Has global warming stopped? I'm glad you asked...

The question comprises the headline of an essay in the New Statesman from David Whitehouse, a former BBC science editor and astronomer ;;;; not someone easily dismissed as a psuedoskeptical crank. His argument getting a lot of traction, and I've even been asked "is this legit?" The answer is ...


Whitehouse, of course, says it has stopped. Otherwise, he wouldn't have asked the question. But the flaw in his argument appears early in the essay:

The fact is that the global temperature of 2007 is statistically the same as 2006 as well as every year since 2001.Global warming has, temporarily or permanently, ceased. Temperatures across the world are not increasing as they should according to the fundamental theory behind global warming

"Statistically" the same? This is a dangerous and perhaps even disingenuous statement. Statistics are, generally speaking, a limited number of samples of a finite number of real things -- voters in an election, for example. You could argue that the thousands of thermometers climatologists use record only a sampling of the infinite number of places where temperature could be measured, but that's sophistry, not science. It implies that climatologists have been failing to be honest with us each time they tell us how warm a year was compared with other years. And that's insulting.

Furthermore, "statistical significance" is another way of talking about the degree of precision of your measuring technique, Fortunately, the thermometers are actually pretty darn precise, far more precise than the variation in temperature from one year to the next. Whitehouse says it's "an observational fact" that the earth has not warmed since 1998. That's not true (see below). But what's really odd is, according to Whitehouse's own logic, there's no way we can know one way or the other whether it has stopped, because of the noise in the "statistics" hides any real trend. You can't have it both ways, Dr. Whitehouse.

As for the observational data, actual, real-world temperature records (data, not statistics) show an inexorable warming throughout most of the 20th century, one that continues into the 21st. NASA chief climatologist Jim Hansen, for example, would find the idea that there has been no measurable warming since 2001 quite at odds with the data. He wrote recently:

Through the first 11 months, 2007 is the second warmest year in the period of instrumental data, behind the record warmth of 2005 ... The global mean temperature anomaly, about 0.6°C (about 1°F) warmer than the 1951-1980 mean, continues the strong warming trend of the past thirty years that has been confidently attributed to the effect of increasing human-made greenhouse gases. The six warmest years in the GISS record have all occurred since 1998, and the 15 warmest years in the record have all occurred since 1988.

Warming has not stopped.

Whitehouse may once have been a decent scientist and author. I have no idea. But on the subject of climate change, his objectivity has already been found wanting -- creating a fuss last year when the Royal Society dared criticize the anti-science activities of ExxonMobil, for example.


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Neither Hansen's nor Whitehouse's claims are inconsistent with the data. If there has been an increasing trend that is slowing down or stopping, as Whitehouse seems to say, a new 2nd order statistic, as claimed by Hansen is not in the least surprising.

"Statistically the same as" is so vague as to be meaningless. This is a testable claim, using bioequivalence techniques or using changepoint models. I doubt the data support that using the first method, but they do using the second.

The Denialists-of-Convenience are ignorin' the great big elephant on the planet, Surely, if they can number-crunch an array of tenth-of-a-degree observations and come up with a basket of warm fuzzies from those able computers, they can take on the Big Pachyderm. Just calculate the BTUs over the satellite images of arctic ice-melt with time.
While yer runnin' that one tiddle up a heat transfer dynamic for the Atlantic "Franklin Current" will ye?
C'mon and do somethin' instead o' bitchin'!

When each year happened to be hotter than the last, this increase was decried as a mere statistical anomaly, a coincidence that happened to be consistent with the claimed general trend. (Which is not an unreasonable claim.)

But now that the years have happened to be similar, there seems to be a little consistency problem. Does this twit acknowledge that these could be merely a coincidence, noise in the signal that doesn't contradict the longer-term trend? No, he does not.

Instead, it's proof! proof! proof! that global warming is no longer a problem. The trends over decades? Irrelevant! We have more than one year in a row with similar weather patterns, therefore, the warming has stopped!

Sometimes, there's nothing like a good old-fashioned blanket party.

By Caledonian (not verified) on 26 Dec 2007 #permalink

Chaotic Utopia has a quite interesting post on Greenland. Do people need to wait for the last days of ice melting to get convinced? I can think of several results including a huge tidal wave and tectonic plate disturbance. Meanwhile the melting could be a cooling factor (I'm not sure how it works). Unfortunately, I meet people every day who won't see they are handling something wrong until after it has broken down. I'm trying hard to avoid cynicism but getting depressed about humanity is also of no help.

Karmen has a real good post on her blog, Chaotic Utopia about lots of proof that Greenland is melting. Hasn't stopped or even slowed down!
Dave Briggs :~)