michael mann

A Review of Michael Mann's Exoneration

In the endless - and senseless - assault on Michael Mann and his famous hockey stick graph, it is generally overlooked that the graph has withstood all of the criticism and, still today, stands as a perfectly accurate picture of climate over the past millennia.

Most convincingly, its results have been replicated by other methods, using other proxies on more than a dozen occasions.

As well, however, Mann’s conclusions were vindicated in two independent reviews, the second of which, by Edward Wegman, was particularly hostile in it conception, but ultimately exculpatory. Arie Brand covered this so well in a comment to the next post that I felt compelled to reproduce his note here, for the convenience of those who are too offended by the trolls to pick through all of the excellent comments buried among the mindless criticisms.

Thank you Arie:

Michael Mann in his own words on the stolen CRU emails

With all the wild accusations flying around over the illegally obtained email correspondence from the University of East Anglia Climate Research Unit, I thought I would ask one of the scientists in the middle of the issue to provide some context.

Penn State University climate scientist, Dr. Michael Mann, whose name appears in some of the stolen emails, provided me with a run-down of the emails that involve him. His responses provide some much needed context and give you an idea of just how wildly some people have blown this story out of proportion.

What follows is quotes taken directly from the stolen emails, followed by Dr. Mann’s response:

1. “I’ve just completed Mike’s Nature trick of adding in the real temps to each series for the last 20 years (i. e. from 1981 onwards) and from 1961 for Keith’s to hide the decline.” (from Phil Jones).

Phil Jones has publicly gone on record indicating that he was using the term “trick” in the sense often used by people, as in “bag of tricks”, or “a trick to solving this problem …”, or “trick of the trade”.

In referring to our 1998 Nature article, he was pointing out simply the following: our proxy record ended in 1980 (when the proxy data set we were using terminates) so, it didn’t include the warming of the past two decades.

In our Nature-article we therefore also showed the post-1980 instrumental data that was then available through 1995, so that the reconstruction could be viewed in the context of recent instrumental temperatures. The separate curves for the reconstructed temperature series and for the instrumental data were clearly labeled.

The reference to “hide the decline” is referring to work that I am not directly associated with, but instead work by Keith Briffa and colleagues.

The “decline” refers to a well-known decline in the response of only a certain type of tree-ring data (high-latitude tree-ring density measurements collected by Briffa and colleagues) to temperatures after about 1960.

In their original article in Nature in 1998, Briffa and colleagues are very clear that the post-1960 data in their tree-ring dataset should not be used in reconstructing temperatures due to a problem known as the “divergence problem” where their tree-ring data decline in their response to warming temperatures after about 1960.

Hide” was therefore a poor word choice, since the existence of this decline, and the reason not to use the post 1960 data because of it, was not only known, but was indeed the point emphasized in the original Briffa et al Nature article. There is a summary of that article available on this NOAA site.

A Question of Framing

What a difference a year can make. While the consensus on the Hill may not have grown stronger in the interim—I’m looking at you, House Republicans—the American public seems to be increasingly wising up to the idea that global warming is, in fact, a real threat and not some nefarious liberal plot to deprive it of its God-given right to pollute.

That is the principal finding of a new survey, entitled “Global Warming’s Six Americas,” that was released this past week by the Center for American Progress. The survey, which the authors describe as an “audience segmentation analysis,” splits the American public into six distinct groups based on their level of engagement with global warming: alarmed, concerned, cautious, disengaged, doubtful, and dismissive.

The authors polled 2,129 American adults in the fall of 2008 on a variety of issues related to global warming, including risk perceptions, policy preferences, and values.

Parsing Dennis Avery's Other Dubious Claims

Dennis Avery may have done the fact-challenged (yes, again) WaPo columnist George Will one better by actually admitting he’d “misstated” that CO2 levels at Mauna Loa were declining (when they were, in fact, quite clearly rising), but the remainder of his column was so error-filled that I thought it deserved another look.

Take the first half of the piece, in which he approvingly cites Australian – and Oxford-trained – research physicist Tom Quirk to make the jaw-dropping argument that natural climate variability, and not anthropogenic activity, is to blame for elevated atmosphere CO2 levels. A quick look at Avery’s list of citations informs us that Quirk’s article appeared in a recent issue of Energy and Environment, a “peer-reviewed” journal curated by Sonja Boehmer-Christiansen, which does not inspire great confidence in its scientific rigor.

Hockey Stick Rises Again

The fabled “hockey stick” - Michael Mann's graph showing the last decade to be the warmest in a 1,000 years - has re-emerged, stronger and longer than ever.

In a peer-reviewed paper published today in the online version of the Proceedings of the National Academy of Sciences, Mann and six other scientists show that current warming is the most severe in more than 1,300 years - 1,700 if you accept still-controversial data drawns from tree rings.

Nature to Palin: "I'm Hotter Than You!"

Researchers confirm that surface temperatures in the Northern Hemisphere were warmer over the last 10 years than any time during the last 1300 years, and, if the climate scientists include the somewhat controversial data derived from tree-ring records, the warming is anomalous for at least 1700 years.

This is NOT a Hockey Stick

Deniers Obsess about Old Science, Hiding from Corroborative New Research

In a desperate effort to distract attention from the real issue, Steve McIntyre and one of his more loquacious acolytes have renewed their attack on the fabled hockey stick - cheering themselves hoarse over their one, small “victory” in climate science debate, even while the science itself continues to pass them by.

Appended below is a little background on that debate as well as eight other graphs (supported by eight other scholarly papers), all of which independently corroborate Mann's work - and all of which the deniers have ignored with their undivided attention.

Mike Mann and Lee Kump weigh in with "Dire Predictions"

Summer Reading? No, actually, Required Reading

I don't know how I missed Michael Mann and Lee Kump's new book Dire Predictions: Understanding Global Warming in the previous survey of summer reading.

Some of the most prominent deniers in the game have made themselves famous criticizing Michael Mann's work. But here's the deal: Michael Mann DOES the work. He's not a journalist or politician (Christ Monckton); he's not an Philip Morris and Exxon Mobil consultant (Fred Singer); he's not a stock promoter and amateur statistician (Steve McIntyre). He is an Associate Professor in the Department of Meteorology and Geosciences at Pennsylvania State University and the rarest thing in the very public debate about climate change: someone who knows what he's talking about.

Canadian Business Wag Has No Business Talking Science

“An issue as important as global warming should not descend into a shouting match between the faithful and the heretical.”

That was the subhead in the print version of Jack Mintz’s March 17 column in Canadian Business and, up to that point, he was making pretty good sense. But then Mintz took to shouting about the heretical Dr. David Suzuki, a man who continues to infuriate certain segments of Canadian society and, especially, Canadian media by honouring science over the theology of unlimited Alberta oil exploitation.

Stupifying Science Alert: Waiting for the Other Shoe

My new favorite correspondent, Alex Avery, advises that the online Denier Brigade is proudly boasting about this Science journal commentary , which Avery says offers a careful reanalysis of proxy records and “finds the late 20th century is not warmer than AD 1,000.”

Avery neglected to include this riposte from the authors of the original (peer-reviewed) Science article.

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