As we throw ourselves headlong into global warming, many people are talking about the fact that Arctic (North Pole) ice is melting at an alarming rate. But less discussed is the fact that as that ice melts away, the ice shelves in Antarctica are steadily growing larger each year. A recent study was released that examined the seemingly paradoxical situation in the South—as melt seasons get longer each year, more ice is forming.
The study, published by Nature Geoscience in March, is a peer-reviewed study out of the Royal Netherlands Meteorological Institute (KNMI). According to the study, as global warming increases so too will this trend of growing sea ice. The study hypothesizes that the fresh melt water from the ice shelves stays near the surface rather than sinking because its density is lower than that of the warmer saltwater below.
Ice shelves are very nearly salt-free, the salinity having been essentially rejected back into the water below. Therefore, as ice shelves melt, the water that comes off of them is fresh water—which has a lower density than saltwater. Water in any form is a poor conductor of heat. This freshwater layer, they hypothesize, will stay just below the ice shelves, helping to protect them from the deeper warm waters responsible for the ice melt. Then when autumn and winter arrive, those cool waters freeze more easily.
The climate implications of consistently expanding ice shelves in Antarctica could be great as well. More surface ice means a lower average air temperature. Cool air holds less moisture than warm air, meaning there could be less snowfall in Antarctica in the years to come.
Some believe that a potentially positive facet of this trend is that it could help offset global warming. Ice reflects heat from the sun back into space, helping to insulate the planet and protect it from a heat buildup. With more surface ice, more heat could be reflected back rather than absorbed. This is in direct contrast to what’s happening in the Arctic, where there is less ice and more dark melt water than ever before. The dark sea water absorbs heat rather than reflecting it, resulting in even faster melting.