Hi Ulrik, good to hear from you again!
We do not know what will happen if a nuclear weapon is again detonated offensively, other than that the world would be forever changed. This is a fear shared by pretty much everyone who deals with nuclear weaponry (including recent speeches at EAG London—such as John Gower, who we met before), and even without immediate retaliation the expected probability of a large scale future exchange would rise hugely in such a world. That’s what I meant about the “all bets are off” line.
Certainly, many countries would seek to acquire weapons under this scenario (especially if the use was against a non nuclear power, which breaks a further taboo), and even if there are no further detonations in 30 days, the chances of a full scale exchange in such a world may rise by an order of magnitude.
I’m not sure that second projection is correct, and I put the mean projected additional detonations at higher levels. However, even if it is an accurate projection, I think the core point of the article holds: An offensive detonation significantly raises the probability of large exchanges, and there is a baseline risk of such an exchange today anyway → Large exchanges with thermonuclear weaponry risk nuclear winters → this is worth considering in our calculus around the expected impacts of nuclear warfare.
Hi Ulrik,
I would agree with you there in large part, but I don’t think that should necessarily reduce our estimate of the impact away from what I estimated above.
For example, the Los Alamos team did far more detailed fire modelling vs Rutgers, but the end result is a model that seems to be unable to replicate real fire conditions in situations like Hiroshima, Dresden and Hamberg → more detailed modeling isn’t in itself a guarantee of accuracy.
However, the models we have are basing their estimates at least in part on empirical observations, which potentially give us enough cause for concern:
-Soot can be lofted in firestorm plumes, for example at Hiroshima.
-Materials like SO2 in the atmosphere from volcanoes can be observed to disrupt the climate, and there is no reason to expect that this is different for soot.
-Materials in the atmosphere can persist for years, though the impact takes time to arrive due to inertia and will diminish over time.
The complexities of modeling you highlight raise the uncertainties with everything above, but they do not disprove nuclear winter. The complexities also seem raise more uncertainty for Los Alamos and the more skeptic side, who rely heavily on modeling, than Rutgers, who use modeling only where they cannot use an empirical heuristic like the conditions of past firestorms.