Atacama Desert
| Atacama Desert | |
|---|---|
 Atacama by NASA World Wind | |
 Map of the Atacama Desert: the area most commonly defined as Atacama is in yellow. In orange are the outlying arid areas of the southern Chala, Altiplano, Puna de Atacama, and Norte Chico. The vertical extent of the satellite photo is approximately 2,600 km, encompassing the desert and surrounding regions. | |
| Ecology | |
| Realm | Neotropical |
| Biome | Deserts and xeric shrublands |
| Borders | |
| Geography | |
| Area | 104,741 km2 (40,441 mi2) |
| Country | Chile |
| Coordinates | 24°30′S 69°15′W / 24.500°S 69.250°W |
| Conservation | |
| Protected | 3,385 km² (3%)[1] |
The Atacama Desert (Spanish: Desierto de Atacama [ataˈkama]) is a desert plateau on the Pacific coast of South America, stretching along a 1,600-kilometre-long (1,000-mile) strip of land in northern Chile, west of the Andes. It covers an area of 105,000 km2 (41,000 mi2),[2] rising to 128,000 km2 (49,000 mi2) if the barren lower slopes of the Andes are included.[3]
The Atacama is the driest non-polar desert in the world and the largest fog desert on Earth.[4] Extreme aridity results from its position between two mountain chains—the Andes and the Chilean Coast Range—of sufficient height to block moisture from both the Pacific and Atlantic oceans, creating a two-sided rain shadow.[5] The cool, north-flowing Humboldt Current and the South Pacific anticyclone reinforce this effect.[6] Average annual rainfall is around 15 mm (0.6 in) per year,[7] and some weather stations in the desert have never recorded rain. Evidence suggests the desert may have received no significant rainfall from 1570 to 1971,[2] and hyper-arid conditions date back at least to the Miocene.[8] As of September 2026, there are new doubts regarding the continuity of Atacama desert's hyperaridity, following a publication by Gutstein et al. regarding semiaquatic fossil finds in northern Chile, dated 8.8 Ma.[9]
The desert borders Peru to the north and the Chilean Matorral ecoregion to the south, with the less arid Central Andean dry puna to the east. Its high altitude, dry air, and near-total absence of light pollution make it one of the world's premier sites for astronomical observation, hosting several major observatories including the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope.[10] Its soil composition and near-total absence of microbial life have also made it a testing ground for Mars mission instruments.[11]
The desert has been inhabited since at least 7000 BCE, when the Chinchorro culture settled along its coast. Later peoples included the Atacameño and, during the Inca Empire, Aymara communities. Under Spanish colonial rule, coastal towns developed as ports for silver exports; in the 19th century, rich deposits of sodium nitrate made the region a zone of conflict between Chile, Bolivia, and Peru, culminating in the War of the Pacific.[12] Today the desert is sparsely populated, with tourism, copper mining, and astronomical research as its principal industries.
Setting
[edit]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).[13] The National Geographic Society considers the coastal area of southern Peru to be part of the Atacama Desert[14][15] 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.[16] 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.[17] 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.[18]
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 also be similar to conceivably-hospitable conditions on the planet Mars during earlier Martian times.[19]
Climate
[edit]
The Atacama has a cold desert climate (in the Köppen climate classification, BWk) with generally mild temperatures year-round and only slight temperature differences across seasons. Rather than the intense heat of many other deserts around the world, the almost total lack of precipitation is the most prominent characteristic of the Atacama Desert.[21]
Aridity
[edit]
The Atacama Desert is commonly known as the driest place in the world, especially the surroundings of the abandoned Yungay mining town, where the University of Antofagasta Desert Research Station is located,[22][11] in Antofagasta Region, Chile.[23] The average rainfall is about 15 mm (0.6 in) per year,[7] although some locations receive only 1 to 3 mm (0.04 to 0.12 in) in a year.[24] Moreover, some weather stations in the Atacama have never received rain. Periods up to four years have been registered with no rainfall in the central sector, delimited by the cities of Antofagasta, Calama and Copiapó.[25] Evidence suggests that the Atacama may not have had any significant rainfall from 1570 to 1971.[2]
.JPG)
The Atacama Desert may be the oldest desert on earth, and has experienced hyper aridity since at least the Middle Miocene, since the establishment of a proto-Humboldt current in conjunction with the opening of the Tasmania-Antarctic passage ca. 33 million years ago (Ma).[8] The opening of the Tasmania-Antarctic passage allowed for cold currents to move along the west coast of South America, which influenced the availability of warm humid air to travel from the Amazon Basin to the Atacama. Though there was a general lack of humid air after 33 Ma, there were punctuated intervals of increased humidity,[26] such as between around 10.86 and 6.4 Ma, when the Tiliviche Palaeolake existed before turning into a salar sometime before the Middle Pliocene.[27] The long history of aridity raises the possibility that supergene mineralisation, under the appropriate conditions, can form in arid environments, instead of requiring humid conditions.[28] The presence of evaporite formations suggests that in some sections of the Atacama Desert, arid conditions have persisted for the last 200 million years (since the Triassic).
Aridity in Atacama Desert predates the rise of the Central Andes, yet hyper-aridity is generally thought to have resulted from the rise of the Andes.[29] As such it is hypothesised it had climatic conditions akin to the Namib Desert prior to the rise of the mountains.[29]
The Atacama is so arid that many mountains higher than 6,000 m (20,000 ft) are completely free of glaciers. Only the highest peaks (such as Ojos del Salado, Monte Pissis, and – debatably[30][31][32][33][34] – Llullaillaco) have some permanent snow coverage.
The southern part of the desert, between 25° and 27°S, may have been glacier-free throughout the Quaternary (including during glaciations), though permafrost extends down to an altitude of 4,400 m (14,400 ft) and is continuous above 5,600 m (18,400 ft). Studies by a group of British scientists have suggested that some river beds have been dry for 120,000 years.[35] However, some locations in the Atacama receive a marine fog known locally as the camanchaca, providing sufficient moisture for hypolithic algae, lichens, and even some cacti—the genus Copiapoa is notable among these.
Geographically, the aridity of the Atacama is explained by its being situated between two mountain chains (the Andes and the Chilean Coast Range) of sufficient height to prevent moisture advection from either the Pacific or the Atlantic Oceans, a two-sided rain shadow.[5]
Despite modern views of the Atacama Desert as fully devoid of vegetation, in pre-Columbian and colonial times a large flatland area there known as Pampa del Tamarugal was a woodland, but demand for firewood associated with silver and saltpeter mining in the 18th and 19th centuries resulted in widespread deforestation.[36][A]
A recent find of a Late Miocene capybara (Cardiatherium) fossil and associated palm tree phytoliths in northern Chile casts doubts on the currently accepted view of the historical weather conditions in the Atacama desert. The presence of a semiaquatic fossil, dating back to approximately 8.8 Ma, indicates that at that time, Atacama desert possessed a significantly wetter climate characterized by freshwater rivers, coastal wetlands, and palm tree canopies. According to an upcoming publication by Gutstein et al.,[9] the finds introduce a critical nuance to hyperarid paleoclimatology, proving that the Atacama's long-term aridity was punctuated by prolonged, ecologically rich humid intervals capable of supporting diverse megafauna.[9][37][38]
Comparison to Mars
[edit]
In a region about 100 km (60 mi) south of Antofagasta, which averages 3,000 m (10,000 ft) in elevation, the soil has been compared to that of Mars. Owing to its otherworldly appearance, the Atacama has been used as a location for filming Mars scenes, most notably in the 2004 television series Space Odyssey: Voyage to the Planets.
In 2003, a team of researchers published a report in which they duplicated the tests used by the Viking 1 and Viking 2 Mars landers to detect life and were unable to detect any signs in Atacama Desert soil in the region of Yungay.[11] The region may be unique on Earth in this regard and is being used by NASA to test instruments for future Mars missions. The team duplicated the Viking tests in Mars-like Earth environments and found that they missed present signs of life in soil samples from Antarctic dry valleys, the Atacama Desert of Chile and Peru, and other locales. However, in 2014, a new hyperarid site was reported, María Elena South, which was much drier than Yungay and, thus, a better Mars-like environment.[40]
Towards Atacama, near the deserted coast, you see a land without men, where there is not a bird, not a beast, nor a tree, nor any vegetation.
In 2008, the Phoenix Mars Lander detected perchlorates on the surface of Mars at the same site where water was first discovered.[42] Perchlorates are also found in the Atacama and associated nitrate deposits have contained organics, leading to speculation that signs of life on Mars are not incompatible with perchlorates. The Atacama is also a testing site for the NASA-funded Earth–Mars Cave Detection Program.[43]
On 21 February 2023, scientists reported the findings of a "dark microbiome" of unfamiliar microorganisms in the Atacama Desert.[44][45]
Extreme weather events
[edit]In June 1991, Antofagasta and Taltal and inland regions as far as Calama received unusual rainfall leading to formation of a series of mudflows that killed 91 people.[46][47][48]
In 2012, the altiplano winter brought floods to San Pedro de Atacama.[49][50]
On 25 March 2015, heavy rainfall affected the southern part of the Atacama Desert.[51][52] Resulting floods triggered mudflows that affected the cities of Copiapo, Tierra Amarilla, Chanaral and Diego de Almagro, causing the deaths of more than 100 people.
In early 2019, extreme heat and wildfires in Chile resulted in heavy flooding in the Atacama.[53] At least 6 people died and 346 homes were destroyed.[54][55]
Flora
[edit]
In spite of the geographic and climatic conditions of the desert, a rich variety of flora has evolved there. Over 500 species have been gathered within the border of this desert. These species are characterized by their extraordinary ability to adapt to this extreme environment.[56] The most common species are herbs and flowers such as thyme, llareta, and saltgrass, and where humidity is sufficient, trees such as the tamarugo (endemic to the atacama), the chañar, the pimiento tree and the leafy algarrobo.
The llareta is one of the highest-growing wood species in the world. It is found at altitudes between 3,000 and 5,000 m (9,800 and 16,400 ft). Its dense form is similar to a pillow some 3 to 4 m (9.8 to 13.1 ft) thick. It concentrates and retains the heat from the day to cope with low evening temperatures. The growth rate of the llareta has been recently estimated at 1.5 cm/year (0.59 in/year), making many llaretas over 3,000 years old. It produces a much-prized resin, which the mining industry once harvested indiscriminately as fuel, making this plant endangered.
The desert is also home to cacti, succulents, and other plants that thrive in a dry climate. Cactus species here include the candelabro and cardon, which can reach a height of 7 m (23 ft) and a diameter of 70 cm (28 in).
The Atacama Desert flowering (Spanish: desierto florido) can be seen from September to November in years with sufficient precipitation, as happened in 2015.[51][52]
Fauna
[edit]
The climate of the Atacama Desert limits the number of animals living permanently in this extreme ecosystem. Some parts of the desert are so arid, no plant or animal life can survive. Outside of these extreme areas, sand-colored grasshoppers blend with pebbles on the desert floor, and beetles and their larvae provide a valuable food source in the lomas (hills). Desert wasps and butterflies can be found during the warm and humid season, especially on the lomas. Red scorpions also live in the desert.
A unique environment is provided by some lomas, where the fog from the ocean provides enough moisture for seasonal plants and a few animal species. Surprisingly few reptile species inhabit the desert and even fewer amphibian species. The