I largely agree with what Ryan Avent is saying here—the appeal of geoengineering solutions to global warming is largely illusory. That controlling carbon emissions is hard is obvious because there are real proposals on the table to do so, leading to real pushback, real multilateral negotiations, real compromises, real problems, etc. Relative to that, a hypothetical geoengineering scheme can be made to look pretty good. But you have to compare like to like. On international coordination, for example, it’s actually a lot easier for me to imagine China agreeing to binding emissions targets than to imagine China agreeing to let the United States conduct a doomsday weather control machine or us agreeing to sit idly by while China launches a satellite capable of blotting out the sun.
On a non-insane level, the idea of trying to build machines that suck CO2 out of the air and then somehow store it is pretty clearly worth researching. That said, trees already do this quite well and our tree-planting technology is fine. Rather than wait around for the hypothetical “artificial trees” of the future why not just plant more trees? It seems to me there are lots of places in America where trees could be growing but aren’t.
Which comes around to the overarching point that the term “geoengineering” often obscures more than it reveals. There’s a world of difference between offering financial incentives for people to build high-albedo roofs and building a miles-long hose to pump sulfur into the upper atmosphere. Do I get to be a bold contrarian thinker if I propose that surface parking lots should have more tree cover? Somehow it seems I don’t. But it makes much more sense to focus on practical deployments of proven technology (trees, white paint) than on trying to dream up the most fantastical possible solution.