My ill structured ramblings on unknowns below
* Aerosol coalescence in steady state, and resulting sedimentation * sedimentation effect on clouds, especially cirrus *steady state ozone loss *sedimentation environmental impacts of novel, engineered and/or insoluble particles * MCB plume behaviour (sink or rise, quite likely sink) * ocean CO2 dissolution from cooling (should be well constrained, but only one study) * more analysis of game theory / Socio-political factors regarding deployment (power blocs, clandestine deployment, rogue state, greenfinger - vs global consensus) *interactions between geoengineering in "cocktail" deployment (only one study) *costs of monitoring and governance *redo design & cost studies based on realistic future designs (unmanned, electric, H2 fuelled) *brainstorming on unknown unknowns, eg insect migration effects, plankton circadian rhythms, etc. *geoengineering observable or not by civilisations on other planets (and consequences/wisdom thereof) On 19 Jul 2017 21:58, "Douglas MacMartin" <macma...@cds.caltech.edu> wrote: > Hi Ken, > > > > We tried to write some down in our Earth’s Future piece last year, at > least for stratospheric aerosols > > MacMartin, D. G., B. Kravitz, J.C.S. Long, and P.J. Rasch, “Geoengineering > with stratospheric aerosols: what do we not know after a decade of > research?” *Earth’s Future*, *4*, 543-548, 2016. doi: 10.1002/2016EF000418 > <http://onlinelibrary.wiley.com/doi/10.1002/2016EF000418/epdf> > > > > I agree with some of what has been said, that some of the biggest/hardest > questions are on the societal side rather than climate science side, but I > don’t think very many people would agree to deployment based on what we > currently know on the climate science (I sure wouldn’t). > > > > I’d say what we know is simply that it is plausible that a limited > deployment of solar geoengineering in addition to (as opposed to an > alternative to) could reduce climate damages for most, and research has yet > to identify any “showstoppers”. We know that using solar geoengineering to > move global mean temperature all the way back to preindustrial will > overcompensate some variables and is almost certainly not a reasonable > balance of risk, but something like 3C à 1.5C **might** be less risk > (with appropriate caveating of aggregation, i.e., risk for whom) than > allowing the climate to warm to 3C. We know we can achieve at least a few > W/m2 of negative RF. > > > > There’s a lot of things we don’t know for stratospheric aerosols (and even > more for MCB or cirrus thinning), including stratospheric processes > (microphysics, chemistry, dynamics) and how the climate responds > differently to that RF in contrast to GHG forcing. It would be valuable as > a community to start trying to better quantify which uncertainties are most > important to resolve, how significant they might be on our ability as a > society to make informed decisions, and what modeling/observation/perturbative > field tests might help resolve them (including how resolvable some > uncertainty might be. Just to pick one random one, is the range of > possible unknown impact of sedimenting aerosols on cirrus significant > enough that it would affect our conclusions about impacts of a deployment? > If so, what would we need to do to understand that, how long would that > take, how much would that cost… Personally I’d like to talk to everyone at > the GRC next week to get their expert opinions on these types of questions > (as well as everyone who isn’t at the GRC). > > > > One thing I would like to push back on is the extent of “unknown > unknowns”… of course one can’t (by definition) bound that, but given the > natural analogs, is the possibility of these really significant in > comparison with the known knowns and known unknowns of never considering > geoengineering? > > > > See you in a few days, > > > > doug > > > > *From:* geoengineering@googlegroups.com [mailto:geoengineering@ > googlegroups.com] *On Behalf Of *Eric Durbrow > *Sent:* Thursday, July 20, 2017 2:20 AM > *To:* geoengineering <geoengineering@googlegroups.com> > *Subject:* Re: [geo] Help: What do we know and what don't we know about > solar geoengineering? > > > > Possible bullet points > > • It is virtually impossible to use SRM as an effective weapon. > > • However, some countries may see it as a weapon esp if deployed > unilaterally. > > > > > > On 19 July 2017 at 9:41:57 , Klaus Lackner (klaus.lack...@asu.edu) wrote: > > What are the most important things we know about solar geo-engineering? > > > > - It can be done, it is comparatively cheap, but probably not as cheap > as people think > - It will cool the planet, but it will not simply cancel out > greenhouse gas additions > - There is more than one way of doing it, some are more reversible > than others > - It is no substitute for balancing the carbon budget > - It acts fast, but needs constant maintenance > > > > What are the most important things we don’t know about solar > geo-engineering > > - Who decides > - Who pays for the unintended side effects > - What are the unintended side effects for different methods under > consideration > - Benefit – risk analysis over time > > > > > > *From: *<kcalde...@gmail.com> on behalf of Ken Caldeira < > kcalde...@carnegiescience.edu> > *Reply-To: *"kcalde...@gmail.com" <kcalde...@gmail.com> > *Date: *Wednesday, July 19, 2017 at 07:48 > *To: *Geoengineering <Geoengineering@googlegroups.com> > *Subject: *[geo] Help: What do we know and what don't we know about solar > geoengineering? > > > > Folks, > > > > This Sunday evening, I am supposed to help kick off a discussion about > what we know and what we don't know about solar geoengineering. > > > > https://www.grc.org/programs.aspx?id=17348 > <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.grc.org_programs.aspx-3Fid-3D17348&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=fgPmqux2N1LODT1cufk_CJiAKTZhRHIqK_n9LouQzTo&s=kUPAtZyNn31QnhDsOVyKJMJGsHpEG9CEKV8lyxPkMS8&e=> > > > > It would be helpful if some people on this group could attempt to answer > these questions: > > > > *1. What are the most important things we know about solar geoengineering?* > > > > *2. What are the most important things we don't know about solar > geoengineering?* > > > > I would appreciate it if you could put your answers in the form of bullet > points and not write essays. It would also help if you could cite a key > relevant paper or two. > > > > Thanks, > > Ken > > > > > *Ken Caldeira* > > *Carnegie Institution for Science* > > Dept of Global Ecology > > 260 Panama St > > Stanford CA 94305 USA > > +1 650 704 7212 <(650)%20704-7212> > > http://CarnegieEnergyInnovation.org > <https://urldefense.proofpoint.com/v2/url?u=http-3A__CarnegieEnergyInnovation.org&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=fgPmqux2N1LODT1cufk_CJiAKTZhRHIqK_n9LouQzTo&s=xTFR7pKw61rTex4OWOy9-gvMgRffknI8JWsUfksXA9U&e=> > > http://dge.stanford.edu/labs/caldeiralab > <https://urldefense.proofpoint.com/v2/url?u=http-3A__dge.stanford.edu_labs_caldeiralab&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=fgPmqux2N1LODT1cufk_CJiAKTZhRHIqK_n9LouQzTo&s=1ImkopEb-MSF21XBDO0gH_GUlkaeWWtZ_0jEOLfQGKI&e=> > > > > Assistant, with access to incoming emails: Jess Barker > jbar...@carnegiescience.edu > > -- > 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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at https://groups.google.com/group/geoengineering > <https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_group_geoengineering&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=fgPmqux2N1LODT1cufk_CJiAKTZhRHIqK_n9LouQzTo&s=YHrRHBE35Fj38UtdVrvJt4HXtvMxoYECg6gtWKh3Zpw&e=> > . > For more options, visit https://groups.google.com/d/optout > <https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_optout&d=DwMFaQ&c=l45AxH-kUV29SRQusp9vYR0n1GycN4_2jInuKy6zbqQ&r=hFjA8A8KwwhQx5qilpfIleTL0XYVr_fckT8DnwIEWlQ&m=fgPmqux2N1LODT1cufk_CJiAKTZhRHIqK_n9LouQzTo&s=WNRkwfY3WUM8IPeoLHfw3pymZI22ytE87wX3xGvz2so&e=> > . > > -- > 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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at https://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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at https://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 geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at https://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. 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