| The importance of ocean transport in the fate of anthropogenic CO<sub>2</sub> (2008) | |||||||||
Abstract | |||||||||
| We assess uncertainties in projected oceanic uptake of anthropogenic CO<sub>2</sub> associated with uncertainties in model ocean transport using a suite of climate/carbon-cycle models. In response to a CO<sub>2</sub> pulse emission of 590 Pg C (corresponding to an instantaneous doubling of atmospheric CO<sub>2</sub> from 278 to 556 ppm), the fraction of CO<sub>2</sub> emitted absorbed by the ocean (model mean ±2σ) is 37±8%, 56±10%, and 81±4% in year 30, 100, and 1000 after the emission pulse, respectively. Modeled oceanic uptake of excess CO<sub>2</sub> on timescales from decades to about a century is strongly correlated with simulated present-day uptake of chlorofluorocarbons (CFCs) and anthropogenic CO<sub>2</sub>, while the amount of excess CO<sub>2</sub> absorbed by the ocean from a century to a millennium is strongly correlated with modeled radiocarbon in the deep Southern and Pacific Ocean. The rates of surface-to-deep ocean transport are determined for individual models from the instantaneous doubling CO<sub>2</sub> experiments, and they are used to calculate oceanic uptake of CO<sub>2</sub> in response to emission pulses of 1000 and 5000 Pg C. These results are compared with simulated oceanic uptake of CO<sub>2</sub> from a number of model simulations with the coupling of climate-ocean carbon cycle and without it. This comparison demonstrates that the impact of different ocean transport rate across models on the oceanic uptake of anthropogenic CO<sub>2</sub> is of similar magnitude as that of climate-carbon cycle feedbacks in a single model associated with changes in temperature, circulation, and marine biology, emphasizing the importance of ocean transport in the fate of anthropogenic CO<sub>2</sub>. | |||||||||
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