[Gravityloss]

One problem with geoengineering is that it doesn't neatly negate effects of increased CO2 - it's hard to predict exactly what will happen. If we triple CO2 and install space glasses that refract sunlight so that it misses the earth, what will happen? Maybe the refraction and CO2's radiative forcing will cancel itself at some latitudes on some days. But in many other places and climate conditions, they won't.

For relative climate stability, by far the technically simplest and most straightforward way would be just to stop burning coal and stop projects like tar sands and oil shale.