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The Sahara is often celebrated as the world’s iconic desert, stretching across nearly all of northern Africa and covering about 3.3 million square miles. Its name even translates to “desert” in Arabic, which reinforces the common perception that it is the planet’s biggest sandy expanse. In reality, it ranks third in size.
The largest deserts are found in the world’s polar regions. The Antarctic Polar Desert – encompassing the entire continent of Antarctica – spans roughly 5.5 million square miles and is officially the world’s biggest desert. The Arctic Polar Desert to the north covers 5.4 million square miles across parts of Russia, Alaska, Canada, and Scandinavia, making it the second largest.
Deserts are defined by their extreme dryness, receiving less than 10 inches of precipitation per year, rather than by temperature alone. While the Sahara, Arabian, and Mojave deserts are renowned for scorching heat, polar deserts also qualify under this definition, and they present some of the most extreme survival challenges on Earth.
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Antarctica contains 90 % of the planet’s freshwater, yet it remains the driest place on Earth. Its massive ice sheet, averaging 1.5 miles thick, traps the continent’s water in frozen form. The region receives only about two inches of precipitation annually – far less than the Sahara’s average – and temperatures can plunge to −128.2 °F, ensuring that any moisture that falls remains in solid ice.
Despite these harsh conditions, life persists. The emperor penguin, the largest penguin species, thrives in coastal areas with its dense feather plumage and substantial fat reserves that sustain it through the brutal winter months.
Further inland, where conditions intensify, lichen – a symbiotic partnership between algae and fungus – dominates the landscape. With no roots, lichens colonize substrates that would otherwise support no plant life, making them the most resilient organisms in the world’s largest and most barren desert.
