Life and Death on the Crystal Desert
The Earth's most forbidding terrestrial climate, the southernmost continent of Antarctica, is so cold that its winter temperatures do not differ substantially from those on the surface of Mars. On the Antarctic plateau, the elevation averages 2300 meters (7500 feet), and gravitational katabatic winds whip strongly across the ice. The barometric pressure is lower than expected from the altitude on the plateau; effective altitude is 300 meters higher than true altitude and averages almost 2700 meters (9000 feet). Some regions receive less than two inches of snowfall per year, yet the ice sheet averages more than a mile (2 km) deep and pushes the land below sea level. Antarctica is the highest, coldest, driest, and windiest continent. It is also the world's fifth-largest continent, larger than Europe and Australia and one-and-a-half times the area of the United States (see Fig. 8.1). Most of the continent is technically a desert, even though it contains 70% of the fresh water and 90% of the ice on Earth.
Because most of Antarctica's surface is covered by ice, only about 2% is available for the growth of vegetation. There are no trees or shrubs and only two flowering plants: Antarctic hair grass and pearlwort. Antarctic floras consist mainly