Future Antarctic ice shelves strongly dependent on human actions

/ October 12, 2015/ Ice and Climate, IMAU

 

Antarctic ice shelves

If we reduce the emission of greenhouse gases, then a number of Antarctic ice shelves may be saved by the end of the century. If we don’t, then the collapse of the ice shelves will result in additional sea-level rise. That is the result of an American study conducted in cooperation with researchers from Utrecht University and the KNMI. These results will be published on 12 October in the scientific journal Nature Geoscience.

In their study, the researchers compare two scenarios for the amount of surface snowmelt in Antarctica: one with an average reduction in the amount of CO2 emissions, and another without a reduction in emissions. Both scenarios show that the amount of snowmelt on Antarctica will double between now and 2050. In the emission reduction scenario, the amount of snowmelt will level off after 2050, but without reductions the amount of melt will reach eight times the current levels by the year 2100. This could result in the breakup of several large ice shelves.

Worrisome, yet hopeful

“The results are worrisome, but at the same time hopeful”, according to Dr. Peter Kuipers Munneke, polar meteorologist at Utrecht University and meteorologist for the Dutch Public Broadcasting System. “We know that melting snow can endanger the ice shelves. This study shows just how rapidly snowmelt will increase as the global temperature rises. On the other hand, we have shown that limiting the increase in temperature within a few decades will eliminate a major source of rising sea levels. This may be a motivating message for the international climate negotiations in Paris in December.”

Ice-shelf collapse

Ice shelves, some of them as large as the Netherlands, are the parts of the Antarctic ice sheet that float on the ocean. Meltwater collects on these ice shelves in large meltwater lakes and in deep crevasses. “If the pressure of all of that meltwater on the ice becomes too great, an ice shelf can disappear within a month as we have witnessed in 1995 and in 2002, with the collapse of the Larsen A and B ice sheets”, Kuipers Munneke explains. “If temperatures continue to rise, the meltwater on some large ice shelves will increase to the point that a similar collapse will become inevitable. Glaciers that are currently slowed down by the ice shelf will then accelerate towards the sea, increasing sea levels worldwide.”

Future Antarctic ice sheet

“Our study clearly shows how sensitive the Antarctic ice sheet is for a warmer atmosphere”, adds Professor of Polar Meteorology Michiel van den Broeke from Utrecht University. “But we also see that the politicians and policy makers gathering in Paris actually have a clear choice when it comes to the future of the Antarctic ice sheet.”

This research was funded in part by Utrecht University, the Netherlands Earth System Science Centre (NESSC), the KNMI and the NWO’s Netherlands Polar Programme.

Publication

Divergent trajectories of Antarctic surface melt under two twenty-first-century climate scenarios
Luke D. Trusel, Karen E. Frey, Sarah B. Das, Kristopher B. Karnauskas, Peter Kuipers Munneke*, Erik van Meijgaard en Michiel R. van den Broeke*
Nature Geoscience, DOI: 10.1038/NGEO2563, 12 October 2015, 17:00 online

* Affiliated with the Institute for Marine and Atmospheric Research at Utrecht University.

More information

This research is a follow-up to a publication in the Journal of Glaciology, referred to in a previous press release.

Sustainability

This research falls under  ‘Water, Climate and Ecosystems‘, part of Utrecht University’s strategic theme Sustainability. More information about the research theme Sustainability.

Contact

Monica van der Garde, Press Officer, Faculty of Science, m.vandergarde@uu.nl, +31 (0)6 13 66 14 38.