I'm with Alan on this one.
With 3 C warming offset by SAI, if done thoughtfully the society and
agriculture would have been adjusting along the way, and then comes
nuclear war to disturb that ongoing situation.
And as the SCOPE study on the consequences of nuclear war made clear,
there is the matter of the direct damage. As that report noted it would
take destruction of only a few of the world's financial centers to
collapse international trade of medicines, seeds, fertilizers, grain and
much more (computer chips, coffee). As we are seeing from the invasion
of Ukraine, which is one of the top exporters of grains and fertilizer,
disrupting this producing area has prospects for causing widespread
starvation. For each of the major grains in international trade,
something like 90% comes from typically five countries or so, with their
exports going to of order 100 countries importing the grain in order to
provide reasonably priced food for their people. And then add sudden
disruption of the weather in these key zones and making it difficult for
nations around the world, global nuclear war would be overwhelmingly worse.
What would happen to the conditions of the following years might be of
theoretical interest, but the consequences of the first months and year
would have created such disruption that the society you'd be considering
would be almost unimaginably different.
Mike MacCracken
On 7/26/22 11:20 AM, Gideon Futerman wrote:
Dear Dr Robock,
Whilst I would admit that 3K of cooling by SRM is unlikely, it is
certainly not out of the range of possibility. Given CO2
concentrations of 550PPM have a 10% chance of leaving us with 6K of
warming (and that certainly doesn't seem to be an unreasonable amount
of emissions given mitigation trajectories), it certainly doesn't seem
like there is a less than 10% probability of a given deployment scheme
being 3K of forcing.
Secondly, why care about this if there is a nuclear war. Maybe you are
correct, and there is no worry. But if you care about post-nuclear war
societal recovery, it may be important to know whether SRM-driven
termination shock makes that more or less likely, or is entirely
negligible. Of course, the primary worry here is avoid the initial
catastrophe (nuclear war). Nonetheless, the question of whether SRM
termination shock under nuclear war has any effect (even if only 10%
of the magnitude of the effects of the nuclear war) is significant.
I am trying to look at low probability, heavy tailed risks of SRM,
including how it interacts with other risks. This is why I want to
look at the (relatively unlikely) scenario which I have laid out.
And apologies for the spelling mistake, spelling is certainly not my
strong suit!
Kind Regards
Gideon Futerman
He/Him
www.resiliencer.org
On Tuesday, 26 July 2022 at 16:05:48 UTC+1 Alan Robock wrote:
Dear Gideon,
It is spelled "negligible." And nobody is suggesting enough SAI
to produce 3K cooling, because that means there has been no
mitigation.
A nuclear war could kill billions of people from starvation, and
would collapse civilization, surely reducing greenhouse gas
emissions. Why would you even worry about global warming and
geoengineering then? That's why I say your are comparing two
things that are of completely different scales.
Alan Robock
Alan Robock, Distinguished Professor
Department of Environmental Sciences Phone:
+1-848-932-5751 <tel:(848)%20932-5751>
Rutgers University E-mail:
[email protected]
14 College Farm Road http://people.envsci.rutgers.edu/robock
New Brunswick, NJ 08901-8551 ☮ https://twitter.com/AlanRobock
Signature
On 7/26/2022 10:59 AM, Gideon Futerman wrote:
Dear Alan Robock,
When you say overwhelm, is the suggestion here that the increase
in radiative forcing from the termination of aerosol injection
would be entirely negligable compared to the nuclear winter scenario?
If SAI were masking 3K of warming, and you got a nuclear winter
driven cooling of say 7K, surely the impact of the termination of
SAI would not be negligable, even if it would be significantly
less than the cooling of nuclear winter (ie you still get a
nuclear winter)? I am trying to work out if the "double
catastrophe" as Baum calls it actually applies in the nuclear
winter scenario. So the question of whether the removal of the
contribution of SAI to radiative forcing (by termination) makes
the nuclear winter (and the resulting warming afterwards) worse,
less bad or is entirely negligable is important.
Moreover might sunlight removal effects be important in the short
term, particularly if it were a relatively high SAI radiative
forcing and (relatively) minor nuclear winter (say about 6K of
cooling)? Given up to 50% of sulfate aerosols remain in the
stratosphere up to 8 months after termination, would the added
impact of the sulfate aerosols on top of the significantly more
soot aerosols have an effect of sunlight available for
photosynthesis, so increase impact on food production in the
early days of the nuclear winter? Or would this simply be
negligable in the face of the radiation reduction from even a
relatively minor nuclear winter?
Kind Regards
Gideon
On Tuesday, 26 July 2022 at 15:20:44 UTC+1 Alan Robock wrote:
Dear Gideon,
A nuclear war would be orders of magnitude worse than any
impacts of SAI or termination. Soot from fires ignited by
nuclear attacks on cities and industrial areas would last for
many years, and would overwhelm any impacts from shorter
lived sulfate aerosols. Of course the impacts depend on how
much soot, but a war between the US and Russia could produce
a nuclear winter. For more information on our work and the
consequences of nuclear war, please visit
http://climate.envsci.rutgers.edu/nuclear/
Alan Robock
Alan Robock, Distinguished Professor
Department of Environmental Sciences Phone:
+1-848-932-5751 <tel:(848)%20932-5751>
Rutgers University E-mail:
[email protected]
14 College Farm Road http://people.envsci.rutgers.edu/robock
New Brunswick, NJ 08901-8551 ☮ https://twitter.com/AlanRobock
Signature
On 7/26/2022 10:03 AM, Gideon Futerman wrote:
As part of the RESILIENCER Project, we are looking at low
probability high impact events and their relation to SRM.
One important worry in this regards becomes termination
shock, most importantly what Baum (2013) calls a "Double
Catastrophe" where a global societal collapse caused by one
catastrophe then causes termination shock, another
catastrophe, which may convert the civilisational collapse
into a risk of extinction.
One such initial catastrophe may be nuclear war. Thus, the
combination of SRM and nuclear war may be a significant
worry. As such, I am posing the question to the google
group: what would happen if SRM (either stratospheric or
tropospheric- or space based if you want to go there) was
terminated due to a nuclear war? What sort of effects would
you expect to see? Would the combination worsen the effects
of nuclear war or help ameliorate them? How would this
differ between SRM types?
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