Even more amazing, it wasn’t until the mid-2010s that Antarctic sea ice reached a record high. tops– at least highs since satellite observations began – having increased slightly but steadily over the years since 1979.
This recent growth of Antarctic sea ice contrasts sharply with that of the Arctic, a region that is currently warming up to four times faster than the rest of the planet and has been steadily losing ice for decades. It is due to a phenomenon called arctic amplification: Melting ice exposes darker ocean or land waters, which absorb more solar energy than white ice, which in turn leads to increased warming.
Antarctica is a different beast: it’s a frozen continent surrounded by an open ocean, whereas the Arctic is an ocean of floating ice surrounded by land, like Russia, Alaska and northern Canada. Antarctica’s ice is insulated, in a sense, by strong cold ocean currents that swirl around the continent. In addition, the altitude of Antarctica is quite high, which provides additional cooling.
Antarctica’s sea ice, which forms when seawater freezes, is distinct from the continent’s ice caps and shelves. An ice cap sits on top of the earth and can be thousands of feet thick. It becomes an ice shelf when it begins to float on coastal waters. While the Antarctic ice caps and ice shelves have indeed been deteriorates as the planet heats upthe continent’s sea ice is much more seasonal, rising and falling dramatically between winter and summer.
Losing this sea ice will not raise sea level, just as melting ice cubes floating in a glass of water will not cause the glass to overflow. (Ice already displaces water.) But sea ice plays a critical role in protecting Antarctica’s colossal ice shelves from deterioration, and these could dramatically raise ocean levels if they do. were breaking. If it completely meltsThwaites Glacier, aka the Doomsday Glacier, could add 10 feet to sea level. Sea ice protects Thwaites and other glaciers because it acts as a buffer, absorbing wind and wave energy that would otherwise erode them. It also cools the air passing over coastal waters, further preventing the melting of ice shelves.
This year, the coast of West Antarctica has been particularly free of sea ice. “This is the area where climatologists are most concerned about the potential massive contributions of the ice sheet to sea level rise. “says Maksym. “This year we see absolutely no sea ice in this area, which I think is about the first time this has happened. Then there are some precedents studies it showed that if you remove the sea ice, you lose the kind of buttress effects, and it can accelerate the breakup of the pack ice.
But that’s not the only global effect the loss of sea ice will have: when seawater freezes into ice, the denser brine that remains sinks to the seafloor, creating deep currents that flow away from Antarctica. The less sea ice there is, the weaker these currents are. “This will affect how efficiently the oceans distribute energy and ultimately affect global climate,” says UCLA geographer Marilyn Raphael, who studies the region. “What happens in Antarctica doesn’t stay in Antarctica.”