A regionalization approach to study vulnerability of Pan-Arctic permafrost carbon ctock to climate change

Background/Question/Methods

High latitude terrestrial ecosystems contain a large amount of soil organic carbon (SOC) in the frozen permafrost and hence are key components in the global carbon cycle. The increased thawing of permafrost due to climate warming, and the resulting microbial decomposition of the permafrost carbon pool is anticipated to be a significant positive feedback on future radiative forcing from terrestrial ecosystems to the Earth’s climate system. Improving understanding of permafrost carbon vulnerability and climate feedbacks is increasingly becoming a research priority. The current approach using permafrost regionalization map (PeRM) is a community effort within a collaborative network i.e. Vulnerability of Permafrost Carbon Research Coordination Network (RCN) aiming to characterize the northern permafrost domain based on key environmental characteristics among different geographies that we believe are important controls on either current soil organic matter (SOM) quantity or quality or future vulnerability of permafrost carbon. The map (PeRM) was developed based on the circum-arctic permafrost and ground ice condition map by Brown et al. (1997) and circum-arctic vegetation map developed by Walker et al. (2005). The permafrost regions were defined using different parameters including topography, geographical locations (continentality), types of permafrost present, types of biomes and arctic bioclimatic zones and predominant terrain types.

Results/Conclusions

Twenty one individually recognized and numbered regions were created as reporting regions within PeRM. The degree of subdivision for these regions was based on the basic evaluation of availability of data for each sub-region and the size of the carbon pool which also includes specific terrain types e,g, peatlands, yedoma and deltas with very high C storage. Basic analyses were performed to identify the representativeness and data gaps in the pan-arctic scale within the reporting regions of PeRM. The study site locations for circumpolar active layer monitoring (CALM) network, pan-arctic CH4 synthesis studies, pan-arctic incubation studies were done to show the representativeness of these studies. Climate analyses for all the reporting regions for four seasons showed increased temperature anomalies for both summer and fall during 2000s over 1990s. The PeRM will have many usages for the researchers within the RCN and beyond – including data synthesis, model-data integration and model benchmarking – to contribute to an improved understanding of the vulnerability of the permafrost carbon pool to climate change and the implications to the global carbon budget.