Permafrost
Water
Perennially frozen soil.
Weather
A layer of soil at varying depths below the surface in which the temperature has remained below freezing continuously from a few to several thousands of years.
Climate Change
Permafrost Layer of soil or rock, at some depth beneath the surface, in which the temperature has been continuously below 0 °C for at least some years. It exists where summer heating fails to reach the base of the layer of frozen ground.