Large uncertainty in permafrost carbon stocks due to hillslope soil deposits

• Published in: Geophysical Research Letters
• Main Authors: Shelef, Eitan, Rowland, Joel C., Wilson, Cathy J., Hilley, G. E., Mishra, Umakant, Altmann, Garrett L., Ping, Chien -Lu
• Language: unknown
• Published: 2021
• Subjects: 58 GEOSCIENCES; Target Hill; permafrost; Alaska
• Online Access: http://www.osti.gov/servlets/purl/1389639; https://www.osti.gov/biblio/1389639; https://doi.org/10.1002/2017GL073823

Here, northern circumpolar permafrost soils contain more than a third of the global Soil Organic Carbon pool (SOC). The sensitivity of this carbon pool to a changing climate is a primary source of uncertainty in simulationbased climate projections. These projections, however, do not account for the accumulation of soil deposits at the base of hillslopes (hill-toes), and the influence of this accumulation on the distribution, sequestration, and decomposition of SOC in landscapes affected by permafrost. Here we combine topographic models with soil-profile data and topographic analysis to evaluate the quantity and uncertainty of SOC mass stored in perennially frozen hill-toe soil deposits. We show that in Alaska this SOC mass introduces an uncertainty that is > 200% than state-wide estimates of SOC stocks (77 PgC), and that a similarly large uncertainty may also pertain at a circumpolar scale. Soil sampling and geophysical-imaging efforts that target hill-toe deposits can help constrain this large uncertainty.