What if climatologists reversed the null hypothesis?

ResearchBlogging.orgKevin Trenberth’s latest paper, which appears in Wiley Interdisciplinary Reviews: Climate Change, is uncharacteristically and refreshingly blunt right from the first few words of the introduction:

Humans are changing our climate. There is no doubt whatsoever. There are arguments about how much and how important these effects are and will be in future, but many studies (e.g., see the summary by Stott et al.1) have demonstrated that effects are not trivial and have emerged from the noise of natural variability, even if they are small by some measures. So why does the science community continue to do attribution studies and assume that humans have no influence as a null hypothesis?

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FTL neutrinos and climate change deniers (or why I call the latter PSEUDOskeptics)

Among the very best of the science-oriented blogs I try to read regularly is Tom Levenson’s Inverse Square Blog. Tom, who teaches science journalism at MIT, isn’t a climatologist, but whenever he writes about climate science or politics, it’s usually worth a look.

Apparently, the folks at Scientific American agree, and they recently invited Tom to contribute a guest post to the magazine’s blog site. It’s primarily about the recent kerfuffle over the possibility that neutrinos might be able to travel faster than light, and a bit on the lengthy side, but he does manage to work climate in there, so let’s skip to that bit and run with his central theme, which is:

understanding what we do know, and then engaging the challenge of a new result in that context.

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Fighting the “he said, she said” cowardice

Don’t get me wrong. I love NPR. I listen to it for at least four hours a day. But lately I’ve found the network’s embrace of “he said, she said” journalism a little too difficult to swallow. This morning’s report on censorship of a scientific report commissioned by the Texas Commission on Environmental Quality isn’t perhaps the most egregious example, but it does concern climate change, so it’s worth examining.

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BEST paper in the urban heat island effect category

There’s this notion among the climate denial community that somehow the entire professional climatology community has overlooked an obvious flaw in the science behind anthropogenic global warming. Their hypothesis is that too many of the thermometers used to record temperatures over the last 200 years have been located in or near cities, and so have produced a warming bias produced by the waste heat generated in urban areas.

It sounds plausible. The problem with the notion, of course, is that it’s so obvious a potential bias that climatologists long ago learned to take the “urban heat island” effect into account. Still, the idea persists, and so a bunch of still-open-minded-despite-reams-of-solid-evidence-scientists, known collectively as the Berkeley Earth Surface Temperature (BEST) project, and all but one of them new to the field, decided to conduct their own independent analysis of the data that NASA, NOAA and HadCRU say shows unequivocal evidence for global warming.

Today, that team released its findings. Can you guess what they found?

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Surprise! Clouds have a cooling effect

Drawing attention to misinformed pseudoskeptical analyses of peer-reviewed climatology studies is usually counterproductive. But in this case, it’s worth mentioning because the author makes such a common mistake that exploring the error might actually help shed light on the why so many people are easily led astray.

ResearchBlogging.orgThe offender is Anthony Watts, who is arguably (depending on how much weight you assign to blog popularity polls) among the most influential anti-science bloggers out there. His error was to confuse (or conflate, to use a fancier term beloved by social scientists) a direct effect with a feedback.

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Fit to be tied

So, 2010 is a statistical tie for warmest year on record. This from NASA’s GISS and NOAA’s NCDC. Some AGW refuseniks might cling to the fact that the year just past was 0.018 degrees Fahrenheit cooler than 2005, but then you’d know they never bothered to take a stats class. As the GISS press release puts it:

The record temperature in 2010 is particularly noteworthy, because the last half of the year was marked by a transition to strong La Niña conditions, which bring cool sea surface temperatures to the eastern tropical Pacific Ocean.

We’ve also just come out of an unusually long “solar minimum,” during which sunspot activity has been next to nil, a condition that otherwise could be expected to depress temperature on Earth.

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[Graphic from a New York Times story.]

The interesting thing to me is that this is just what GISS chief James Hansen and many others have been predicting for pretty much the entire year, suggesting that our understanding of the global climate system continues to improve.

The latest prognostication from the usual suspects involves the assumption that a return of the warmer, El Niño counterpart of the same cycle, and the possible return of a more active sun, will help make 2011 warmer still.

The annual report from the other side of the Atlantic isn’t out yet, although there’s a good chance it won’t put 2010 quite at the top of the list, because it excludes much of the northernmost reaches of the Arctic due to a lack of observations. NASA, by comparison extrapolates from the most northerly stations that do supply temperature data. And this year it was the Arctic’s unseasonable warmth that helped make 2010 as hot as it was. In the Southern Hemisphere, for example, 2010 was only the sixth warmest, and the global ocean temperature managed to reach third place.

Regardless with what the Brits report, it has now been 34 years in a row that the global temperature has been warmer than the 20th century average.

Explaining global cooling

The invaluable pseudonymous Tamino has a brilliant explanation of the causes of the “global cooling” trend in the mid-20th century. There’s nothing new, except the clarity of the writing. So if you’ve ever been stumped by a skeptic who suggests that anthropogenic climate change theorists can’t explain why the planet cooled for the three decades following the Second World War, bookmark this post.

Just a tease:

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Matt Ridley and the Holocene Optimum

If the title of Matt Ridley’s new book, The Rational Optimist, sounds a little familiar, that’s because it borrows heavily from the world view of one Bjorn “The Skeptical Environmentalist” Lomborg. Both contrarians dismiss global warming as nothing to worry about, although Ridley seems even less convinced that the planet is actually experiencing anthropogenic global warming. I don’t have time to read it — but I did manage to take a look at the kind of thinking that Ridley uses at his blog.

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