Abstract
As a contribution to the Regional Carbon Cycle Assessment and Processes phase 2 (RECCAP2) project, we present synthesized estimates of Arctic Ocean sea-air CO₂ fluxes and their uncertainties from surface ocean pCO₂-observation products, ocean biogeochemical hindcast and data assimilation models, and atmospheric inversions. For the period of 1985–2018, the Arctic Ocean was a net sink of CO₂ of 116 ± 4 TgC yr⁻¹ in the pCO₂ products, 92 ± 30 TgC yr⁻¹ in the models, and 91 ± 21 TgC yr⁻¹ in the atmospheric inversions. The CO2₂ uptake peaks in late summer and early autumn, and is low in winter when sea ice inhibits sea-air fluxes. The long-term mean CO₂ uptake in the Arctic Ocean is primarily caused by steady-state fluxes of natural carbon (70% ± 15%), and enhanced by the atmospheric CO₂ increase (19% ± 5%) and climate change (11% ± 18%). The annual mean CO₂ uptake increased from 1985 to 2018 at a rate of 31 ± 13 TgC yr⁻¹ dec⁻¹ in the pCO₂ products, 10 ± 4 TgC yr⁻¹ dec⁻¹ in the models, and 32 ± 16 TgC yr⁻¹ dec⁻¹ in the atmospheric inversions. Moreover, 77% ± 38% of the trend in the net CO₂ uptake over time is caused by climate change, primarily due to rapid sea ice loss in recent years. Furthermore, true uncertainties may be larger than the given ensemble standard deviations due to common structural biases across all individual estimates. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000642560Publication status
publishedExternal links
Journal / series
Global Biogeochemical CyclesVolume
Pages / Article No.
Publisher
American Geophysical UnionOrganisational unit
03731 - Gruber, Nicolas / Gruber, Nicolas
Funding
821003 - Climate-Carbon Interactions in the Coming Century (EC)
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