Changes in Permafrost Landscapes Under Global Change

Abstract

Permafrost is susceptible to subtle changes in environmental conditions, including climate and surface disturbance. Relative to climate, land use is anticipated to be a more important component of global change in the coming decades. However, climate is anticipated to surpass land use as a factor later in the next century, particularly in the Arctic. Discussed here are the implications of land use and climate change in tundra ecosystems of the Yamal Region, Northwest Siberia. Since the discovery of super-giant natural gas fields in Yamal in the 1960’s, extensive exploration has resulted in the direct withdrawal of large areas for infrastructure development and associated disturbance regimes have led to cumulative impacts on thousands of additional hectares of land. The land withdrawals have pushed a relatively consistent or increasing number of reindeer onto progressively smaller parcels of pasture. This has led to excessive grazing and trampling of vegetation and, in many areas, erosion of sandy soils via deflation. The low arctic tundra lies entirely within the continuous permafrost zone and ice-rich substrates are widespread. One implication of this is that both anthropogenic and zoogenic disturbance regimes may easily initiate thermokarst and aeolian erosion, leading to significant further degradation of landscapes. Even without industrial disturbance, a slight change of the climate would result in massive thermokarst erosion. This would have negative consequences equal to or greater than the mechanical disturbances described above. The synergistic effects of land use coupled with climate change therefore have profound implications for the ecosystems of Yamal.