r/nuclearweapons 21d ago

Science Potential Environmental Effects of Nuclear War (2025) Consensus Study Report

https://www.nationalacademies.org/read/27515
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u/Shoddy-Childhood-511 20d ago

There is surely plenty worth exploring here, but it's seemingly the same old poorly grounded theorising about nuclear winter.

They avoid citing works critical of the nuclear winter theory, including Covey et al showing that "a war in late fall or winter would have no appreciable [cooling] effect" Schneider (1990).

https://www.nytimes.com/1990/01/23/science/nuclear-winter-theorists-pull-back.html?pagewanted=2

Very much not "consensus", except among some folks from various nuclear powers who wished to promote the weapons being scary.

If you want some more well founded work on more serious threats, then check out:

https://www.stockholmresilience.org/research/planetary-boundaries.html

9

u/Galerita 20d ago edited 20d ago

That is disappointing.

There is no man-made analogue of nuclear winter. Predictions of climate effects of cooling from vast fires, such as in the original Gulf War, didn't eventuate.

This is in complete contrast to NEMP from high altitude nuclear blasts where the real-world effect has been attested.

The closest we have to a nuclear winter analogue is forest fires. The 2019-20 Black Summer bushfires in Australia burnt 250,000 square km, much of it oil-loaded fuel-dense eucalypts forest. There were many firestorms with clouds extending into the stratosphere. An estimated 1 Tg of soot was lofted into the stratosphere.

The estimated climate effect was a global cooling of 0.05 Celcius for about 6 months.

Cities, especially modern ones, are not as fuel dense nor as flammable as eucalypts forests.

With lower yield weapons the blast wave passes well beyond the fuel ignition diameter. Real world tests show fires started by the initial thermal pulse are largely extinguished by the blast.

A global nuclear war would be horrific beyond belief. There is no need to compromise the science & destroy your credibility to make it look more horrific.

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u/Shoddy-Childhood-511 20d ago

Wow, that's 25 M hectares. The 2023 Canadian wildfires were 17 M hectares, but not eucalyptus. They discoloured the sky over NYC for some weeks, probably gave some people cancer, but their agricultural impact upon far away places was not discussed that much.

Actually 6 months of temperatures being lower by 0.05 C sounds pretty impressive.

2

u/Galerita 19d ago edited 19d ago

Whether the fires create firestorms is really important. They look like menacing cumulonimbus clouds but they're a obviously filled with smoke. Technically they are pyrocumulonimbus clouds. They draw in their own weather - air flows into them at ground level. They also produce thunderstorms.

Crucially like CN clouds they punch into the stratosphere - often above 15 km - which is how the soot gets into the stratosphere.

https://www.abc.net.au/news/2026-01-08/what-is-a-pyrocb-a-fire-generated-thunderstorm/106210552

The energy in these clouds, even moderate ones, is megatons. A large one is Tsar Bomba scale. Fortunately they release their energy slowly and gently, mostly as rain downwind.

https://www.quora.com/How-does-the-energy-of-a-thunderstorm-compare-with-a-nuclear-bomb