I'm in the middle of reading a great book on geoengineering, Oliver Morton's <i>The Planet Remade</i>. Engagingly written and comprehensive; I recommend it highly. From the introduction:<p><i>If the world had the capacity to deliver one of the largest nuclear power plants ever built once a week, week in and week out, it would take 20 years to replace the current stock of coal-fired plants (at present, the world builds about three or four nuclear power plants a year, and retires old ones almost as quickly).</i><p>Morton goes on to make the case for considering geoengineering, and for ramping up research on it. I don't know that I can do justice to the argument in a short summary, but one key point is the extent to which we're already doing it in an unplanned way. We all know about all the carbon dioxide we're putting in the air, along with other greenhouse gases -- nitrous oxide, for example -- but there's also the massive amount of reactive nitrogen we're creating, mostly for fertilizer. We all know about the massive local environmental effects of burning coal, but there's also some evidence that coal smoke has a cooling effect; changing from coal to nuclear may actually worsen warming in the short run.<p>I was favorably disposed toward geoengineering before I got the book, so I can't claim to have been won over, but there was an awful lot I didn't know about it -- for example, how the various approaches would affect different regions of the globe differently, and how those effects could be adjusted to some extent, though not optimized for everyone simultaneously.<p>Again, I highly recommend it.