A cold desert is a distinct type of arid ecosystem defined by low annual precipitation and consistently low temperatures. The defining characteristic is extreme aridity coupled with a prolonged, intense cold season, which dictates the unique biological and geological features of these regions. These environments are typically found far from oceanic moisture sources or at high elevations and latitudes, setting them apart from tropical and subtropical deserts.
Climatic Characteristics and Classification
Cold deserts are formally recognized within the Köppen climate classification system as BWk, or the cold arid subtype. The primary metric separating them from hot deserts is the mean annual temperature, which must be below 18°C (64.4°F) for a region to be classified as a cold desert. While summers can be warm, winters are characteristically long and dry, with temperatures often dropping far below freezing.
Aridity is marked by annual precipitation that is generally less than 25 centimeters (10 inches), often falling as snow or fog. A significant factor is the severe excess of potential evapotranspiration over actual precipitation. The low temperatures, however, result in lower overall evaporation rates compared to hot deserts, which helps conserve the scant available moisture. Polar deserts, such as large parts of the Arctic and Antarctica, are considered a subtype of cold desert, distinguished by having average summer temperatures below 10°C (50°F).
Geographical Location and Prominent Examples
The formation of cold deserts is linked to geographical and atmospheric processes that block the influx of moisture. Many of these arid lands are located in the interior of large continents, far from coastal influences, or situated in the rain shadow of massive mountain ranges. The rain shadow effect occurs when moist air is forced upward by a mountain, cooling and dropping precipitation on the windward side, leaving the leeward side exceptionally dry.
The Great Basin Desert in the western United States is made arid by the Sierra Nevada mountains. The Patagonian Desert in South America lies on the leeward side of the Andes, creating a massive, dry expanse in Argentina. The Gobi Desert, sprawling across China and Mongolia, is a classic example of a continental interior cold desert, resulting in extremely cold winters and significant seasonal temperature swings. High-altitude deserts, like the Ladakh region in the Himalayas, are also categorized as cold deserts, where elevation creates the extreme cold and limits atmospheric moisture.
Ecological Adaptations of Life
Life in cold deserts has developed specialized strategies to cope with the dual stresses of sub-zero temperatures and water scarcity. Plants in these challenging environments often exhibit xerophytic adaptations, focusing on water conservation and efficient uptake. Low-lying, drought-resistant shrubs, such as sagebrush in North America, possess extensive, deep root systems to access groundwater and small, waxy leaves to minimize water loss through transpiration.
Animals also employ behavioral and physiological mechanisms to survive the frigid, dry conditions. Many small mammals, including various rodents, burrow underground where temperatures are more stable and humidity is higher. Larger mammals, like the Bactrian camel, feature thick coats for insulation and possess the capacity to endure long periods without drinking water. Furthermore, many fauna have highly efficient kidneys, which produce extremely concentrated urine to minimize the loss of body water.