Can We Talk About the Climate Impacts of Nuclear War?

March 10, 2022

I remember talking to people about the effects of nuclear war back in the 80s. Supposedly educated people had really, no effing idea of what a nuclear detonation means.
I think that’s still true today.

Rob Meyer in Atlantic:

If you are worried about rapid, catastrophic changes to the planet’s climate, then you must be worried about nuclear war. That is because, on top of killing tens of millions of people, even a relatively “minor” exchange of nuclear weapons would wreck the planet’s climate in enormous and long-lasting ways.

Consider a one-megaton nuke, reportedly the size of a warhead on a modern Russian intercontinental ballistic missile. (Warheads on U.S. ICBMs can be even larger.) A detonation of a bomb that size would, within about a four-mile radius, produce winds equal to those in a Category 5 hurricane, immediately flattening buildings, knocking down power lines, and triggering gas leaks. Anyone within seven miles of the detonation would suffer third-degree burns, the kind that sear and blister flesh. These conditions—and note that I have left out the organ-destroying effects of radiation—would rapidly turn an eight-mile blast radius into a zone of total human misery. But only at this moment of the war do the climate consequences truly begin.

The hot, dry, hurricane-force winds would act like a supercharged version of California’s Santa Ana winds, which have triggered some of the state’s worst wildfires. Even in a small war, that would happen at dozens of places around the planet, igniting urban and wildland forest fires as large as small states. A 2007 study estimated that if 100 small nuclear weapons were detonated, a number equal to only 0.03 percent of the planet’s total arsenal, the number of “direct fatalities due to fire and smoke would be comparable to those worldwide in World War II.” Towering clouds would carry more than five megatons of soot and ash from these fires high into the atmosphere.

All this carbon would transform the climate, shielding it from the sun’s heat. Within months, the planet’s average temperature would fall by more than 2 degrees Fahrenheit; some amount of this cooling would persist for more than a decade. But far from reversing climate change, this cooling would be destabilizing. It would reduce global precipitation by about 10 percent, inducing global drought conditions. In parts of North America and Europe, the growing season would shorten by 10 to 20 days.

This would prompt a global food crisis the world hasn’t seen in modern times. Corn, wheat, and soybean yields would all decline by more than 11 percent over five years. In a slightly larger conflict—involving, say, 250 of the world’s 13,080 nuclear weapons—the oceans would become less bountiful; the photosynthesizing plankton that form the basis of the marine food chain would become 5 to 15 percent less productive. In the case of a U.S.-Russia war, fishers worldwide would see their catches decline by nearly 30 percent.

And even though the world would get cooler, the nuclear winter resulting from a full-blown global conflict (or even “nuclear fall,” as some researchers prefer) would not reverse the effect of what we might morbidly call “traditional” human-caused climate change. In the short term, the effects of ocean acidification would get worse, not better. The layer of smoke in the atmosphere would destroy as much as 75 percent of the ozone layer. That means that more UV radiation would slip through the planet’s atmosphere, causing a pandemic of skin cancer and other medical issues. It would affect not just humans, either—even on the remotest islands, the higher UV rates would imperil plants and animals otherwise untouched by the global carnage.

Nowadays, we don’t tend to think of nuclear war as a climate problem, but concerns over these kinds of dangers were part of how modern climate change achieved political prominence in the first place. During the 1980s, a set of scientists raised the alarm about the effects of a nuclear winter and of the growing “hole in the ozone layer.” As the Stanford professor Paul N. Edwards writes in A Vast Machine, his magisterial history of climate modeling, these environmental issues taught the world that the planet’s entire atmosphere could come under threat at once, priming the public to understand the risks of global warming.

And even before that, climate science and nuclear-weapons engineering were twin disciplines of a sort. John von Neumann, a Princeton physicist and member of the Manhattan Project, took interest in the first programmable computer in 1945 because he hoped that it could solve two problems: the mechanics of a hydrogen-bomb explosion and the mathematical modeling of Earth’s climate. At the time, military interest in meteorology was high. Not only had a good weather forecast helped secure Allied victory on D-Day, but officials feared that weather manipulation would become a weapon in the unfolding Cold War.

The worst fears of that era, thankfully, never came to pass. Or at least, they haven’t happened yet. It is up to us to make sure that they don’t.

Outside of the direct effects of the bombs themselves, the full effect of a nuclear exchange could be even worse. If several years of gasoline- and diesel-fueled conventional military operations followed the global destruction, then the permanent consequences for the climate system would be even worse. That would also be true if society tried to rebuild by undertaking a fossil-powered reconstruction—and that would very likely be the case. The ruins of our postwar society would be poorer, and fossil reserves are the easiest energy sources to locate. Renewables, wind turbines, and other decarbonization technology, meanwhile, require secure factories, highly educated engineers, and complicated global networks of trade and exchange. They depend, in other words, on everything that peace provides. Solving climate change is a luxury of a planet at peace with itself.

Below, Nuclear detonation scene from Terminator 2.
This from the comment thread, unverified:

“James Cameron said he got a letter from the Lawrence Livermore Labs, where they develop nuclear weapons, telling him that this scene has the single most accurate depiction of a nuclear weapon in movies. That freaked him out, understandably; this is horrifying.”

2 Responses to “Can We Talk About the Climate Impacts of Nuclear War?”

  1. Jim Torson Says:

    NUKEMAP allows you to see the effects of a nuclear blast near your location.
    Just remember to “duck and cover.”

    • rhymeswithgoalie Says:

      During the Cold War, my response to a spiking nuclear threat would be to head to the most likely ground zero in the vicinity. I wasn’t a big fan of surviving a nuclear war.

      I bet the “prepper” community (and the people who market to them) are having a high old time.

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