It has been estimated that 70 percent of the earth’s fresh water is tied up in the Antarctic ice cap. When you realize that near the south pole the surface of the ice is 15,000 feet above sea level, you start to understand how Antarctica can act as a temperature buffer to help stabilize global temperature swings. The weight of the ice is so great that it is estimated that it has pushed some of the bedrock down more than 8,000 feet below sea level.
What would Antarctica look like without the ice? It’s hard to say. The molten ice would raise the level of the oceans by some 200 feet, but the land mass, relieved of its burden would spring back up over time. This image from Wikipedia gives some idea of how much of the underlying bedrock would be above water.
But from the moment we saw our first small iceberg float out of the mist as we neared the South Shetland Islands ’til we entered the Drake Passage for our return to civilization, we were never out of sight of ice.
There were glaciers of ice sliding down the mountains, chunks of ice floating in the sea, icebergs that dwarfed our little ship, and caps of ice concealing the islands beneath them. You could wake up in the middle of the night, peer out the porthole, and see sheets of ice glistening in the moonlight.
How Old is this Ice?
Antarctica has been under its ice cap for the past five million years. The central area gets around two inches of precipitation a year (similar to the Mojave Desert). It probably takes tens of thousands of years for those snowflakes to work their way out to the edge of the continent and break off as part of an iceberg. Deeper ice has been dated to 400,000 years ago. Snowfall in the Peninsula, where we were, is much heavier, and the glaciers move faster, taking a thousand years or so to make their way to the sea.
The ice cap extends out over the ocean in ice shelves. Recent research has shown that some of these ice shelves are retreating at an unexpected rate due to global warming.