A Land of Ice_______________________________
With 5,500,000 square miles of land, Antarctica lies 1 1⁄2 times larger than the United States. Ice averaging 7000 feet thick covers 99.6% of the continental landmass, depressing major mountain ranges under its heavy weight, making them invisible to our naked eye. Because this ice also accounts for 70% of the world’s fresh water, if Antarctica’s ice sheets were to ever melt, ocean levels would rise over 220 feet!
Not only is Antarctica an extremely large, icy covered continent, it is also very high and dry. It averages in elevation around 7300 feet. The South Pole itself lies a little over 9000 feet at 90˚S. With snow accumulation of less than 4 3⁄4 inches a year, Antarctica’s air is remarkably arid, making it a perpetual white desert. Cold, bitter winds prevail throughout the year; blowing snow down its ice shelves and towards the sea, packing it into what becomes some of the densest snow in the world.
In September, Antarctica’s late winter, the size of the continent effectively doubles with the freezing of the sea ice, where it can extend to more than 600 miles away from the coast. Found between 60˚ and 40˚S is the Antarctic Convergence, or the Polar Front, where cold water from the south converges with and sinks under the warm water from north. This marks the limit of the winter pack ice.
Though the overall thickness of the ice varies, by March most of the annual sea ice has broken up and melted back into its original liquid state. Just like an ice cube that melts in water, frozen sea ice displaces the amount of seawater equal to its weight, so water levels do not rise as the sea ice melts. The natural fractures in the frozen ice also mark areas where seals and penguins can surface and create breathing holes throughout the winter.
Antarctica is geographically divided by the long Transantarctic Mountain Range, distinctly separating Eastern Antarctica (or ‘Lesser Antarctica’) from Western Antarctica (‘Greater Antarctica’). Within this range is the highest point of the continent, Mt Vinson, standing at 15,680 feet.
Also of geographic significance, is the Western Antarctic Peninsula, which separates the two great embayments of the continent, the Weddell and the Ross Seas. Each of these has their own ice shelf, the Ronne and the Ross Ice Shelf respectively, with both extending of the great Antarctic ice sheet. The Ross Ice Shelf, roughly the size of France, is the world’s largest. It converges with the sea (or the sea ice during the austral winter), directly in front of McMurdo Station. Though its mean thickness is between 1000 and 2250 feet, its significantly less where it meets the Ross Sea, only around 320 feet thick. It’s amazing to think that these ice shelves are actually floating!