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Lightning Can Trigger Nuclear Reactions, Creating Rare Atomic Isotopes (sciencemag.org)
sciencehabit shares a report from Science Magazine: Rare forms of atoms, like carbon-13, carbon-14, and nitrogen-15, have long been used to figure out the ages of ancient artifacts and probe the nuances of prehistoric food chains. The source of these rare isotopes? Complicated cascades of subatomic reactions in the atmosphere triggered by high-energy cosmic rays from outer space. Now, a team of scientists is adding one more isotope initiator to its list: lightning. Strong bolts of lightning can unleash the same flurry of nuclear reactions as cosmic rays, the researchers report in Nature. But, they add, the isotopes created by these storms likely constitute a small portion of all such atoms -- so the new findings are unlikely to change the way other scientists use them for dating and geotracing.
Because the effect of cosmic rays on 14C production in the atmosphere has been directly measured, and while there is a measurable shortfall there, the production from lightning can't amount to very much or the amount being produced from cosmic rays would be far off the observed atmospheric concentration. There's also a good historical record of 14C concentration in the atmosphere thanks to tree rings, glacial ice cores, and corals going back thousands of years. Example. Other than the mess made by 14C production since ~1945 thanks to atmospheric nuclear bomb testing, those concentrations jive with what would be expected primarily from the cosmic ray production. If lightning contributes too, it would have to be a relatively small proportion or the equilibrium achieved between 14C production and decay would be at a much higher concentration.
It's also worth noting that the gamma-ray production from lightning, which is associated with the process producing 14C, is only observed for the most extreme lightning events, detected at rates of around 50 per day world-wide versus the millions of individual lightning strikes that presumably aren't strong enough.
Well, we're talking about roughly 1.4 billion flashes per year, and they're not evenly distributed around the planet. As to the power of each flash, I don't know how you could get good readings and keep the sensors intact... only 10 to 20 percent of the bolts reach the ground so we need disposable balloons or something to get actual voltages. Getting amperes or wattage has to be an estimate. So, now we know that rare isotopes created... but is lightning also creating common isotopes? If so, how much and what kinds? There could be WAY more going on then these first clues indicate.
More on lightning here:
http://www.aharfield.co.uk/lightning-protection-services/about-lightning
and here:
https://www.treehugger.com/natural-sciences/where-world-does-lightning-strike-most.html
and here:
http://geology.com/articles/lightning-map.shtml
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You don’t need to be a nuclear engineer to know all that - you only need to be somewhat technically literate.
I will quibble with part of your comment though. Nuclear reactors do not pollute the atmosphere during routine operation. There are circumstances where reactors have released (usually small amounts of) radioactive material into the air - these things are well-studied. Also, the potentially bigger environmental concern raised by some has been the affect of increased water temperature on fish and other aquatic life due to the release of cooling water into rivers and such. Regulation, combined with monitoring, helps ameliorate this.
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