The Icelandic Volcano eruption story is here. Notice how many times the authors of this article indicate the effect such a thing is likely to have on climate. In fact, Levitt and Dubner were excoriated for suggesting we pay some money to do this sort of a thing on our own – seems like Mother Earth beat them to it. Of course, it would take several eruptions like this to have a meaningful effect. One fear I have is that when we see two or three more years of a steady temperature (as we have for a decade now), people will simply say, “well, it would have gotten hotter were it not for the Icelandic eruption.” We’ll never really know.