[UPDATE: Heh, a day after I wrote my post, this appears in the Guardian] Perhaps unbeknownst to them, Roger Pielke Jr. and Joe Romm agree that population is not an important variable to the climate change equation. There's a related issue that Roger doesn't address in his post, when it comes to coupling population with climate advocacy: religious blowback. If you're someone that believes all constituencies need to be engaged in tackling global warming, then you don't want to needlessly antagonize millions of evangelicals, many who in recent years have become concerned about climate change, thanks to folks like Richard Cizik. As Cizik has explained to me several times, conservative evangelicals have an instinctual suspicion of environmentalist agendas largely because of the population issue. Never mind that mainstream enviros don't go down this road anymore. The impression remains. Now as Roger points out in his post, family planning is not population control, but in the minds of many Christian fundamentalists, it's one and the same. My point is this: if you're a climate "realist," you need to recognize that you run the risk of alienating a huge demographic (and important ally) if you play the population card. The evangelical frame into the climate change debate is much different than a secular green frame. If you're a smart, secular climate advocate, it doesn't matter if you hail from the Richard Dawkins or PZ Myers camp, the same way it doesn't matter if you're a liberal activist and you'd never vote for Lindsey Graham. What should matter to climate advocates, above all, is widening their tent. An initiative that links reducing greenhouse gases with population control measures is bound to keep a very important sector of the American public from visiting that tent.