IPCC models omit abrupt permafrost thaw, leaving 1.5 trillion tons carbon unaccounted

Permafrost covers 15% of Northern Hemisphere land and stores 1.5 trillion tons of carbon, twice atmospheric levels. Thaw releases CO2 and methane via microbial decomposition, creating a feedback loop. Current policy in Alaska and Canada allows most wildfires to burn unless they threaten settlements, accelerating thaw in carbon-dense Yedoma deposits.

IPCC AR6 assessed permafrost carbon feedback but excluded abrupt collapse events documented in Woodwell Climate Research Center field data and Schuur et al. 2022 synthesis. Fire-driven emissions could reach 80 billion metric tons CO2 equivalent by 2100. Plant northward expansion offsets only a fraction of losses according to NASA Arctic-Boreal Vulnerability Experiment measurements.

Operational impact: emissions budgets and 1.5C pathways are underestimated without these terms. Mapping burn-risk and carbon-vulnerability layers in Alaska now identifies priority zones for early detection or prescribed burns, shifting from laissez-faire fire management to targeted intervention.

Next steps include incorporation of abrupt thaw modules into CMIP7 runs ahead of AR7, with Woodwell vulnerability maps scheduled for 2027 release to guide resource allocation.