Some Recent Advances and Future Directions in Permafrost Research

The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Field-based studies, remote sensing and modeling are revealing complex feedbacks of permafrost degradation to terrestrial and offshore environments in Polar Regions and the Earth’s atmosphere. Major research questions that remain to be adequately answered involve uncertainties about the vulnerability of permafrost to thaw, a projected decline in permafrost extent during the coming decades, ecosystem feedbacks, and the global consequences to climate change of mobilizing ancient carbon from permafrost as it thaws. Some of these important questions are: How resilient is permafrost to climate change and external disturbance, and what are the feedbacks to permafrost stability? How will permafrost degradation and landform changes alter hydrology and ecosystems? How large are carbon pools in and beneath permafrost including subsea permafrost, how vulnerable are they to disturbance related to degradation of permafrost, and to what extent will altered carbon and energy cycles affect the global climate? Ground temperatures are a primary indicator of permafrost stability. The monitoring network of the Thermal State of Permafrost (TSP) program under the Fourth International Polar Year (IPY) has more than 550 sites across the circumpolar region. TSP measurements, combined with numerical thermal modeling, now provide a relatively comprehensive assessment of panarctic permafrost dynamics during the last ~100 years. However, current numerical models project the future state of permafrost largely based on subsurface thermal dynamics driven by regional or global climate model projections and internal surface and ground properties. These models largely ignore complicated sub-grid scale feedbacks associated with dynamic ecological components and disturbance. Disturbances of the ground thermal regime can be triggered by fires, floods, and vegetation and soil removal that can result in rapid local degradation of permafrost by thermokarst or thermo-erosion involving both vertical and lateral thaw. Though local in nature, disturbance processes are widespread in permafrost regions and their occurrence and magnitude are likely to increase with climate warming in the Arctic. Permafrost research is becoming increasingly interdisciplinary, involving geophysicists, hydrologists, terrestrial and aquatic ecologists, geochemists, geologists, engineers, modelers, and sociologists. During IPY, large, integrated projects such as the TSP, Carbon Pools in Permafrost (CAPP), and Arctic Circumpolar Coastal Observatory Network (ACCO-Net) have sought to better understand permafrost and the impacts of its degradation at high latitudes. Despite our accumulating knowledge of changing permafrost conditions during Quaternary climate cycles, the extensive presence of thermokarst in northern regions, and the large carbon pools in permafrost that can feedback to climate change, future permafrost dynamics and its impacts remain poorly quantified on the panarctic scale. To make progress, disciplines must team together to understand the patterns, processes, and consequences of permafrost thaw to the earth system.