Antarctica's Shallow Seas Warming Up

To add to the wealth of research on climate change and how increasing temperatures are causing Antarctic (as well as Arctic) sea ice to melt, a new study has found that Antarctica's shallow seas are now warming up as heat from the deep rises.

Ocean waters around Antarctica have warmed steadily for the past 50 years, researchers reported in the journal Science, with some shallow areas heating up more quickly than others. West Antarctica, where ice melt has tripled, is particularly vulnerable.

The Weddell Sea, for example, was already warmer than other parts of the continent five decades ago. And in the region's Bellingshausen and Amundsen seas, seawater above 4,920 feet deep (1,500 meters) warmed from about 1.4 degrees Fahrenheit (0.8 Celsius) in the 1970s to about 2.2 degrees F (1.2 C) in the 2010s.

"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," lead author Dr. Sunke Schmidtko, from GEOMAR Helmholtz Centre for Ocean Research Kiel, said in a press release.

While previous research has found that deep offshore currents have experienced rapid warming, this latest study shows the dramatic effect warmer shallow seas can have. This refers to waters on the continental shelf which are situated under Antarctica's floating sea ice.

Researchers aren't exactly sure why warm water masses are rising into shallow seas, but they suspect changes in wind systems over the Southern Hemisphere has something to do with it.

Earth's oceans absorb heat from the atmosphere, and in Antarctica as the heat rises, it makes it easier for this warm ocean water to reach the continental shelf and melt glaciers.

"These waters... are significantly shallower than 50 years ago," Schmidtko explained. "Especially in the Amundsen Sea and Bellingshausen Sea they now increasingly spill onto the shelf and warm the shelf."

The Antarctic ice sheet contains 70 percent of the world's freshwater, so if this massive slab were to completely melt, it threatens to raise global sea levels by a whopping 197 feet (60 meters).

And while Antarctica's land ice is melting, its seasonal sea ice is growing slightly larger each winter, reaching record-breaking sea ice extent in September.

This continent is a good indicator of what we may expect in other parts of the world as our climate continues to change, and researchers plan to continue studying its shifting landscape.

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