If the goal is to restore ocean chemistry, it would indeed seem inherently inefficient to do so via CO2 removal from air. Better to remove excess CO2 from the ocean by chemical, geochemical, or biological means (1), my favorite being alkalinity addition. Secondly, according to the IPCC (2) and now UNEP (3), RCP 2.6 scenarios cannot be achieved without CDR - in the UNEP estimate, 300 Gts CO2 worth by 2100. So while I don't think anyone is asking CDR to do all of the heavy lifting, it would appear that at least some CDR is essential to achieve RCP 2.6 and probably even less ambitious scenarios, depending on when/if we ever get serious about emissions reduction. What then is the point of dissing CDR if emissions reduction alone isn't going to save the ocean and the planet either?
1) http://link.springer.com/referenceworkentry/10.1007/978-94-007-5784-4_54 2) http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter06_FINAL.pdf 3) http://www.unep.org/emissionsgapreport2014/ Greg -------------------------------------------- On Mon, 8/3/15, Andrew Lockley <[email protected]> wrote: Subject: [geo] Long-term response of oceans to CO2 removal from the atmosphere To: "geoengineering" <[email protected]> Date: Monday, August 3, 2015, 1:02 PM http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2729.html Long-term response of oceans to CO2 removal from the atmosphere Sabine Mathesius,1, 2, Matthias Hofmann,1, Ken Caldeira3, & Hans Joachim Schellnhuber1, 4, Nature Climate Change (2015): doi:10.1038/nclimate2729 Published online 03 August 2015 Abstract Carbon dioxide removal (CDR) from the atmosphere has been proposed as a measure for mitigating global warming and ocean acidification. To assess the extent to which CDR might eliminate the long-term consequences of anthropogenic CO2 emissions in the marine environment, we simulate the effect of two massive CDR interventions with CO2 extraction rates of 5 GtC yr−1 and 25 GtC yr−1, respectively, while CO2 emissions follow the extended RCP8.5 pathway. We falsify two hypotheses: the first being that CDR can restore pre-industrial conditions in the ocean by reducing the atmospheric CO2 concentration back to its pre-industrial level, and the second being that high CO2 emissions rates (RCP8.5) followed by CDR have long-term oceanic consequences that are similar to those of low emissions rates (RCP2.6). Focusing on pH, temperature and dissolved oxygen, we find that even after several centuries of CDR deployment, past CO2 emissions would leave a substantial legacy in the marine environment. -- 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 http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout. -- 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 http://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
