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]> 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]> wrote:
>
> Subject: Re: [geo] Long-term response of oceans to CO2 removal from the
> atmosphere
> To: "Greg Rau" <[email protected]>, "geoengineering"
> <[email protected]>
> Cc: [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]>
> 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.
>>
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