Permafrost Facts Land Coverage 25% of Earth's surface Max. Depths 3000 to 5000 feet (Siberia) Location Polar, subpolar, & alpine regions Countries with over 50% coverage Russia, Canada (also Antarc.) Typical Arctic soil temps 9°F to 23°F Did you know? Agriculture, mining, water supply, sewage disposal, and construction are all seriously affected by the expansion and contraction of permafrost soils caused by cycles of freezing and thawing. The "active layer" of permafrost is the upper layer of soil that thaws during the summer months, in places reaching several feet in depth. The International Permafrost Conference held in Yellowknife, Canada in June of 1998, included 188 papers by 368 authors from 19 countries. Permafrost underlies much of the Arctic tundra regions; poor soil drainage through the frozen ground results in an abundance of ponds, bogs, and streams.

Permafrost Studies

Permafrost is defined as any rock or soil remaining at or below freezing temperature for two or more years. It is not determined by soil moisture content, overlying snow cover, or location; in fact, permafrost can contain over 30 percent ice, or practically no ice at all. Along the northern coasts of the Arctic ocean permafrost even reaches out under the seabed of the shallow shelf seas. It can also be found on many alpine peaks in the tropics.

Permafrost occurs in more than 50% of Russia and Canada, 82% of Alaska, 20% of China, and probably all of Antarctica. Permafrost on land is more widespread and extends to greater soil depths in the Arctic than in subarctic regions. The permafrost is 5,250 feet thick in northern Siberia and 2,100 feet thick in northern Alaska, and it thins progressively toward the south. Permafrost in the Northern Hemisphere is generally differentiated on land into two broad zones--continuous (tundra regions) and discontinuous (alpine regions). At a depth of about 30 to 50 feet, the temperature of permafrost varies from near the freezing mark at its southern limit to 14° F in northern Alaska and 9° F in northeastern Siberia.

Understanding permafrost is not only important to civil engineering and architecture, it's also a crucial part of studying global change and protecting sensitive ecosystems in cold regions. Many research projects have focused on construction problems resulting from freezing and thawing of permafrost layers and poor soil drainage. Civil engineers must possess a thorough understanding of the thermal and mechanical problems unique to permafrost if they are to design passable roads, usable air strips, safe buildings, and reliable pipelines in far northern areas. In addition, soil scientists and climatologists bore holes into the permafrost to analyze sample soil compositions and to monitor climate changes. Geologists and geocryologists have been mapping permafrost distribution for at least 50 years.

Of significant importance today, scientists have come to recognize the crucial role permafrost plays in the storage and release of carbon, a major factor in future global change. Ongoing research has revolved around the impacts of global warming on the permafrost layers and the problems associated with permafrost loss for local communities and for future resource development projects.