1. SRM will reduce efficiency of equatorial solar but minimally effect solar in northern climes. Like, less than 5% reduction. Pretty good trade off for stabilizing temperatures.
SRM from lofting sulfur or calcium only lasts about a year. It has to be done yearly. So, no long term effects, for better or worse.
2: We will fry the planet long before running out of fossil fuels. There is a lot left.
3: we absolutely can and must try geoengineering at small scales before scaling up. It isn’t a binary phenomenon. Every time there is a volcanic event, we get a natural experiment.
1: it would make solar less effective so we'll have a harder time reducing our fossil fuel usage
2: fossil fuels will actually run out at a certain point, and we'd still be stuck with a dim sun but without the warming effects of fossil fuels
3: engineering is a process of trial and error, and we can't afford to try this and fuck it up