There's an intriguing geoengineering discussion going on here: PRI has brought in the economist Scott Barrett of Columbia, who thinks the economics of geoengineering are just going to be irresistable to most countries, especially when compared with the economics of carbon emissions cuts. That's a scary thought, although not exactly a surprising one. You can read Barrett's academic paper on the topic here, and head over here to join in the dialogue it has occasioned. Meanwhile, we're finishing up the next Point of Inquiry, and I promise my intro isn't as soapbox long this time. (Hey, I'm learning.) Eli Kintisch was a great guest, so tune in tomorrow....