And in respect to cost, discharge large ships loaded with olivine grit in shallow seas with strong bottom currents. The mutual impact of these coarse grains in the current effectively knock off small slivers of olivine which react within ten days in the sea, and it saves you the cost of fine milling (and the associated energy/CO cost). Olaf Schuiling
From: [email protected] [mailto:[email protected]] On Behalf Of Ronal W. Larson Sent: dinsdag 11 augustus 2015 23:45 To: [email protected] Cc: Sabine Mathesius; Geoengineering Subject: Re: [geo] Long-term response of oceans to CO2 removal from the atmosphere Greg: cc Sabine and list Can you give your own cite or two to support this sentence from below? “I also think that your modeling could make a strong case that CDR that generates ocean alkalinity is the preferred CDR method.” I have been thinking that every molecule (or tonne or Gigaton of C) taken from the atmosphere has the same impact (all being quite quick) on ocean acidity/alkalinity. So I would think cost is the main criterion, assuming no major negative down sides. Ron On Aug 11, 2015, at 2:36 PM, Greg Rau <[email protected]<mailto:[email protected]>> wrote: I'm with you on the idea that there is no better way to manage GHG's and their impact than to reduct GHG emissions. Thanks for pointing this out. But if we continue to fail to adequately reduce emissions, wouldn't CDR be better than no action at all, as you modeling shows? And what is the better alternative to CDR for mitigating all of the CO2 that has already been and will be emitted (and associated climate and ocean effects) before we get to zero emissions? I also think that your modeling could make a strong case that CDR that generates ocean alkalinity is the preferred CDR method. How about modeling the ocean chem recovery rate when 5Gt or 25 Gt CO2/yr are consumed via via enhanced mineral weathering and the resulting alkalinity added to the ocean? Get in touch if you want to collaborate on this. Greg -------------------------------------------- On Sat, 8/8/15, Sabine Mathesius <[email protected]<mailto:[email protected]>> wrote: Subject: Re: [geo] Long-term response of oceans to CO2 removal from the atmosphere To: "Greg Rau" <[email protected]<mailto:[email protected]>>, "geoengineering" <[email protected]<mailto:[email protected]>> Cc: [email protected]<mailto:[email protected]> Date: Saturday, August 8, 2015, 9:10 AM Hi, just a short clarification: The main point of our study is not that CDR is useless, but that it is not effective enough to counteract business as usual CO2 emissions. Our results stress, once again, that there is no alternative to immediate emissions reduction - CDR can be deployed as a supplemental measure (and maybe it should), but it would not be effective enough to reverse severe changes caused by a delay in emissions reduction. On alkalinity addition: How likely is it that we would be able to do this on a global scale? I could imagine that alkalinity addition might be a way to protect a coral reef, being deployed locally, but globally? I guess it would be much harder to do than atmospheric CDR and you would have to be very careful how much alkalinity you add and how often, to not further stress marine organisms? As far as I know, there are hardly any studies on this? (By the way, our study is not only about ocean acidification, but also about warming and oxygen depletion.) Best, Sabine On 08/08/15 12:50 am, Greg Rau wrote: 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]<mailto:[email protected]>> wrote: Subject: [geo] Long-term response of oceans to CO2 removal from the atmosphere To: "geoengineering" <[email protected]<mailto:[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. 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