Even a Small Nuclear Showdown Would Mean Worldwide Disaster

By Sarah Zhang on at

In these decades after the Cold War, "nuclear winter" is an idea that can feel as remote as science fiction. But using state-of-the-art climate models, scientists have calculated exactly what nuclear winter will look like after even a small, regional conflict. Boy is it bad.

This uplifting climate news come to us from a journal called Earth's Future, which published a study recently unearthed by Francie Diep at Popular Science. The hypothetical scenario is nuclear war between India and Pakistan. Two sides each drop fifty 15 kiloton bombs — peanuts compared to the nuclear arsenals of the US and Russia — before abating. What then?

Let's get started.

In the minutes after a nuclear explosion, everything in the vicinity is burning hot. Tiny particles of black carbon begin to rise up from the burning wreckage, eventually accumulating to five megatons in the atmosphere. Black carbon, which loves to absorb sunlight, has two related effects: 1.) the Earth gets colder and 2.) the stratosphere gets hotter. Both have massive consequences, not just for India and Pakistan, but for the entire planet.

If you just look at the numbers for cooling, the temperature changes seem unimpressive. After one year, the global average surface temperature drops about two degrees Fahrenheit and after five years, about 2.88 degrees. Pssh, right? But for that same reason a few degrees of global warming are Big Deal, tiny changes in global averages ripple out. The temperature change would cause global precipitation to fall on average by 9 per cent. Break away from averages, and things get more extreme. The monsoon region in Asia could see rainfall reduced by 20 to 80 per cent.

The changes in rainfall and temperature will especially hit us where it hurts: our stomachs. The growing season will be shortened by up to 40 days in some areas, so expect starvation to get worse.

And that's not even to mention the ozone: as black carbon prevents heat from reaching land, it absorbs all that heat into the stratosphere. This extra heat in the stratosphere begins to break down the layer of ozone that normally protects us from the sun's radiation. Ozone will be reduced by 20 to 25 per cent in years two to five after the nuclear war.

The extra UV radiation in nuclear winter (ironically not from the bombs themselves) will disrupt crop growth and kill phytoplankton, the basis of the marine food chain. And it'll be bad for us, too: the authors estimate that you'll get sunburned twice as fast, which means more skin cancer.

Perhaps what's most striking about the climate model is that while the Earth does slowly recover, the cooling effects are felt even two decades after the war. (Which, let us remind you again, is a relatively small, regional one.) War is devastating, but nuclear war's devastation extends even further and longer. [Earth's Future via Popular Science]

Top image: Nuclear weapon test on Bikini Atoll in 1954. DOE