Changing Arctic landscapes in a changing climate: thermokarst evolution in polygonal tundra

Abstract Ice wedges are ubiquitous features in high-latitude permafrost regions and are vulnerable to warming. Rapid changes in Arctic polygonal tundra landscapes due to melting of ice wedges, a process known as thermokarst, have significant impacts on infrastructure as well as hydrology. Despite the increased attention in recent field and modeling studies, models generally used for global climate predictions often lack the representation of thermokarst processes, leading to unreliable projections about the impact of warming on Arctic ecosystems. Here we use an integrated permafrost thermal hydrology model to simulate thermokarst evolution in six Arctic locations across a range of climates and landscapes using projected RCP8.5 climate scenario. Our model shows that widespread landscape changes will continue in the Arctic during the 21st century. These changes are likely to be more rapid (2–3 times) in warm and/or ice-rich permafrost than in cold and/or ice-poor permafrost regions. This suggests that local permafrost temperatures and ground ice will play a determining role in the future tundra landscape evolution. There is therefore a need to represent thermokarst processes in large-scale models to better understand how rising temperatures may alter Arctic tundra landscapes, which will have severe implications for its ecosystem.