If media coverage is your measure, climate Scientist James Hansen scored big today with his paper in the Proceedings of the National Academy. Earth Headed for Warmest Temps in a Million Years was the ABC news headline. I love it that they called him “the U.S. government’s top climatologist.” And you’ve got to love a PNAS paper going out of its way to trash Michael Crichton, a trashing Crichton richly deserves. He’s been misrepresenting Hansen’s work, and there’s a bit of exquisite justice seeing him taken down in the peer-reviewed literature.
But the most interesting bit for me is the part of the paper that doesn’t seem to be getting much play – its discussion of El Niño.
El Niño matters because of its significant effect on climatological variability worldwide – droughts in Australia, wet across the southern U.S., etc. And in terms of climatological impact on humans, it’s variability that bites you.
In a previous draft of the paper circulated for comment, Hansen made a tentative forecast of a “Super El Niño” this year. That was pretty far out of the mainstream, for which Hansen was criticized by me and others. That is gone from the paper’s final version. But Hansen does lay out his belief that global warming increases the likelihood of stronger El Niños – “Super El Niños”, as occurred in 1983 and 1998.
I’m not qualified to substantively evaluate Hansen’s argument. The models are all over the map on this, and there’s a body of literature that seems to point in the opposite direction: a link between a warmer planet and more La Niña – the opposite of El Niño, with opposite regional climate effects. Maybe that’s why it’s reasonable not to give this part of the paper too much media play. But I think it’s the most important bit, because understanding the effect of global warming on El Niño, and therefore on issues affecting regional variability, is critical. So I applaud Hansen for sticking his neck out on this.