Nuclear war would completely reverse the effects of climate change, and then some, new research has found.
If the US and Russia used up their nuclear arsenals, the resulting carnage would blow enough soot into the atmosphere to blacken the skies for seven years, say US scientists.
This would block the sun, dropping the Earth's average temperature by 8C and causing a nuclear winter.
"Current nuclear arsenals used in a war between the United States and Russia could inject 150 teragrams of soot from fires ignited by nuclear explosions into the upper troposphere and lower stratosphere," their paper, published Friday in the Journal of Geophysical Research: Atmospheres, reads.
That's 150,000,000,000kg of soot.
"The global hydrologic cycle would become far less active, with a reduction in summer monsoon precipitation and a significantly reduced growing season. Impacts on human society would be devastating."
It would take seven years for the first signs of sunlight to return, and a decade to return to normal.
"Nuclear winter, with below freezing temperatures over much of the northern hemisphere during summer, occurs because of a reduction of surface solar radiation due to smoke lofted into the stratosphere... after two weeks it drifts into the southern hemisphere."
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The upside? It won't be as bad as when the asteroid hit 66 million years ago, finishing off the dinosaurs.
"An injection of 150 teragrams of black carbon would be a far greater aerosol loading than wildfire contributions or any volcanic eruptions from the past 100 years, but would be orders of magnitude smaller than injections of black carbon into the atmosphere 66 million years ago when an asteroid impact caused much of the biomass on Earth’s surface to burn, resulting in a mass extinction event."
Still, the researchers warn, politicians and generals should have "a full understanding of the grave climatic consequences of nuclear war and act accordingly".
"A full-scale nuclear attack would be suicidal for the country which decides to carry out such an attack. The use of nuclear weapons in this manner by the United States and Russia would have disastrous consequences globally."
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The latest research was carried out using state-of-the-art climate models, improving on similar studies in the past.