Hi Doug, Regarding your comment about risks, I think you make a fair point - it may be that we overstated the risks of 1C cooling by 2050, in which case our scenario might be even more policy-relevant.
Thanks for the feedback! Josh On Thu, May 1, 2025 at 6:15 PM Smith, Wake <[email protected]> wrote: > Doug — Addressing the first item below, there was an earlier draft of the > paper that dwelt on just the distinction you note regarding engine vs > airframe capabilities. I agree that engines are harder and and the > capabilities are rarer, but as matters shook out, we ended up cutting this > text and blurring the distinction. > > Wake Smith > Lecturer: Yale School of the Environment & > Research Fellow: Mossavar-Rahmani Center for Business & Government; > Harvard Kennedy School > [email protected] > 1 914 649 7722 > ------------------------------ > *From:* Douglas MacMartin <[email protected]> > *Sent:* Wednesday, April 30, 2025 9:57 AM > *To:* [email protected] <[email protected]>; > geoengineering <[email protected]> > *Cc:* Smith, Wake <[email protected]> > *Subject:* RE: [geo] New Paper on US, China, and Big Geoengineering > > > Hi Josh, > > > > This is great; so glad to see this out finally! > > > > One question, one comment: > > - Curious why you included countries on the list of having the > technical capability that don’t make aircraft engines; of the two (engines > or airframe) would seem to me that the engines are both harder to develop > capacity from scratch, and harder to acquire from another country if that > country doesn’t want you to buy them. I wouldn’t have included Canada or > India or Brazil on the list for this reason. > > - The scenario you describe is entirely reasonable choice for > this paper, but I’m curious about the phrase “it would involve a cooling > rate of approximately 0.5°C per decade, more than twice as fast as current > warming rates and enough to create obvious risks”. Current rate of > warming is close to +0.25C per decade, so increasing the amount of cooling > by 0.5C per decade simply leaves the overall rate of change the same as it > is now but with the opposite sign. (So that a decade into deployment, the > global mean temperature would be roughly what it had been a decade before > deployment started.) Given that most ecosystems (or human systems) won’t > yet have adapted to temperatures at the start of deployment, I’d think it > actually quite safe to assume that provided that an incremental use of SAI > does indeed reduce risks in general, while it’s clear that there is some > threshold that is too much, or too fast, that using enough to bring > temperatures back towards something ecosystems (and people) are better > adapted to would still reduce risks and be quite clearly below that unknown > threshold. Yet you write that this would create “obvious risks”… given > that it isn’t obvious to me, it obviously isn’t obvious, so I’m curious > what risks you were referring to. > > > > doug > > > > *From:* [email protected] <[email protected]> *On > Behalf Of *Josh Horton > *Sent:* Friday, April 25, 2025 8:16 AM > *To:* geoengineering <[email protected]> > *Subject:* [geo] New Paper on US, China, and Big Geoengineering > > > > Hi all, > > > > Check out my new paper with Wake Smith and David Keith on the US, China, > and Big SRM: > > > > “Who Could Deploy Stratospheric Aerosol Injection? The United States, > China, and Large- Scale, Rapid Planetary Cooling” > > *Stratospheric aerosol injection, which would reflect a small fraction of > sunlight away from the Earth to lower temperatures, involves many > unanswered questions. One of these is, who could deploy it? We consider > this with reference to a scenario in which global temperatures are reduced > by 1°C by midcentury; we term this a ‘PLUS’ deployment—Planetary, Large- > scale, Uninterrupted, and Speedy. The technical requirements of a PLUS > deployment—a fleet of a hundred or more specialized air- craft—limit the > number of capable actors to ten states. The geopolitical requirements > broad- spectrum capabilities sufficient to overcome external > constraints—mean that only the US and China are capable of implementing > unilaterally against strong opposition. As such, the US and China will be > decisive in determining whether and how a PLUS- type deployment takes > place. In particular, the degree of Sino- American alignment on this issue > will strongly influence the likelihood of a PLUS deployment and its > disruptive potential. We examine three cases in which activities with the > potential to harm global commons were debated during the Cold War: > scientific research in Antarctica, atmospheric testing of nuclear weapons, > and experiments in outer space. Backed by evidence from these cases, we > then consider several implications of our findings.* > > Josh Horton > > -- > 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 view this discussion visit > https://groups.google.com/d/msgid/geoengineering/8023bf9a-d68e-4030-9ab4-a83e567ca8e6n%40googlegroups.com > <https://groups.google.com/d/msgid/geoengineering/8023bf9a-d68e-4030-9ab4-a83e567ca8e6n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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