The key role of forest disturbance in reconciling estimates of the northern carbon sink

We show that DGVMs simulate a 50% lower sink (1.1 ± 0.5 PgC yr −1 over 2001–2021) across North America, Europe, Russia, and China compared to atmospheric inversions (2.2 ± 0.6 PgC yr −1 ). We explain why DGVMs underestimate the carbon sink by considering how they represent disturbance processes, specifically the overestimation of fire emissions, and the lack of robust forest demography resulting in lower forest regrowth rates than observed.

We reconcile net sink estimates by using alternative disturbance-related fluxes. We estimate carbon uptake through forest regrowth by combining satellite-derived forest age and biomass maps. We calculate a regrowth flux of 1.1 ± 0.1 PgC yr −1 , and combine this with satellite-derived estimates of fire emissions (0.4 ± 0.1 PgC yr −1 ), land-use change emissions from bookkeeping models (0.9 ± 0.2 PgC yr −1 ), and the DGVM-estimated sink from CO 2 fertilisation, nitrogen deposition, and climate change (2.2 ± 0.9 PgC yr −1 ).