[ExI] mutual assured injury

[Anders]

On 2016-11-06 01:50, spike wrote:
>
> My intuition is that somehow the overall impact would need to be 
> cooling in the short run, net warming in the long run. Reasoning: soot 
> in the upper atmosphere (the remains of USA and Russia) would decrease 
> albedo so in the long run would absorb more solar energy while 
> blocking solar energy to the surface in the short run.
>
The issue is that the stratosphere is efficient at re-radiating higher 
temperatures to space, while the troposphere isn't. Make the 
stratosphere black and it heats up (which contributes to the stability 
of the nuclear winter), but most of the absorbed heat is emitted into 
space rather than down to the ground.

> I am looking into the bovine models.  We are told that cow farts are 
> introducing huge amounts of methane into the atmosphere, and that 
> corn-fed cows create way more methane than grass-fed.  My intuition 
> drives me to conclude that we could create enormous vats in which we 
> mimic whatever reaction is taking place inside cows, convert corn to 
> methane directly, use that to greenhouse our way over the cold decade 
> after we nuke ourselves.
>

Unfortunately, methane has GWP of merely 86 times CO2. So you would need 
to boost the methane content like 1/86 of the CO2 that would counteract 
the nuclear winter. We are talking about 10+ degrees here, so we would 
need something like an increase of methane emissions by a factor of 12+. 
So we are talking about 360 million tons per year or more.

I think ameliorating nuclear (or asteroid, or supervolcano) winter using 
greenhouse gas is not totally crazy. Many fluorocarbons have much 
greater greenhouse potential (carbon tetraflouride has 50,000!) You 
would need to manufacture and release them in the aftermath of a nuclear 
war which is tough, and I can see some serious issues about both risks 
of having stores (if there was an accidental or deliberate release they 
would do bad things to a normal climate). There are also the problem 
with lack of light and ozone layer, which would be bad for agriculture 
even if it was not freezing. But these issues can be analysed and worked 
out, and I think they should be checked just in case.


-- 
Dr Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

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