ALBERT

Description: Permafrost regions have been identified to host a soil organic carbon (C) pool of global importance, storing more than 1500 PgC. A large portion of this C pool is currently frozen in deep soils and permafrost deposits. Permafrost thaw hence may result in mobilization of large amounts of C as greenhouse gases, dissolved organic C, or particulate organic matter, with substantial impacts on C cycling and C pool distribution. Understanding potential consequences and feedbacks of permafrost degradation therefore requires better quantification of processes and landforms related to thaw. While many predictive land surface models so far consider a gradual increase in the average active layer thickness across the permafrost domain, rapid shifts in landscape topography and surface hydrology caused by thaw of ice-rich permafrost are much more difficult to project. Field studies of thermokarst and thermo-erosion indicate highly complex and rapid landscape-ecosystem feedbacks. Contrary to top-down permafrost thaw that may affect any permafrost type at the surface, both thermokarst and thermo-erosion are considered pulse disturbances that are closely linked to presence of near-surface ice-rich permafrost, are active on short sub-annual to decadal time scales, and may affect C stores tens of meters deep. Here we present a comprehensive review synthesizing measured and modeled rates of thermokarst and thermo-erosion processes from the scientific literature and own observations across the northern Hemisphere permafrost regions. The goal of our synthesis is (1) to provide an overview on the range of thermokarst and thermo-erosion rates that may be used for parameterization of thermokarst and thermo-erosion in ecosystem and landscape models; and (2) to assess simple back-of-the-envelope scenarios of the magnitude of C thaw due to thermokarst and thermo-erosion versus projected active layer thickening. Example scenarios considering thermokarst lake expansion and talik growth indicate that rapid thaw processes have a high possibility to contribute substantially to permafrost C mobilization over the coming century.

Description: Perennially frozen ground and sea ice are key constituents of permafrost coastal systems, and their presence is the primary difference between temperate and high-latitude coastal processes. These systems are some of the most rapidly changing landscapes on Earth and, in the Arctic, are representative of the challenges being faced at the intersection between natural and anthropogenic systems. Permafrost thaw, in combination with increasing sea level and decreasing sea-ice cover, exposes arctic coastal and nearshore areas to rapid environmental and social changes. Based on decadal timescales, observations in the Arctic indicate an increase in permafrost coastal bluff erosion and storm surge flooding of low-lying ice-rich permafrost terrain. However, circum-arctic observations remain limited and the factors responsible for the apparent increase in arctic coastal dynamics are poorly constrained. A better understanding of permafrost coastal systems and how they are responding to changes in the Arctic is important since a high proportion of Arctic residents live on or near coastlines, and many derive their livelihood from terrestrial and nearshore marine resources. An expanding industrial, scientific, and commercial presence in the Arctic Ocean will also require advanced knowledge about permafrost coastlines as terrestrial access points. Since the issues involved span political, cultural, geographical, and disciplinary borders, an international network focused on permafrost coastal systems in transition is needed. An integrative network focused on permafrost coastal systems is required to realize and address the scale and complexity of the processes, dynamics, and responses of this system to physical, ecological, and social change. A primary focus of such an effort would be guided by the fact that the issues and impacts associated with permafrost coastal systems in transition are far greater than any single institution or discipline is capable of addressing alone. Future permafrost coastal system dynamics will challenge conventional wisdom as the system enters a new state impacting human decision making and adaptation planning, cultural heritage resources and ecosystems, and likely resulting in unforeseen challenges across the Arctic.

Description: Permafrost degradation has already begun to cause damage to infrastructure across the Pan-Arctic and is increasing the potential for climate change related disasters for numerous Arctic nations. Permafrost degradation can pose a risk to the stability and function of Arctic infrastructure in three key ways: 1) where ground-ice is present, permafrost degradation will initiate thermokarst development causing the ground surface to subside, 2) in coastal regions permafrost degradation can increase the rate of coastal erosion and lead to more impactful storm surges, and 3) an increase in ground temperature can change the structural integrity and cohesiveness of the underlying ground surface leading to lateral and vertical ground movement, and a decrease in infrastructure foundation bearing capacity. In addition, recent infrastructure development and associated construction in northern regions has caused disturbance to the ground thermal regime. The combined effects of permafrost degradation from climate warming across the Arctic is likely to cause damage to and the loss of infrastructure critical to the function of Arctic industry and communities. As such, permafrost degradation-related disaster poses a major threat to national and international security across the Pan-Arctic. Successful preparation, response, recovery, and mitigation from permafrost-related disasters will require coordinated cross-border disaster diplomacy efforts and effective dissemination of findings. Critical to these efforts is the co-production of knowledge with indigenous communities and the development of cross-border research and monitoring networks that involve collaborators from a wide-range of backgrounds. We present several examples of such collaborative efforts including: an emerging international network of networks focused on better understanding permafrost affected coastal change across the pan-Arctic; the formation of transdisciplinary research teams involving scientists, stakeholders, community members, and policy makers, to prevent and mitigate permafrost-related disasters in northern communities; the development of a pan-Arctic long-term permafrost monitoring network; and the effective distribution of urgent permafrost research tasks across international multi-institutional teams.