In general, this kind of thing has big issues at aren't really resolved

• You need to continue doing it for longer than civilizations last. People don't really have a good track record of that kind of thing.
• We end up with a smaller pole-to-equator temperature gradient, with real impacts on weather
• These changes can alter rainfall patterns in ways that might cause significant food supply issues in some countries. This creates a governance problem. (eg: should China nuke India if the changes needed to prevent lethal heatwaves in India result in famine in China)
• It does nothing about ocean acidification, so we still end up losing a big chunk of marine ecosystems
• Addressing climate change this way means we don't get any of the co-benefits of reduced air pollution we would otherwise get from phasing out fossil fuels
• Probably other stuff we don't know about because it's not well studied