Soil organic carbon pools in the northern circumpolar permafrost region

TLDR

The northern permafrost region covers ~18,782 × 10³ km², about 16 % of global soil area, and contains the highest mean soil organic carbon in peatlands and cryoturbated mineral soils (32.2–69.6 kg m⁻²). The study created the Northern Circumpolar Soil Carbon Database to estimate soil carbon pools, including deeper layers and previously unaccounted pools, in the northern permafrost region. Carbon pools were estimated from the database by integrating measurements up to 300 cm depth and deeper yedoma and deltaic deposits, extending beyond previous analyses. The estimated carbon pools were 191.29 Pg (0–30 cm), 495.80 Pg (0–100 cm), 1024.00 Pg (0–300 cm), with deeper yedoma and deltaic deposits adding 407 Pg and 241 Pg, respectively, yielding a total of 1672 Pg—about 88 % in frozen soils and roughly 50 % of global belowground organic carbon.

Abstract

The Northern Circumpolar Soil Carbon Database was developed in order to determine carbon pools in soils of the northern circumpolar permafrost region. The area of all soils in the northern permafrost region is approximately 18,782 × 10 3 km 2 , or approximately 16% of the global soil area. In the northern permafrost region, organic soils (peatlands) and cryoturbated permafrost‐affected mineral soils have the highest mean soil organic carbon contents (32.2–69.6 kg m −2 ). Here we report a new estimate of the carbon pools in soils of the northern permafrost region, including deeper layers and pools not accounted for in previous analyses. Carbon pools were estimated to be 191.29 Pg for the 0–30 cm depth, 495.80 Pg for the 0–100 cm depth, and 1024.00 Pg for the 0–300 cm depth. Our estimate for the first meter of soil alone is about double that reported for this region in previous analyses. Carbon pools in layers deeper than 300 cm were estimated to be 407 Pg in yedoma deposits and 241 Pg in deltaic deposits. In total, the northern permafrost region contains approximately 1672 Pg of organic carbon, of which approximately 1466 Pg, or 88%, occurs in perennially frozen soils and deposits. This 1672 Pg of organic carbon would account for approximately 50% of the estimated global belowground organic carbon pool.