collapsed and contributed several meters to sea level rise during the mid-Pliocene era, around 3 million years ago. This was also the last time that carbon dioxide concentrations in the atmosphere exceeded today’s values, according to the study.

But the researchers stressed that with a dramatic reduction in greenhouse gas emissions and only a small rise in temperature, humans still have the power to minimize East Antarctica’s ice loss.

“We now have a very small window of opportunity to rapidly lower our greenhouse gas emissions, limit the rise in global temperatures and preserve the East Antarctic Ice Sheet,” co-author Nerilie Abram, a professor at the Australian National University’s Research School of Earth Sciences, said in a statement.

“Taking such action would not only protect the East Antarctic Ice Sheet, but also slow the melting of other major ice sheets such as Greenland and West Antarctica, which are more vulnerable and at higher risk,” Abram added. “Therefore, it’s vitally important that countries achieve and strengthen their commitments to the Paris Agreement.”