Polar deserts are areas with annual precipitation less than 250 mm and a mean
temperature during the warmest month of less than 10° C.
Polar deserts on the Earth cover nearly 5 million square kilometers and are
mostly bedrock or gravel plains.
Source: Death Valley
Source: Um Maine
To read about this term in context:
GreenFacts Summary on Arctic Climate Change:
Español: Desierto polar
Français: Désert polaire