Why Are the Arctic and Antarctic Classified as Deserts?

The Frozen Wastes: Unpacking the Paradox of Polar Deserts

When most people hear the word "desert," their minds instantly conjure images of the blistering Sahara: endless undulating dunes, scorching sun, and camels navigating a landscape of intense heat. Yet, the two largest deserts on Earth are covered in miles of thick ice and experience temperatures that can drop to -80°C (-112°F). How did the frozen poles come to share a classification with the world's hottest arid lands?

The Linguistic and Scientific Root of 'Desert'

To understand this classification, we must look at the etymology of the word itself. Derived from the Latin desertus, meaning "abandoned" or "left waste" (from deserere, "to forsake"), the term historically referred to any uninhabited, desolate, or wild region—not necessarily a hot one.

In modern climatology, however, the definition shifted from poetic desolation to strict meteorological metrics. A desert is formally defined not by temperature, but by aridness—specifically, a region that receives an extremely low amount of annual precipitation (typically less than 250 millimeters or 10 inches per year).

The Physics of Polar Aridness

Both the Arctic and Antarctic fit this meteorological threshold with room to spare. Despite being surrounded by oceans of water, the air over the poles is intensely cold. Cold air holds significantly less moisture than warm air. As a result, the polar regions experience very little atmospheric humidity and receive meager snowfall—often less than 50 millimeters (2 inches) per year in the interior of Antarctica.

Ironically, the vast sheets of ice in Antarctica accumulated over millions of years precisely because it is a desert; the lack of moisture and freezing temperatures meant that whatever snow did fall never melted, slowly compacting over millennia into colossal ice caps. Because evaporation rates are also near zero, the little precipitation that does fall stays put, creating the illusion of abundant water where there is actually profound meteorological drought.

Historical Nuance in Exploration Literature

Early polar explorers like Robert Falcon Scott and Roald Amundsen often referred to the Antarctic interior as a "high, white desert" in their journals. While early 20th-century readers found the juxtaposition of ice and desert poetic or paradoxical, meteorologists eventually codified this reality. Today, the Antarctic Desert is recognized as the largest desert on Earth, spanning approximately 14.2 million square kilometers, with the Arctic Desert ranking as the second largest.