This new Nature paper on solar geoengineering and crop yields is quite interesting, although some of the coverage of it has not been great: nature.com/articles/s4158… /1
The basic argument of the paper is that future global warming is expected to be bad for crop yields worldwide and those harms might be difficult to minimize through solar geoengineering alone. /2
Why? If we put aerosol particles into the atmosphere to reflect more sunlight into space, that could slow the rise in global temperatures — good for crops. But it could also lead to less sunlight hitting Earth — bad for crops. Those two effects, the study says, balance out. /3 
Now, this clearly isn't an argument *against* using solar geoengineering to mitigate global warming. Geoengineering might still have other benefits elsewhere (say, reducing heat waves or protecting glaciers). Or risks! The *only* contention here is that it's neutral for crops. /4
That said, this paper isn't the last word on the crop question. It relies on data from past volcanic eruptions, which are not a perfect analogue for most geoengineering ideas. See this thread for other critiques: /5
What's more, the paper doesn't look at how solar geoengineering might affect things like drought frequency — it's possible there could be additional benefits for crops there. Or maybe additional risks! Can't say for sure. /6
Anyway, @GernotWagner has the most accurate headline for this study, though sadly it's not very sexy: "Important new research points to importance of more research." Some of the other headlines have been bad or outright misleading, like so: /7
Obviously there are exceptions. @carbonbrief always does a fantastic job of coverage and I'm sure I've missed other good stories: carbonbrief.org/solar-geoengin… /8
(fwiw, I'm undecided on solar geoengineering myself. We've committed the planet to so much global warming at this point that it seems crazy not to at least consider it in conjunction with emissions cuts. But there are still soooo many questions. /end)
