Major deserts of the world

Story hook

14th August 1971. A weather instrument at the village of Quillagua, Chile, in the Atacama Desert, records its 412th consecutive year of no measurable rainfall. Investigators later find rain gauges from the Spanish colonial era that suggest some Atacama valleys have not seen a drop of water since the time Columbus sailed. There are stretches of the Atacama where it is statistically more likely you will see a NASA Mars rover prototype (they test there) than rainfall in your lifetime.

Compare: an hour by plane east of the Atacama lies the Amazon, the rainiest place on Earth. The same Pacific coast that grows the lushness of Costa Rica turns into the driest non-polar desert in Chile within 30° of latitude. What separates them is one of the great teaching laws of geography — that deserts are not where it's hot, deserts are where the air sinks.

One-third of Earth's land surface is some form of desert or arid land. Deserts have shaped civilisations (Egypt would not exist without the Nile cutting through Sahara), trade (camel caravans across the Sahel + Silk Route through the Gobi), and modern energy geopolitics (half the world's oil reserves sit beneath the Arabian desert).

Why this matters for UPSC

Syllabus location: GS-I — World Physical Geography (major deserts). Asked 3-4 times in Prelims over the last decade — desert-country pairings, desert types, cold vs hot deserts. Mains uses deserts as case studies for desertification, climate change, water security. High-yield factual zone with map-based recall.