Large amounts of soil carbon deposited in permafrost may be released into the atmosphere due to deeper seasonal thawing under the climatic conditions projected for the future. An increase in the volume of the available organic material together with the higher ground temperatures may lead to enhanced emission of greenhouse gasses.

Although in the public imagination the term “permafrost” is often associated with massive ice buried under the ground, it does not imply the presence of the frozen water. Frozen ground may be "dry"; the term "permafrost" refers to any sub-surface materials that remain below 0 °С for at least two consecutive years. Regions where permafrost underlies all or part of the ground surface occupy about 25 per cent of land area in the Northern Hemisphere, of which about 16.7 million km2 is located in north-eastern Eurasia and 10.2 million km2 in North America.

The mathematical formalism of all permafrost models is based on a solution of the Stefan problem. The peculiarity of the problem is the existence of the moving boundaries between the freezing and thawing ground which are the moisture phase change boundaries. The most perfect dynamic (process-based?динамические) models make it possible to calculate the consecutive temporal evolution of many permafrost parameters considering the thermal inertia of permafrost. However, usually it is impossible to realize the advantages of this kind of models for the large territories because of the limited data.

 

Several authors report that impacts of climate change on infrastructure in the Arctic are already evident. Damage to infrastructure and engineering structures in permafrost regions are often linked to observed increase in air temperature over the last 10 to 20 years. However, these reports do not show in detail how the change in air temperature may affect the active layer thickness and permafrost temperature at specific sites and for specific structures in the Arctic.

The permafrost regions currently occupy about one quarter of the Earth’s land area. Climate-change scenarios indicate that global warming will be amplified in the polar regions, and could lead to a large reduction in the geographic extent of permafrost. Development of natural resources, transportation networks, and human infrastructure in the high northern latitudes has been extensive during the second half of the twentieth century. In areas underlain by ice-rich permafrost, infrastructure could be damaged severely by thaw-induced settlement of the ground surface accompanying climate change.

The Circumpolar Active Layer Monitoring (CALM) program, established in the early 1990s, was designed to observe temporal and spatial variability of the active layer, near-surface permafrost parameters, and their response to changes and variations in climatic conditions. CALM is the world’s primary source of information about the active layer. Auxiliary information includes air temperature, soil moisture, soil temperature at different depth, snow cover, soil composition, and landscape characterization and frost heave and thaw subsidence.