24 percent of the land in the Northern Hemisphere has permafrost underneath it (Figure 1). Permafrost exists where the ground stays at or below 0° Celsius (32° Fahrenheit) for at least two years in a row. So, seasonally frozen ground makes up about 55 million square kilometers (21 million square miles). 58 percent of the land in the Northern Hemisphere freezes seasonally. Seasonally frozen ground freezes and thaws every year. Where is frozen ground in the Northern Hemisphere? Yet more than half of the land in the Northern Hemisphere freezes and thaws at some point during the year. People may not stop to think about how the ground changes where they live, and whether or not it ever freezes for all or part of the year.
Many people have not ever really thought about the ground under their feet. Circumpolar Active-Layer Permafrost System (CAPS), version 1.0. Lighter purples, and the terms isolated and sporadic, refer to lower percentages of frozen ground.Ĭredit: Map by Philippe Rekacewicz, UNEP/GRID-Arendal data from International Permafrost Association, 1998.
On this map, darker shades of purple indicate larger percentages of permanently frozen ground. A large portion of the Arctic has permafrost.
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