Antarctica Is the World's Largest Desert

When most people picture a desert, they imagine vast stretches of sand, scorching heat, and almost no water. By that image, Antarctica — a frozen continent buried under ice — would seem like the opposite of a desert. In fact, Antarctica is the largest desert on Earth.

A desert is not defined by heat or sand. It is defined by precipitation — how much rain or snow falls in a given area each year. Any region that receives less than 250 millimetres of precipitation per year qualifies as a desert. By this definition, cold and dry places can be deserts just as readily as hot and sandy ones.

Antarctica receives an average of less than 200 millimetres of precipitation per year across the continent — and in its vast interior, some areas receive less than 50 millimetres. That is drier than most of the Sahara. The ice you see there is not the result of heavy snowfall; it has accumulated over millions of years, building up layer by layer in a place where almost nothing melts and almost nothing falls.

Antarctica covers approximately 14 million square kilometres, making it larger than Europe and nearly twice the size of Australia. The ice sheet covering it contains around 70 percent of all the fresh water on Earth. Yet despite holding so much frozen water, the continent is among the driest, windiest, and coldest places on the planet. Interior temperatures can fall below minus 80 degrees Celsius in winter, and winds can exceed 300 kilometres per hour.

Many people assume the Sahara is the world's largest desert. In terms of hot deserts, it is — covering about 9 million square kilometres across northern Africa. But it ranks third overall. The Arctic Desert, which covers the Arctic Ocean and surrounding land masses, comes in second at around 14 million square kilometres. Antarctica, at roughly the same size, takes first place.

Despite its extreme conditions, Antarctica is not lifeless. Penguins, seals, and seabirds thrive along its coasts, where the ocean provides food. Some microscopic organisms survive even in the dry valleys of the interior — regions so barren that scientists use them as analogs for the surface of Mars. The hardiest life on Earth does not merely survive in extreme conditions; it has found ways to flourish there.