Sorry for the late reply. Yeah, I'm skeptical of geoengineering climate too, though mostly for the standard ideas of putting a particulate layer high in the atmosphere to reduce sunlight in order to counter global warming. That is potentially so dangerous it could go wrong in terrible ways, quite apart from giving greenhouse gas polluters a rationale for continuing, so that we then end up addicted to the process. And you know what happens when an addict has to go without their drug for a while because of circumstances... say, a smoker who has to take a long flight (terrible temper), or an alcoholic who is unable get alcohol for a day (death through convulsions). In the case of such a sunshield failing for some reason we would be suddenly roasted, worldwide. And that's ignoring the risk of too much creating a mini-ice-age.

So, yes. Most talk of geoengineering climate I find quite disturbing.

However I have to say that the idea of dropping small chunks of ice onto the Sahara appeals to me. They could be sized so that they never reach the ground, but melt and evaporate in the atmosphere, to create rainclouds. It might also reverse the gradual loss of hydrogen from Earth into space. Our planet is gradually drying out -- not as fast as Mars did, without a strong magnetic shield to protect its atmosphere -- but it is, very, very slowly.