In a warmer world, the ice masses in East Antarctica will grow
With regard to the Antarctic, the models’ results are much more varied. If greenhouse-gas emissions remain consistently high (RCP8.5), they predict that the Antarctic will contribute anywhere from -7.8 to 30.0 centimetres to global sea-level rise. What the minus symbol indicates: some models predict a significant decline in the Antarctic’s contribution to sea-level rise, even if the area and volume of ice in the Antarctic shrink. “These simulations show that, in a warmer world, there would be so much snowfall in East Antarctica that the new ice formed there would outweigh the ice lost to the warming seawater in West Antarctica,” explains AWI ice-sheet modeller Dr Thomas Kleiner, who also participated in the study.
For West Antarctica, the models predict ice losses that would produce an additional sea-level rise of up to 18.0 centimetres by 2100. However, if we succeeded in reaching the goals of the Paris Agreement and limiting global warming to well below 2 degrees Celsius (RCP2.6), the ice losses in the Antarctic would be significantly less, producing an additional sea-level rise of between -1.4 and 15.5 centimetres.
How should these results be interpreted? “For the past 40 years, we’ve observed a clear downward trend in the Antarctic. The ice sheet is losing more and more ice, especially in West Antarctica, where our models also predicted major losses of ice. That being said, the acceleration of the glaciers simulated in the models was much less pronounced than what we actually observed,” says Prof Angelika Humbert, a co-author of the study and Head of the AWI’s Ice Modelling group. Moreover, the experts see indications that the models overestimate future ice growth in East Antarctica. “If our suspicions prove to be true, it will also mean that the models underestimate how much Antarctica as a whole will contribute to future sea-level rise,” she underscores.