World's Dry Deserts: Global Distribution and Types

Dry deserts (arid lands with <250 mm annual precipitation) cover ~33% of Earth's land surface across five major regions:

North America

• Sonoran Desert: AZ, CA, MX — biseasonal rain, saguaro, highest biodiversity
• Mojave Desert: CA, NV, UT, AZ — Joshua trees, Death Valley (hottest), rain shadow
• Chihuahuan Desert: TX, NM, MX — largest North American desert, grassland-shrub transition
• Great Basin Desert: NV, UT, ID, OR — cold desert, sagebrush, internal drainage

South America

• Atacama Desert: Chile/Peru — world's driest non-polar (<1 mm/yr), fog-dependent life, lithium brine
• Patagonian Desert: Argentina — rain shadow of Andes, cold, windy, steppe
• Monte Desert: Argentina — rainshadow, shrublands

Africa

• Sahara: 9.2M km² — world's largest hot desert, ergs, hamadas, regs, oases
• Namib: Namibia/Angola — coastal fog desert, oldest (55-80 Ma), welwitschia
• Kalahari: Botswana/Namibia/RSA — semi-arid savanna, fossil dunes
• Danakil: Ethiopia/Eritrea/Djibouti — hottest average, salt flats, volcanism

Asia

• Gobi: Mongolia/China — cold desert, rain shadow, dinosaur fossils
• Taklamakan: China (Xinjiang) — shifting dunes, Silk Road, tarim basin
• Arabian Desert: Arabian Peninsula — Rub' al Khali (Empty Quarter), oil, hyper-arid
• Thar: India/Pakistan — monsoon margin, most populated desert

Australia

• Great Victoria: WA/SA — largest Australian desert
• Simpson: NT/SA/QLD — parallel dunes, red sand
• Great Sandy: WA — coastal transition, ironstone
• Gibson, Tanami, Little Sandy: Western/Central Australia

Polar Deserts

• Antarctic: 14M km² — largest desert, ice sheet, <50 mm precip
• Arctic: Northern Greenland, Canadian Archipelago, Svalbard — polar desert tundra

Formation Mechanisms

Subtropical highs (Hadley descent), rain shadows, cold currents, continentality, polar cooling — five engines, one outcome: evaporation ≫ precipitation.