Splicing data sets is a virtual necessity in climate research. Let’s think about how I might get a 500,000 year temperature record. For the first 499,000 years I probably would use a proxy such as ice core data to infer a temperature record. From 150-1000 years ago I might switch to tree ring data as a proxy. From 30-150 years ago I probably would use the surface temperature record. And over the last 30 years I might switch to the satellite temperature measurement record. That’s four data sets, with three splices.
Why is that important?
A number of the more famous recent findings in climate have coincided with splices in data sets. The most famous is in Michael Mann’s hockey stick, where the upward slope at the end of the hockey stick occurs exactly at the point where tree ring proxy data is spliced to instrument temperature measurements. In fact, if looking only at the tree ring data brought to the present, no hockey stick occurs (in fact the opposite occurs in many data sets he uses). The obvious conclusion would have been that the tree ring proxy data might be flawed, and that it was not directly comparable with instrumental temperature records. Instead, Al Gore built a movie around it.
Read the whole thing. Interesting to see how data splices may be causing mayhem in the climate debate.
Speaking of mayhem... Apparently a number of climate change temperature reporting stations are in terrible locations (hot asphalt, etc) and pushing out bad data. Anthony Watts has set up a website that you can use to check the condition of your local site.
Now's your chance to really get involved in climate science, instead of just getting cranky about reluctant politicians.
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