Of course, America could also be the first — again — to push the button. As North Korea threatens to launch missiles into the waters off the coast of Guam, a US territory that’s home to 160,000 people and a large US military installation, President Donald Trump and his advisors are considering a preemptive strike. Such a strike could use highly targeted nuclear weapons to take out North Korea’s underground missile sites.
Adam Liska, a professor of both biological systems engineering and agronomy at UNL, and co-author of the report, said in an email that such a strike would require “earth-penetrating” nukes like the air-dropped B61-11 and B61-7 warheads, both with payloads of 1.2 megatons. BY comparison, the atomic bomb dropped on Hiroshima in 1945 was only 15 kilotons (1 megaton equals 1,000 kilotons).
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The question asked by the UNL study is: What would be the environmental cost of deploying one or more 1.2MT nukes? If a US pre-emptive strike were successful, it could cripple North Korea’s ability to retaliate, meaning the immediate damage would be contained to the Korean peninsula. That’s far from the world-ending scenario most of us associate with nuclear war, but it could still be calamitous.
The UNL study based its damage estimates on existing nuclear war simulations for a contained regional conflict. In those simulations, the assumption was that 100 15-KT nuclear warheads would be detonated, creating a fireball that oxidizes everything within in a 1,300 square kilometer (502 square mile) radius of urban and developed areas, including people, plants, forests, buildings, fossil fuels, asphalt, plastics, etc. To burn up the equivalent area with 1.2MT warheads, you would only need to use three earth-penetrating B61-11s.
The violent destruction of all of this carbonaceous material would launch 5 million metric tons of black carbon into the atmosphere, blocking out enough solar radiation to drastically lower global temperatures and significantly decrease rainfall for years. The study estimates that global temperatures would reach 1,000-year lows in the short-term and not return to normal for 25 years. In monsoon regions, annual rainfall could drop by 20 to 80 percent, according to the study. Growing seasons would shrink and agricultural production would dry up, leading to a global “nuclear drought” and resulting famines that could claim a billion lives.
“As long as conventional nuclear weapons are prevalent, the breadth of existing research indicates that the question is not whether a nuclear drought can occur, but what factors increase its probability of occurring and what actions can be taken to mitigate the potentially devastating global impacts,” the UNL paper concludes.
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It’s important to note that those damage estimates were based on the destruction of an urban and developed area. A targeted strike in the mountainous regions of North Korea would burn up far less material, resulting in lower levels of black carbon. But the calculations are useful when considering the disastrous impact of even a “limited” nuclear skirmish in India or Pakistan, the region that political scientist Tyler White believes is the most likely to go nuclear.
Interestingly, climate change is one of the key forces that’s increasing the probability of a nuclear exchange between India and Pakistan. The two nations have fought three wars over the Kashmir region, which is the source of all major rivers flowing into Pakistan. With rising global temperatures, agricultural land is drying up across the region, making water insecurity a major concern.
“India and Pakistan have huge populations that are under stress and climate change is a huge stressor,” said White. “Climate stress can lead to war.”
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