If climate change is catastrophically serious, we need to reduce the CO2 in the atmosphere and immediately switch from coal to nuclear
Even if we did that, it would still take several decades for it to have an impact. And we won't do that. If climate change is catastrophically serious, then geo-engineering would be the only effective solution. On the plus side, it is only 1/1000th as expensive as CO2-emission elimination.
When lives are at stake you mostly plan for the worst case scenario, unless you are a cynic of course.
The trouble is that doing what you suggest puts millions of lives at risk in itself. The third world already has severe energy-poverty problems without being burdened with more.