The Atacama Desert (Spanish: Desierto de Atacama) is a desert plateau located on the Pacific coast of South America, in the north of Chile. Stretching over a 1,600-kilometre-long (1,000-mile) strip of land west of the Andes Mountains, it covers an area of 105,000 km2 (41,000 sq mi),[2] which increases to 128,000 km2 (49,000 sq mi) if the barren lower slopes of the Andes are included.[3]
The Atacama Desert is the driest nonpolar desert in the world, and the second driest overall, behind some specific spots within the McMurdo Dry Valleys.[4][5][6][7] It is the only true desert to receive less precipitation than polar deserts, and the largest fog desert in the world. The area has been used as an experimentation site for Mars expedition simulations due to its similarities to the Martian environment.
The constant temperature inversion caused by the cool north-flowing Humboldt ocean current and the strong Pacific anticyclone contribute to the extreme aridity of the desert.[8] The most arid region of the Atacama Desert is situated between two mountain chains, the Andes and the Chilean Coast Range, which are high enough to prevent moisture advection from either the Pacific or the Atlantic Ocean, creating a two-sided rain shadow effect.[9]
According to the World Wide Fund for Nature, the Atacama Desert ecoregion occupies a continuous strip for nearly 1,600 kilometres (1,000 mi) along the narrow coast of the northern third of Chile, from near Arica (18°24′S) southward to near La Serena (29°55′S).[10] The National Geographic Society considers the coastal area of southern Peru to be part of the Atacama Desert[11][12] and includes the deserts south of the Ica Region in Peru. However, other sources consider that the part of the desert in Peru is a different ecosystem, and should properly be named as Pampas de la Joya desert.
Peru borders it on the north and the Chilean Matorral ecoregion borders it on the south.To the east lies the less arid Central Andean dry Puna ecoregion. [citation needed]The drier portion of this ecoregion is located south of the Loa River between the parallel Sierra Vicuña Mackenna and the Cordillera Domeyko.[citation needed] To the north of the Loa lies the Pampa del Tamarugal.[citation needed]
The Coastal Cliff of northern Chile west of the Chilean Coast Range is the main topographical feature of the coast.[13] The geomorphology of the Atacama Desert has been characterized as a low-relief bench "similar to a giant uplifted terrace" by Armijo and co-workers.[14] The intermediate depression (or Central Valley) forms a series of endorheic basins in much of the Atacama Desert south of latitude 19°30'S. North of this latitude, the intermediate depression drains into the Pacific Ocean.[15]
In December 2023, scientists, for the first time, reported on a recently discovered area in the territory of Puna de Atacama, which may have similarities to Earth during the Archean eon and thus to the environment of the first life forms on Earth. It could as well be similar to conceivably-hospitable conditions on the planet Mars during earlier Martian times.[16]