Warm water rising from below threatens Antarctic ice sheets

A team of scientists has observed rising temperatures on the West Antarctic shelf.

The Antarctic ice sheet is a giant water reservoir. The ice cap on the southern continent is on average 2,100 meters thick and contains about 70 percent of the world's fresh water and if this ice mass were to melt completely, it could raise the global sea level by 60 meters.

Lead author Sunke Schmidtko said that there are many large glaciers in the area and the elevated temperatures have accelerated the melting and sliding of these glaciers in recent decades and there are no indications that this trend is changing.

For their study, he and his colleagues of the University of East Anglia, the California Institute of Technology and the University of Hokkaido (Japan) evaluated all oceanographic data from the waters around Antarctica from 1960 to 2014 that were available in public databases.

These data show that five decades ago, the water masses in the West Antarctic shelf seas were already warmer than in other parts of Antarctica, for example, in the Weddell Sea, however, the temperature difference is not constant.

Since 1960, the temperatures in the West Antarctic Amundsen Sea and the Bellingshausen Sea have been rising and Schmidtko added that based on the data they were able to see that this shelf process is induced from the open ocean.

Around Antarctica in greater depth along the continental slope water masses with temperatures from 0.5 to 1.5 degree C are predominant, which are very warm for Antarctic conditions.

Schmidtko continued that these waters have warmed in West Antarctica over the past 50 years and they are significant shallower than 50 years ago, especially in the Amundsen Sea and Bellingshausen Sea they now increasingly spill onto the shelf and warm the shelf.

The study is published in journal Science.