Modeling the Effects of Climate Change on Permafrost in National Parks of Alaska: Will Permafrost Survive the Climate Warming of 21st Century?

Abstract:

Permafrost underlies ~70% of all National Park Service administered land in Alaska and it provides a stable foundation to parks’ ecosystems and wildlife habitats. However, the strength of this foundation is waning as its temperature is rising in response to recent climate warming. Consequently, thermokarst activities are on the rise and they are altering the parks’ landscape, ecosystems, and wildlife habitats. In order to effectively respond to these changes park managers need up-to-date knowledge of the current permafrost temperature and distribution, and how they might evolve with changing climate in the future. To help decision makers understand and respond to the changing permafrost condition, we are modeling near-surface permafrost dynamics—permafrost temperature, distribution, and active layer thickness—in eight national parks of Alaska at a decadal time scale. We are using GIPL 1.0 model (Spatially Distributed Model of Permafrost Dynamics in Alaska), the best available climate inputs, and high-resolution (28 m) ecotype, soil landscape, and snow inputs. Here we present results for two national parks—Denali National Park and Preserve (DENA) and Wrangell-St. Elias National Park and Preserve (WRST). Areas underlain by glaciers and permanent ice-fields were excluded. In DENA, the model suggested near-surface permafrost in 51% of the park area for the 2000 decade, predicted its decline to 6% by 2050s, and 1% by 2090s. In WRST, the model suggested near-surface permafrost in 72% of the park area for the 2000 decade, predicted its decline to 42% by 2050s, and 15% by 2090s. In summary, the near-surface permafrost will likely be degrading in most parts of DENA and WRST towards the end of the current century except at higher elevations where climate models continue to project colder temperature. The modeled maps of DENA and WRST showed 86% and 95% agreement with the field observations of permafrost presence/ absence at 1375 and 430 sites, respectively. In conclusion, the modeled high-resolution permafrost maps show the effect of changing climate on near-surface permafrost. They offer decision makers a clear understanding of how near-surface permafrost distribution in the parks might change in the future, which was lacking up until now, to guide critical monitoring and management decisions.