Andrew Freedman writes:

The Southern Ocean is one of the most important yet least explored and understood regions of the planet when it comes to determining how global warming may affect the future of humanity, thanks to its capacity to absorb huge quantities of heat and carbon dioxide, and melt swaths of the Antarctic ice sheet.

In addition, this vast ocean, part of which separates Australia and Antarctica and also circles the frozen continent, is where global ocean currents get started, as heat is exchanged between the ocean and atmosphere, salinity differences arise in various layers of the deep, storm-churned waters, and currents reaching the North Atlantic Ocean and beyond are powered.

In recent years, understanding how the Southern Ocean is changing as a result of increased greenhouse gas emissions has taken on greater urgency as scientists have learned more about the fragility of large parts of the Antarctic ice sheet, since glaciers extending into the ocean are being eroded by relatively mild waters below. Like removing a doorstop, the collapse of these ice shelves can free up inland ice to move into the ocean, raising global sea levels and harming coastal communities.

Now a new study, published Thursday in the journal Nature Communications, finds that beneath the surface layer of waters circling Antarctica, the seas are warming much more rapidly than previously known. Furthermore, the study concludes, this relatively warm water is rising toward the surface over time, at a rate three to 10 times what was previously estimated. [Continue reading…]