Permafrost landscapes experience different disturbances and store large amounts of organic matter, which may become a source of greenhouse gases upon permafrost degradation. We analysed the influence of terrain and geomorphic disturbances (e.g. soil creep, active-layer detachment, gullying, thaw slumping, accumulation of fluvial deposits) on soil organic carbon (SOC) and total nitrogen (TN) storage using 11 permafrost cores from Herschel Island, western Canadian Arctic. Our results indicate a strong correlation between SOC storage and the topographic wetness index. Undisturbed sites stored the majority of SOC and TN in the upper 70cm of soil. Sites characterised by mass wasting showed significant SOC depletion and soil compaction, whereas sites characterised by the accumulation of peat and fluvial deposits store SOC and TN along the whole core. We upscaled SOC and TN to estimate total stocks using the ecological units determined from vegetation composition, slope angle and the geomorphic disturbance regime. The ecological units were delineated with a supervised classification based on RapidEye multispectral satellite imagery and slope angle. Mean SOC and TN storage for the uppermost 1m of soil on Herschel Island are 34.8kg C m(-2) and 3.4kgNm(-2), respectively. Copyright (c) 2015 John Wiley & Sons, Ltd.

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. Permafrost near the current southern margin of its extent is degrading, and this process may involve a northward shift in the southern boundary of permafrost by hundreds of kilometers throughout much of northern North America and Eurasia. A long-term increase in summer temperatures in the high northern latitudes could also result in significant increases in the thickness of the seasonally thawed layer above permafrost, with negative impacts on human infrastructure located on ice-rich terrain. Experiments involving general circulation model scenarios of global climate change, a mathematical solution for the thickness of the active layer, and digital representations of permafrost distribution and ice content indicates potential for severe disruption of human infrastructure in the permafrost regions in response to anthropogenic climate change. A series of hazard zonation maps depicts generalized patterns of susceptibility to thaw subsidence. Areas of greatest hazard potential include coastlines on the Arctic Ocean and parts of Alaska, Canada, and Siberia in which substantial development has occurred in recent decades.