approaches to geoengineering; they all have three things in common. One, they’re relatively cheap compared with the scale of the problem, requiring up-front capital costs of less than $10 billion and minimal operating expenses. Two, the effect on clouds lasts for a week or so, so we could use them as long as we needed to and then stop with no long-term impacts. And three, whatever technical problems these ideas might face are nothing compared with the political hurdles they’ll definitely face.
