Grist's David Roberts asked me to do an overview of my thoughts on geoengineering for Gristmill. The piece -- given the title "Plan B" -- has now been posted. Here's an excerpt:

No matter what, we would have to continue with emission reductions, even if we don't work fast enough to escape serious problems. Carbon dioxide sticks around in the atmosphere for centuries; the more we add, even slowly, the longer the crisis will last. But we'd also have to decide on a more immediate strategy.

The conventional response would be to focus on mitigation, building the kinds of projects needed to lessen the very worst impacts of global warming. Even in the best scenario, we'd still see disastrous events, and many deaths; in time, however, we'd learn how to deal with the new climate. Hopefully, we'd be able to do so before too many people died from heat waves, drought, opportunistic diseases, storms, resource wars, forced migration, and the like. But make no mistake: the mitigation scenario would still be catastrophic for many around the world.

That's why the geoengineering option appeals to many: systems that cool the planet a bit over the short run could suppress many of the more disastrous effects of warming temperatures, even as we continue with emissions reductions. Geoengineering projects are generally within our current technological and financial capabilities, and most emulate well-known natural processes. The goal would be to give us time to make the social, political, economic and technological changes needed to stop building up greenhouse gases.

If you've been reading my geoengineering essays over the years, this one won't come as a huge surprise. If you're still new to the subject, however, it's a decent summary of where my thinking is at this point.