Monday, October 26, 2009

Statisticians reject global cooling

On slow news days, reporters go trolling for man bites dog stories. The AP decided to try statisticians bite denialists and scurried up a few statisticians, showed them the data and asked, hey guys, we got global cooling here. Actually, they were smarter, they just showed the unlabeled numbers and asked, is there a trend? John Grego at South Carolina remarked

"If you look at the data and sort of cherry-pick a micro-trend within a bigger trend, that technique is particularly suspect,"

David Peterson a smarter emeriti from Duke pointed out that

Saying there's a downward trend since 1998 is not scientifically legitimate,

Identifying a downward trend is a case of "people coming at the data with preconceived notions," said Peterson, author of the book "Why Did They Do That? An Introduction to Forensic Decision Analysis."

They shopped quotes from Don "the denialist" Easterbrook

"Should not the actual temperature be higher now than it was in 1998?" Easterbrook asked. "We can play the numbers games."

and let Prof. Grego flatten him

That's the problem, some of the statisticians said.

Grego produced three charts to show how choosing a starting date can alter perceptions. Using the skeptics' satellite data beginning in 1998, there is a "mild downward trend," he said. But doing that is "deceptive."

The trend disappears if the analysis starts in 1997. And it trends upward if you begin in 1999, he said.

Followed by a short drive by on Dubner and Levitt's Superfreakonomics

A line in the book says: "Then there's this little-discussed fact about global warming: While the drumbeat of doom has grown louder over the past several years, the average global temperature during that time has in fact decreased."

That led to a sharp rebuke from the Union of Concerned Scientists, which said the book mischaracterizes climate science with "distorted statistics."

Levitt is trying to roll it back to rescue some respectability, but, of course, the damage is being done both by the book, and it's reception. In this blogs are playing an important role. It is important to a) keep it up and b) realize that this has been effective on at least a personal level with Levitt. He knows that he has a long way to go before people he cares about take him seriously again.

Levitt, a University of Chicago economist, said he does not believe there is a cooling trend. He said the line was just an attempt to note the irony of a cool couple of years at a time of intense discussion of global warming. Levitt said he did not do any statistical analysis of temperatures, but "eyeballed" the numbers and noticed 2005 was hotter than the last couple of years. Levitt said the "cooling" reference in the book title refers more to ideas about trying to cool the Earth artificially.

This should be greeted by a loud chorus.



and Ken Caldeira ain't gonna take it no more
To talk about global cooling at the end of the hottest decade the planet has experienced in many thousands of years is ridiculous," said Ken Caldeira, a climate scientist at the Carnegie Institution at Stanford.
Comments?

10 comments:

Anonymous said...

"Levitt, a University of Chicago economist, said he does not believe there is a cooling trend. He said the line was just an attempt to note the irony of a cool couple of years at a time of intense discussion of global warming."

Molly Ivins' first rule of holes: When you're in one, stop digging.

Ian said...

Like a good economist, Levitt keeps talking about the importance of assessing trade-offs. Apparently he's decided to trade off scientific respectability for fame and $...

carrot eater said...

Dubner and Levitt made several such statements in passing. It's as if they needed some more 'irony', so they found a collection of talking points on a denialist page and then used them without doing any research on them.

While Levitt was eyeballing numbers, did he not bother eyeballing the rest of the history? It'd take just two more seconds to see that warming does not require that every single year be warmer than the preceding one.

Sounds like he was looking at the GISS set, which makes their statement even more puzzling.

Tony Lee said...

Next time I'm running up fast against a hard deadline, I'm sure I can cut corners by "eyeballing". If it's good enough for a world-famous economist...

Anonymous said...

"world-famous economist..."

does not mean much.

in fact, "economist" does not mean much (if anything).

It just means "not good enough in math to get a real science degree."

Anonymous said...

Yeah, when they called it the "dismal science" they were at least half right.

Martin said...

> In this blogs are playing an
> important roll

...when they're on a roll. Perhaps 'role'?

Anonymous said...

MWP-deniers the lot of you.
... of the hottest decade the planet has experienced in many thousands of years...
A complete falsehood.

Notadothead.

Anonymous said...

Not[sic]adothead.

If you are so convinced that the fact to which you refer is a "complete falsehood", you will of course be able to immediately povide a scientifically credible and irrefutable reference that supports your claim.

Not being able to so do in short order will render you an obviously ignorant twit, and will also discredit anything that you have to say on the Interweb.

Bernard J.

Anonymous said...

Levitt, a University of Chicago economist"

From the Chicago "Fruitcake" School of Economics" (founded by Milton Friedman) whose fundamental economic tenet (government regulation is always bad) inspired deregulation of the banks that led to the spectacular meltdown of the world economy.