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An assessment of CO2 uptake in the Arctic Ocean from 1985 to 2018
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  • Sayaka Yasunaka,
  • Manfredi Manizza,
  • Jens Terhaar,
  • Are Olsen,
  • Ryohei Yamaguchi,
  • Peter Landschützer,
  • Eiji Watanabe,
  • Dustin Carroll,
  • Hanani Adiwara,
  • Jens Daniel Müller,
  • Judith Hauck
Sayaka Yasunaka
Tohoku University

Corresponding Author:yasunaka@tohoku.ac.jp

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Manfredi Manizza
Scripps Institution of Oceanography
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Jens Terhaar
Climate and Environmental Physics - University of Bern
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Are Olsen
Geophysical Institute
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Ryohei Yamaguchi
Japan Agency for Marine-Earth Science and Technology
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Peter Landschützer
Flanders Marine Institute (VLIZ)
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Eiji Watanabe
Japan Agency for Marine-Earth Science and Technology
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Dustin Carroll
Moss Landing Marine Laboratories
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Hanani Adiwara
Tohoku University
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Jens Daniel Müller
ETH Zürich
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Judith Hauck
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research
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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 8 surface ocean pCO2-observation products, 18 ocean biogeochemical hindcast and data assimilation models and 6 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 and 92 ± 30 TgC yr−1 in the models. The CO2 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−1dec-1 in the pCO2 products and 10 ± 4 TgC yr−1dec-1 in the models. 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. Both, the mean CO2 uptake and the trend, is substantially weaker in the atmospheric inversions. Uncertainties across all estimates are large, in the pCO2 products because of scarcity of observations and in the models because of missing processes.
21 May 2023Submitted to ESS Open Archive
22 May 2023Published in ESS Open Archive