Back in early August, I noticed a rather curious claim from Roger Pielke Sr. [insertions and emphases mine]:
We are, also, of course, at the time of the year in Russia with the warmest temperatures at these levels. [ed. note: i.e. “summer”] However, the absolute temperatures will soon start to fall both in Russia [ed. note: i.e. “winter”] and globally (i.e. we will have global cooling for the next 6 months or so) . If global warming (as diagnosed by an annual global average) was a more-or-less linear accumulation of heat, than the heat accumulated (as a positive temperature anomaly) in the lower troposphere must remain in the coming months. The regional anomaly in Russia, of course, can be displaced to other locations.
We will follow this analysis in the coming months, as we have a valuable test as to whether global warming in the annual average is progressively continuing or if natural (or human) climate forcings and feedbacks provides higher than average cooling in the coming months.
Let me set the stage.
At the time, Moscow’s environs looked like a holocaust, Pakistan was flooding, we were experiencing record temperatures globally, and people finally seemed to be recognizing that leaked emails and some IPCC errors didn’t mean that global warming was a hoax.
The 12 month record global temperatures were reached in no small part due to an El Niño boost atop the underlying anthropogenic warming signal. But already, we had transitioned to La Niña conditions and forecasts we being made for the La Niña to prevail for at least several months . And just as El Niños bump the globally averaged temp up, La Niñas bring them down.
ENSO is the one of the dominant drivers of interannual temperature variance. This has been and remains true even as anthropogenic warming marches on (though ENSO’s relative importance might somewhat decrease as unchecked warming progresses). We should expect a significantly strong La Niña to not only temporarily counterbalance, but even overwhelm underlying the anthropogenic warming signal. This in no way means that the planet will not continue to warm to a higher equilibrium due to the build up of GHGs in the atmosphere.
Clearly, a La Niña could push global temps down from their record highs, and if strong enough, would even push them temporarily below average. It happened in 2008, after all, and yet here we were in August 2010 with record temperatures. Pielke hadn’t claimed that 2008 represented a falsification of global warming (to the best of my knowledge). Yet in August he was saying something suspiciously like that. Was I misreading him? It was such a blatant cherry-picking excercise I thought I must have somehow misunderstood him. I sent a few emails noting his post [one saying: “The developing La Niña is almost sure to cause ‘higher than average cooling in the coming months.’ Who [knew] how easy it was to falsify this silly “global warming” nonsense?”] and more or less forgot about it.
Then I’m pointed to this post, in which Pielke not only reiterates his intent to cherry-pick the La Niña as evidence against warming, but adds the twist that it will somehow be positive evidence for some as-of-yet-undiscovered negative feedback in the climate system:
What is very interesting in this latest analysis is that almost the entire globe has above average lower tropospheric temperatures. If this persists while we are in a La Niña pattern (when we expect cooling) it will provide strong support for those who expect a long term warming to occur as a result of the accumulation of greenhouse gases in the Earth’s atmosphere. On the other hand, if the temperatures cool to average or below average over large portions of the globe, this would indicate that the climate has a self regulation which mutes temperature excursions.
I couldn’t believe it. ENSO will continue to drive short term variation atop the underlying anthropogenic warming signal. The multivariate ENSO index is showing this current La Niña to be stronger than the one from 2008.
If it persists (currently forecast to do so at least until Spring 2011), we can and should expect a drop to average or possibly even below average lower troposphere temps for a little while. And if/when we do, that is hardly a falsification of enhanced greenhouse warming or positive evidence of some sort of self-stabilizing climatic negative feedback. If we don’t (although it might be unexpected) that isn’t in and of itself “proof” of anthropogenic warming. (Were it actually true, by Pielke’s own standards we’d already have “proven” global warming, as La Niña conditions first developed in May-June and global temperatures have remained above average for the interim five months.)
I’m open to the possibility that I’m simply reading Pielke wrong. It’s certainly possible. But I’m also a little hesitant to unduly extend the benefit of the doubt to someone who claimed that Arctic sea ice conditions over the past several years show there has been no recent decline. So rather than wait until a neutral or below average UAH lower troposphere temperature reading, I thought I might as well get out in front of this one.
UPDATE: Like clockwork.