Greenland is defined by ice, yet scientifically, large portions of the island, particularly the vast interior, are classified as a desert environment. This seeming contradiction stems from a common misunderstanding about what defines an arid landscape. To understand how a place covered by miles of ice can be a desert, one must look beyond temperature and focus on the scarcity of moisture supply.
The Definitive Criteria for Desert Classification
The scientific classification of a desert hinges on aridity, which measures the lack of effective moisture. This classification is not based on temperature, meaning a desert can be hot or extremely cold. A common metric defines a region as a desert if it receives less than 250 millimeters (about 10 inches) of precipitation annually.
More complex systems, like the Köppen climate classification, compare total precipitation to the rate of potential evapotranspiration. This aridity index acknowledges that hot regions require more rainfall to avoid desert status because heat causes moisture to evaporate quickly. Therefore, a cold region can qualify as a desert with very little precipitation since moisture loss through evaporation is minimal. The defining factor is the lack of moisture falling, not the presence of heat.
Greenland’s Low Precipitation Reality
Applying these criteria shows that Greenland’s interior falls into the desert category due to its extremely low annual precipitation. While the southern and southeastern coastal areas receive significant moisture (sometimes exceeding 1,900 millimeters), the interior is strikingly dry. The central ice sheet is so far inland and high in elevation that it is starved of moisture from the sea.
The vast majority of the interior receives less than the 250-millimeter desert threshold, with some regions recording as little as 50 millimeters (about 2 inches) of precipitation each year. This minimal moisture falls as fine, dry snow. The persistent cold causes the atmosphere over the ice sheet to hold very little water vapor, contributing to the overall aridity of the environment.
The Polar Desert Distinction and the Ice Sheet
The classification applied to the large arid areas of Greenland is specifically the “polar desert” distinction. Polar deserts are characterized by low annual precipitation and mean temperatures that remain below 10 degrees Celsius (50 degrees Fahrenheit) in the warmest month. The apparent paradox of a desert covered in a massive ice sheet is resolved by understanding the balance between moisture gain and loss.
The Greenland Ice Sheet, which is up to 3,000 meters thick, exists not because of heavy snowfall, but because the minimal snowfall that occurs never melts. The ice mass is a fossilized accumulation of small annual snow layers gathered over hundreds of thousands of years. The process of ablation (melting and sublimation) is so low in the frigid interior that the small annual accumulation is preserved and compressed into ice. This continuous, low-level accumulation, maintained by extreme cold and low moisture loss, confirms the area’s arid status while accounting for the presence of the second-largest body of ice on Earth.