Ever since a glowering Alan made that list of all the ways geoengineering could go wrong, this has been the one that perhaps concerns him most.

A Princeton professor went around and asked people, "What's the worst thing that could happen if we did this?" And the answer to his poll was global nuclear war because different countries would not want their climate changed in order to make another country's climate better.

Still, Alan Robock, with his list, is skeptical countries can ever come together and agree on rules for this technology to save us from climate change.

It's been 31 years we're trying to solve the global warming problem, and the countries of the world can't even agree on that.

And so how could they agree on this very sort of radical kind of so-called solution to climate change?