The paper cited here is from a U of Arizona professor who previously won a MacArthur "genius" grant, and develops the optics for some of the largest telescopes in the world. Not a quack. Harvard has a Geoenigineering department. Smart and credible people are working this problem out. We should give them our attention, money, and talents. The paper in this post lays out a plan to reduce climate change for under 0.5% of world GDP in 2006. The price of launching weight into space has plummeted in the 15 years since this paper was written.
If you're worried about unintended consequences of geoengineering, then contribute to reducing risk by helping to develop AI. Then we'll be better able to model its effects and mitigate risk through increasingly accurate simulation. We need to tell people to study materials science or something that will actually help if they're concerned about the climate.
Climate Fatalism is so mid.