What Are the World's Major Deserts? Climate, Landscape, and Life

What Is a Desert?

A desert is defined not by heat or sand but by lack of precipitation. Any region that receives less than 250 millimeters (10 inches) of precipitation per year is classified as a desert. By this definition, deserts cover approximately 33% of Earth's land surface and exist on every continent — including Antarctica.

The popular image of a desert — a sea of golden sand dunes — represents only about 20–25% of desert area worldwide. In reality, most desert surfaces are rocky (reg), gravelly (serir), or mountainous. Sandy deserts are known as ergs in Arabic.

Types of Deserts

Hot and Dry Deserts

What most people picture: high temperatures year-round, little rainfall, intense solar radiation, and dramatic temperature swings between day and night. Located in subtropical bands (around 30° north and south latitude) where descending dry air suppresses precipitation. Examples: Sahara, Arabian Desert, Great Victorian Desert of Australia.

Cold Deserts

Cold year-round or with cold winters. Still receive very little precipitation, often because they are located in the rain shadow of mountain ranges or at polar latitudes. Examples: Gobi Desert (Asia), Patagonian Desert (South America), Great Basin (USA).

Polar Deserts

Antarctica and the Arctic receive little precipitation (mostly snowfall) and qualify as deserts by definition. Antarctica is the world's largest and driest desert — the Atacama and Sahara pale in comparison to its aridity in the interior.

Coastal Deserts

Found along some coastlines where cold ocean currents chill and stabilize the air, preventing it from rising and forming rain clouds. The Atacama (South America's Pacific coast) and Namib (southern Africa's Atlantic coast) are created by the Humboldt and Benguela currents respectively.

The World's Major Deserts

Antarctic Desert

Area: ~14.2 million km² — the world's largest desert. Antarctica receives less than 200 mm of precipitation per year in coastal areas and far less in the interior. Temperatures can fall below -80°C (-112°F). Despite being a frozen desert, Antarctica contains about 70% of the world's fresh water in its ice sheets.

Arctic Desert

Area: ~13.9 million km² — comparable in size to Antarctica. Covers the Arctic Ocean ice and portions of Canada, Greenland, Russia, and other high-latitude landmasses. Receives very little precipitation due to cold, dry air masses.

Sahara Desert

Area: ~9.2 million km² — the world's largest hot desert, covering most of North Africa. The name comes from the Arabic word for "desert." The Sahara experiences extreme temperature ranges: daytime summer temperatures can exceed 50°C (122°F), while temperatures can drop below freezing at night. It has not always been desert — "Green Sahara" periods during the Holocene (roughly 11,000–5,000 years ago) featured lakes, grasslands, and hippos where there is now sand and rock.

Arabian Desert

Area: ~2.3 million km² — covers most of the Arabian Peninsula including Saudi Arabia, Yemen, Oman, UAE, Kuwait, Qatar, and Bahrain. Contains the Rub' al Khali (Empty Quarter) — the world's largest continuous sand desert, covering 650,000 km². Also sits atop the world's largest oil reserves — ancient organic matter from prehistoric seas.

Gobi Desert

Area: ~1.3 million km² — spans northern China and southern Mongolia. A cold desert formed largely in the rain shadow of the Himalayas and Tibetan Plateau, which block moisture from the Indian Ocean. The Gobi is famous for its dinosaur fossils — it was the stomping ground of species like Protoceratops and Velociraptor. Temperatures range from -40°C in winter to 45°C in summer.

Patagonian Desert

Area: ~673,000 km² — South America's largest desert, in Argentina east of the Andes. A cold desert formed in the rain shadow of the Andes, which block Pacific Ocean moisture. Home to guanacos, rheas, Patagonian maras, and armadillos.

Atacama Desert

Area: ~181,000 km² — Chile and Peru. The world's driest non-polar desert — some areas have received no measurable rainfall for centuries. Created by the cold Humboldt Current and the double rain shadow of the Andes and Chilean coastal range. Despite its extreme aridity, astronomers prize the Atacama for its exceptional clarity — the world's largest telescope arrays are located there.

Life in Deserts

Deserts support remarkable biodiversity through extraordinary adaptations:

• Plants: Cacti store water in succulent tissues; deep-rooted desert shrubs access groundwater; ephemeral plants complete their entire life cycle in days after rare rainfall.
• Animals: Many are nocturnal, avoiding the heat of the day. The fennec fox has enormous ears for radiating heat. Camels store energy (not water) in their humps and can lose 25% of body weight in water without harm. Kangaroo rats never drink water, obtaining all they need from their food.
• People: Desert civilizations developed along rivers (Egypt on the Nile), at oases, or through nomadic patterns. Bedouin, Tuareg, and Australian Aboriginal peoples developed sophisticated knowledge of desert environments over millennia.

Desertification: When Deserts Expand

Desertification is the process by which formerly productive land becomes desert, typically through a combination of climate change, drought, and human activities (overgrazing, deforestation, intensive agriculture). The Sahel region south of the Sahara is one of the world's most vulnerable areas, where advancing desertification threatens the livelihoods of millions.

The Great Green Wall initiative — a pan-African effort to restore vegetation in an 8,000 km belt across Africa from Senegal to Djibouti — aims to halt Saharan expansion while creating jobs and food security.