Other people’s emails

I agree with McArdle who agrees with Cowen and Hanson. There appears to be consensus in the literature…

Lesson one: scientists are people, people are jerks and that Mann guys seems to be an especially big person.

Lesson two: its way too fun reading other people’s email.

Lesson three (the real lesson): data and methods should be freely available. Reading all the nonsense that goes on trying to replicate policy-important studies (like the Mann et al 1999 paper) is infuriating. Luckily, in my experience, we don’t have this problem in economics.

Contrary to McArdle and Cowen, my prior on the joint claim “the last century was the hottest of the millennium” or “tree ring data is a good proxy for temperature” has decreased reading some of the replication studies. While thermometer readings show a pronounced increase in temperatures in recent decades, the tree ring data probably doesn’t. There’s even a good chance the tree ring data, if a good temperature proxy, show several periods in the past 1000 years that were warmer than the last century.

Here’s a paper in Science that uses a different data set from Mann paper and shows the so-called “Medieval Warm Period” probably had temperatures at least as high as the 20th century.

I haven’t seen a good explanation for why thermometer readings show different trends than tree rings (or other temperature proxies). Of course, I trust thermometers over proxies, but still.

5 thoughts on “Other people’s emails”

  1. I agree with James Inhofe — that an email which catch a global scientist calling global warming skeptics “idiots” means that global warming is a hoax.

  2. This reminds me of something I used to teach new hires at my company: assume all email, all chat sessions, and all SMSes are archived forever. Assume all phone conversations are recorded. Assume anything you ever communicate through an electronic medium can be recalled at any time by opponents, and be careful to phrase things in such a way that they can be defended later.

    By how much do thermometer trends differ from tree ring trends? Tree ring data seems limited to annual trends at best; how granular can you really get before the, uh, resolution drops off?

  3. Tree rings would suggest cooling in the couple of decades before 1990.

    Doug, !(statement of typical politicians) = TRUE

  4. When many proxies are combined to synthesize a temperature record, how far off are they from the instrumental record? Tree rings aren’t the only proxy used.

    I think this paper is the rebuttal to the McIntyre/McKitrick paper you linked above.

  5. Yeah, it may be a language barrier (McKitrick is an economist), but I’m not able to parse that rebuttal, or any of the rebuttals I’ve seen, as well as the MM paper. Also, I’d like to see papers written by people who are that Mann dude and/or his co-authors.

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