http://www.earth-syst-dynam-discuss.net/esd-2016-20/
Revisiting ocean carbon sequestration by direct injection: A global carbon budget perspective Fabian Reith, David P. Keller, and Andreas Oschlies Geomar : 28 Apr 2016 Abstract. In this study we look beyond the previously studied effects of oceanic CO2 injections on atmospheric and oceanic reservoirs, and also account for carbon cycle and climate feedbacks between the atmosphere and the terrestrial biosphere. Considering these additional feedbacks is important since backfluxes from the terrestrial biosphere to the atmosphere in response to reducing atmospheric CO2 can further offset the targeted reduction. To quantify these dynamics we use an Earth-system model of intermediate complexity to simulate direct injection of CO2 into the deep ocean as a means of emissions mitigation during a high CO2 emission scenario. In three sets of experiments with different injection depths, we simulate a 100-year injection period of a total of 70 GtC and follow global carbon cycle dynamics over another 900 years. Simulated seawater chemistry changes and marine carbon storage effectiveness are similar to previous studies. As expected, by the end of the injection period avoided emissions fall short of the targeted 70 GtC by 16 % to 30 % as a result of carbon cycle feedbacks and backfluxes in both land and ocean reservoirs. An unexpected feature are effects of the model's internal variability of deep-water formation in the Southern Ocean, which, in some model runs, causes additional oceanic carbon uptake after injection termination relative to a control run without injection and therefore with slightly different atmospheric CO2 and climate. These results of a model that has very low internal climate variability illustrate that attribution of carbon fluxes and accounting for injected CO2 may be very challenging in the real climate system with its much larger internal variability. Citation: Reith, F., Keller, D. P., and Oschlies, A.: Revisiting ocean carbon sequestration by direct injection: A global carbon budget perspective, Earth Syst. Dynam. Discuss., doi:10.5194/esd-2016-20, in review, 2016. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
