Nuclear war is a bad thing.
Scientists from NASA and a number of other institutions have recently been modeling the effects of a war involving a hundred Hiroshima-level bombs, or 0.03 percent of the world's current nuclear arsenal, according to National Geographic. The research suggests five million metric tons of black carbon would be swept up into the lowest portion of the atmosphere.
The result, according to NASA climate models, could actually be global cooling.
From National Geographic:
In NASA climate models, this carbon then absorbed solar heat and, like a hot-air balloon, quickly lofted even higher, where the soot would take much longer to clear from the sky.
While the global cooling caused by superpower-on-superpower war could be catastrophic (hence the term "nuclear winter") a small scale war could have an impact on the world climate, says National Geographic. Models suggest that though the world is currently in a warming trend, small-scale war could lower global temperatures 2.25 degrees F for two-to-three years following war.
In more tropical areas temperatures could fall 5.4 to 7.2 degrees F.
...even a small exchange of nuclear weapons--between 50-100 Hiroshima-sized bombs, which India and Pakistan already have their in arsenal--would produce enough soot and smoke to block out sunlight, cool the planet, and produce climate change unprecedented in recorded human history.
In addition, the extreme weather caused by even a mild nuclear winter would have a tremendous effect on crops and famines, including creating a 10 percent global decrease in precipitation, according to National Geographic. The soot could also cause tremendous harm to the ozone layer, allowing more ultraviolet rays to reach Earth.
The cons seem to outweigh the pros in the event of global cooling caused by even a small nuclear war.