Many people are surprised to learn that Antarctica is classified as a desert. In geographical terms, a desert is defined by its lack of precipitation, not its temperature. Antarctica receives an average of only 50 millimeters (about 2 inches) of precipitation per year, mostly in the form of snow. This makes it the largest desert in the world, covering 14.2 million square kilometers. It is also the coldest, windiest, and highest continent on Earth. About 98% of Antarctica is covered by ice that averages at least 1.9 kilometers in thickness. This ice sheet contains about 70% of the world's fresh water. If it were to melt entirely, global sea levels would rise by approximately 60 meters. Despite the extreme cold, some life exists here, primarily in the surrounding seas, including penguins, seals, and microscopic organisms in the ice-free Dry Valleys.