Permafrost, or perenially frozen ground, is a critical component of the cryosphere and the Arctic
system. Permafrost regions occupy approximately 24% of the terrestrial surface of the Northern Hemisphere; further, the distribution of subsea permafrost in the Arctic Ocean is not well known, but new
occurrences continue to be found. The effects of climatic warming on permafrost and the seasonally
thawed layer above it (the active layer) can severely disrupt ecosystems and human infrastructure such
as roads, bridges, buildings, utilities, pipelines, and airstrips. The susceptibility of engineering works to
thaw-induced damage is particularly relevant to communities and structures throughout northern Alaska,
Russia, and Canada. It is clear from the long-term paleographic record in these areas that climatic warming can lead to increases in permafrost temperature, thickening of the active layer, and a reduction in the
percentage of the terrestrial surface underlain by near-surface permafrost. Such changes can lead to
extensive settlement of the ground surface, with attendant damage to infrastructure.
To advance U.S. and international permafrost research, the U.S. Arctic Research Commission in 2002
chartered a task force on climate change, permafrost, and infrastructure impacts. The task force was
asked to identify key issues and research needs to foster a greater understanding of global change impacts
on permafrost in the Arctic and their linkages to natural and human systems. Permafrost was found to
play three key roles in the context of climatic changes: as a record keeper (temperature archive); as a
translator of climatic change (subsidence and related impacts); and as a facilitator of climatic change
(impact on the global carbon cycle). The potential for melting of ice-rich permafrost constitutes a significant environmental hazard in high-latitude regions. The task force found evidence of widespread warming of permafrost and observations of thawing —both conditions have serious, long-term implications for
Alaska’s transportation network, for the Trans-Alaska Pipeline, and for the nearly 100,000 Alaskan citzens living in areas of permafrost. Climate research and scenarios for the 21st century also indicate that
major settlements (such as Nome, Barrow, Inuvik, and Yakutsk) are located in regions of moderate or
high hazard potential for thawing permafrost. A renewed and robust research effort and a well-informed,
coordinated response to impacts of changing permafrost are the responsibilities of a host of U.S. federal
and state organizations. Well-planned, international polar research, such as the International Polar Year, is
urgently needed to address the key scientific questions of changing permafrost and its impacts on the
carbon cycle and overall global environment.
