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Reconciling Observation and Model Trends in North Atlantic Surface CO 2
Author(s) -
Lebehot Alice D.,
Halloran Paul R.,
Watson Andrew J.,
McNeall Doug,
Ford David A.,
Landschützer Peter,
Lauvset Siv K.,
Schuster Ute
Publication year - 2019
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2019gb006186
Subject(s) - biogeochemistry , environmental science , north atlantic deep water , climatology , sink (geography) , surface water , climate model , oceanography , atlantic multidecadal oscillation , structural basin , thermohaline circulation , geology , climate change , geography , paleontology , cartography , environmental engineering
The North Atlantic Ocean is a region of intense uptake of atmospheric CO 2 . To assess how this CO 2 sink has evolved over recent decades, various approaches have been used to estimate basin‐wide uptake from the irregularly sampled in situ CO 2 observations. Until now, the lack of robust uncertainties associated with observation‐based gap‐filling methods required to produce these estimates has limited the capacity to validate climate model simulated surface ocean CO 2 concentrations. After robustly quantifying basin‐wide and annually varying interpolation uncertainties using both observational and model data, we show that the North Atlantic surface ocean fugacity of CO 2 ( f CO 2−ocean ) increased at a significantly slower rate than that simulated by the latest generation of Earth System Models during the period 1992–2014. We further show, with initialized model simulations, that the inability of these models to capture the observed trend in surface f CO 2−ocean is primarily due to biases in the models' ocean biogeochemistry. Our results imply that current projections may underestimate the contribution of the North Atlantic to mitigating increasing future atmospheric CO 2 concentrations.