*(one proposal for possibly "squaring the circle on this" here: https://drive.google.com/file/d/1o5xQogx1kKgD-QlM4MVPdWeL2BzBtwUm/view?usp=sharing )*
On Thu, Mar 21, 2024 at 11:09 AM Ron Baiman <rpbai...@gmail.com> wrote: > > Dear Colleagues, > > An outstanding and extremely informative interview with Doug MacMartin > IMO on SAI (with some comments on MCB) shared recently by Andrew (thank > you!): > > https://www.youtube.com/live/_JBLMsXNmhs?si=3qoDl1RNLS4zb_zc > > who has also asked and posted in the geoengineering google group a number > of important follow up questions (that I've taken the liberty of copying > below this post.) > > A few observations that in some ways repeat what many of us have been > saying repeatedly: > > 1) As Doug (and many others - see for example transcription of Ted Parsons > - advisor to the Climate Overshoot Commission comment shared by Robert T) > and many others have pointed out, the key problem with SAI (as far as we > can tell at this point) appears to be political, or social science rather > than natural science based. After all, volcanoes have been doing this > throughout geological time with mostly (at least in human time frames) > non-catastrophic impact. > > 2) Of course ideally we would have perfect democratic participatory global > governance in place before we begin to pilot-test high leverage Direct > Climate Cooling (DCC) ( > https://drive.google.com/file/d/1jt-8OF7ncW71bEPqCDfJS5trr4-Nm4FJ/view?usp=sharing) > deployment, but if we wait for perfect global governance before deploying > we're allowing and risking (possibly very harmful) climate catastrophe > (that we might possibly be able to reduce or prevent) to continue (one > proposal for possibly "squaring the circle on this" here: > > 3) I thought the roughly 20 to 1 tradeoff (highlighted by Dan) between the > harmful to humans and nature cooling sulfate aerosols we've been > inadvertently emitting in the troposphere for decades, and roughly 5% of > these we would need to put up in the stratosphere (where they would also > have much less harmful impact on life on earth) to cool is a particularly > good communications "hook". We've been in effect conducting very harmful > and inefficient "geoengineering" for decades that we're now puting into > "reverse termination shock" (see: > https://drive.google.com/file/d/1R9Kg3d1DozwuxPIjyLWljb9Lld_pJCVm/view - > that is reportedly/hopefully now on the IMO MEPC meeting agenda). See also > HPAC discussions with Doug ( > https://drive.google.com/file/d/1EyMvarUBlzon4GNyZlOYrSzSQYpD_m_a/view) > and David Keith (https://muse.ai/vt/6mt51H5-Dr-David-Keith). > > 4) One quibble with Doug. Last I checked Make Sunsets was able to measure > how high up their balloons lofted, were using helium not hydrogen filled > balloons and to the best of my knowledge had roughly accurate (for > mid-latitude SAI) sulfate aerosol cooling impact estimates ( > https://makesunsets.com/blogs/news/calculating-cooling ). The problem > with Make Sunsets is that it is not "scalable" politically or > technologically (and I think MS agrees with this), but the effort has I > think (following PT Barnum "any publicity is good publicity") had > important political protest/awareness generating impact - see HPAC Make > Sunsets interview (https://muse.ai/v/AW112ix-Make-Sunsets). (As a > (radical) economist I appear to often be pointing out to many of my more > natural science and technology oriented colleagues the importance of > looking at political-economic, not just natural science, constraints and > affects.). > > Best, > Ron > > PS - Make Sunsets' (MS) hydrogen balloon proposal raises important > questions (MS refers to Make Sunsets) as noted by Andrew: > > "1) MS release lifting gas alongside S-compounds > 2) MS plan to use H2 > 3) H2 is an indirect GHG, GWP100 is ~11 > > https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1067144/atmospheric-implications-of-increased-hydrogen-use.pdf > https://www.nature.com/articles/s43247-023-00857-8 > 4) stratospheric H2 decomposes to H2O, a GHG > > I'm unclear on the following > A) does the indirect GWP100 of H2 increase if it's directly released into > the stratosphere? Common sense suggests so, but I can't see figures > anywhere > B) if stratospheric wetting is a problem, why isn't jet exhaust a problem? > It's very wet - C8H18 + 12 1/2O2 => 8CO2 + 9H2O. So in thin air ~1/3 of the > engine oxygen intake ends up as water. This applies to both commercial and > geoengineering flights. > C) is the above effect enough to net off the SAI? It doesn't seem so, SO2 > is a very strong negative forcing agent in the stratosphere." > > I'd welcome comments > > Andrew Lockley" > -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/geoengineering/CAPhUB9BwUcWQaN-YfdFMW5N7wxHT_HnYWaqCYCR4TMLOEdQDzg%40mail.gmail.com.
