There's at least one, admittedly reprehensible, way to reverse global warming fast: Nuclear war. NASA researchers say even a limited nuclear conflict could trigger an "unprecedented" planet-wide cooling that could last several years. But the devastating effects of the plunge in temperatures, not to mention the other consequences of nuclear bombs, would hurt the world for generations. Here, a quick guide:
How much colder would the world get?
A regional nuclear war would immediately cause average global temperatures to drop by 2.25 degrees Fahrenheit for the next two to three years. The most extremely affected areas — the tropics, Europe, Asia, and Alaska — would cool by up to 7.2 degrees, according to computer models. Even a decade after detonation, average world temperatures would remain nearly a full degree lower.
Why would temperatures plunge so far?
The explosions would send dust, soot, and ash into the sky, blotting out the sun for weeks. Smoke from the resulting fires would carry five million metric tons of black carbon into the Earth's atmosphere, where it would absorb the sun's heat.
How big of a nuclear war would it take to cool the planet?
Not that extensive, relatively speaking. These researchers used computer models assuming a war involving 50 to 100 bombs as big as the one the U.S. dropped on Hiroshima in World War II. That translates into just 0.03 percent of the world's current nuclear firepower. TIME ominously pointed out that India and Pakistan already have enough bombs in their arsenals to do the trick.
Would cooler weather really be so bad?
Yes. The soot would create holes in the ozone layer that would let more of the sun's ultraviolet rays hit Earth. Global precipitation levels would fall by 10 percent. That plus colder air would cause widespread crop failures. Consider the famine that struck Indonesia in 1815, when a volcano erupted, sending up an ash cloud that caused what was known as "the year without summer." Oh, and don't forget the nuclear radiation.