A desert is not a place without life, or even necessarily without water — it is a place where more water evaporates than falls. That simple balance produces a third of the world's land surface, including the largest desert of all: Antarctica.
Play the Deserts quiz33%
Of Earth's land
14.2M km²
≈ 5.48M mi²
Largest (Antarctic)
56.7°C
≈ 134.1 °F
Highest recorded
<250 mm
≈ 9.84 in
Typical annual rain
The five kinds of desert
Deserts are classified by what takes the moisture away.
Subtropical
Dry air sinking under the global circulation cells — the Sahara, Arabian, Kalahari and Australian deserts.
Coastal
Cold ocean currents chill the air above them so it cannot rain — the Atacama, Namib and Baja.
Rain shadow
Mountains wring out the moisture first — the Great Basin, Patagonia and the Gobi.
Interior continental
Distance from any ocean leaves the air dry — the Taklamakan and the Karakum.
Polar
Cold air holds almost no water vapour — Antarctica, the Arctic and much of Greenland.
The largest deserts
Ranked by area. Two of the top three are frozen.
Antarctic Desert
Coldest, windiest, driest continent; parts of it have not seen rain in two million years.
14.2M km²
≈ 5.48M mi²
Arctic Desert
Sea ice and polar tundra across northern Canada, Russia, Greenland and Alaska.
13.9M km²
≈ 5.37M mi²
Sahara
The largest hot desert, roughly the size of the United States, expanding and shrinking on a 20,000-year cycle.
9.2M km²
≈ 3.55M mi²
Arabian Desert
Empty Quarter dunes reach 250 m (820.2 ft); summer highs regularly pass 50°C (122 °F).
2.3M km²
≈ 0.89M mi²
Gobi
A cold desert of gravel plains whose dust storms reach Beijing and beyond.
1.3M km²
≈ 0.5M mi²
Kalahari
Semi-arid sandveld across Botswana, Namibia and South Africa, home to the San peoples.
0.9M km²
≈ 0.35M mi²
Life on very little water
Desert species are specialists, not survivors by luck.
Welwitschia
A Namib plant with just two leaves that can live over 1,000 years by harvesting coastal fog.
Camel humps
Store fat, not water — burning fat releases both energy and moisture when it matters.
Atacama's dry spell
Some weather stations in northern Chile have recorded no measurable rain for decades.
Desertification
Around a fifth of dryland is degrading through overgrazing, deforestation and drought, affecting billions of people.
Did you know?
- The Atacama is the driest non-polar desert; its rain-shadow position and cold offshore current keep it almost rainless.
- Sahara dust blows across the Atlantic and fertilises the Amazon basin — around 27 million tonnes of it a year.
- Desert nights can be freezing: without humidity to trap heat, temperatures can fall 30°C (86 °F) after sunset.
- The Sahara was green 6,000 years ago, with lakes, hippos and human settlements across what is now sand.