Hooray! El Nino is back!

Posted on July 13, 2009

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elnino2009It’s probably selfish of me to be reasonably pleased that el Nino conditions have reappeared in the Pacific. El Nino means real hardship for real people in Australia, Indonesia, and India, and some will lose their livelihoods and/or lives as a result of the droughts that come with el Nino. Similarly, el Nino tends to produce more eastern Pacific hurricanes, stronger storms in the U.S. that could cause flooding and, as a result, the death of innocent people. So on one hand, it’s morbid of me to be happy for the return of el Nino.

On the other hand, complaining about el Nino is about like complaining about a volcano that erupts and destroys a village – it’s sad that the village was destroyed, but the eruption is a great source of new data for vulcanologists around the world. And it’s not like humanity has control over the weather, so worrying about it, or feeling guilty about a little pleasure from it, is pretty much pointless.

So I’m feeling a little selfishly happy about el Nino right now. After all, it’s like a shiny new toy with which climate activists get to beat up climate disruption deniers.

To explain my small joy, a little historical context is probably in order.

1998 was the hottest year on record because of an extraordinarily powerful el Nino that heated up the entire planet dramatically. But because it was so hot, climate disruption deniers have been using it as the starting point from which they claim, wrongly, that “the global temperature has been cooling for a decade now.” This false claim was strengthened by the lucky coincidence that 2008 turned out to be a la Nina year, when the global temperature dropped significantly. Climate disruption deniers then took advantage of an unfortunate fact of least-squares linear trend estimates – they’re VERY sensitive to endpoint variation, especially in short, noisy datasets. And not only is global temperature noisy on a monthly and yearly basis, but ten years is a woefully short amount of data. And don’t even get me started on Joe D’Aleo’s, Lord Monckton’s, and Ross McKitrick’s 5-year “trend” from 2003 to 2008 which, conveniently enough, has another el Nino to la Nina transition.

So now, with a new el Nino heating up the summer and autumn global temperatures by some as-yet-unknown amount, climate disruption scientists and activists have their own convenient endpoints to the data. 1999 was a la Nina year, after all, and 2009 is an el Nino year, so any trend calculated from 1999 to 2009 will be huge, given that global temperatures for July through December are significantly warmer on average than January through June. It’s not outside the realm of possibility that 2009 could be warm enough to turn the supposed “cooling trend” into a “warming trend” all by itself. And that’s the first reason I’m happy about a new el Nino.

Of course, we’re talking weather here, not climate, and the exact same statistical tools that I and others use to debunk the bogus cooling trends touted by deniers could be used against any climate scientist who touts a hot 2009. But that brings me to the second reason I’m happy about el Nino – I’m actually looking forward to climate disruption deniers screaming “a hot year in 2009 is only weather, the cooling trend since 1998 is a real trend!” Because in return, I get to call the denier a hypocrite.

Math is math, after all. If the data statistics says that there’s too much noise in the data to extract a meaningful trend from 1998 to 2008, the the same will almost certainly be true from 1999 to 2009. And as a result, any denier who looks at the 99-09 trend and says “that’s just weather, not climate” or “the trend has endpoint problems that make it inaccurate” or even “you cherry-picked your endpoints” will immediately be revealed as a liar and a hypocrite.

Of course, any climate scientist who actually does tout the 1999 to 2009 “warming trend” but who complained about the 1998-2008 “cooling trend” would also be revealed as a hypocrite.

[I checked the trends using HadCRU3v data, and these are the results for 1998-2008 vs. 1999-2009, if the average for the first half of 2009 ends up the annual average temperature. 2008 to 1998 was a trend of -0.017 deg/dec with an autocorrelation adjusted standard error of 0.189. This means that there’s 10x more noise than signal, and so the trend could be anywhere between +0.172 and -0.206 deg/decade. The 1999-2009 (to date) trend is about 0.043 deg/decade with an autocorrelation adjusted standard error of 0.099. This means that there is only 2x more noise than signal for 1999-2009, and the real trend range could be anywhere between +0.142 and -0.056 deg/decade. There’s still more noise than signal, though, so no firm conclusions can be drawn about the trend from such a short period/limited sample size.]

So I’m happy about el Nino this year. I’d have been happier if it had come on strong earlier, so that the news could have had horror stories of droughts just in time to scare the House into voting on a much stronger Waxman-Markey bill than what actually passed, but better late than never. At least el Nino arrived before the Senate got going on a climate bill. Maybe el Nino can do what an army of environmentalists and climate scientists couldn’t – convince the Congress to serioulsy address climate disruption instead of playing politics.

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