(John A): On Jerry Pournelle’s fascinating weblog, a poster has mentioned Steve McIntyre’s expanded horizons into the world of multiproxy studies and the revealing reply to the NAS Panel by D’Arrigo in praise of cherrypicking proxies because "that’s what you have to do if you want to make cherry pie".
The basis assumption of statistical inference is random selection of the sample. If that assumpti0n is not met, other inferential tools are required.
Am I correct in concluding that the Hockey Stick has rather quietly vanished as its assumptions were exposed?
Do understand that exposing the alarmists as having systematically selected data is not the same as proving they are wrong; it does mean they have not accounted for all the data.
Later he adds:
Pity it’s not science yet. I would think it important to turn real science loose on a problem of this importance.
It’s been more than a year since the last post on the climate science version of "Where’s Wally?". The Hockey Stick has hardly vanished. A commenter noticed that NOAA persists in presenting the Hockey Stick as fact:
In the early days of paleoclimatology, the sparsely distributed paleoenvironmental records were interpreted to indicate that there was a "Medieval Warm Period" where temperatures were warmer than today. This "Medieval Warm Period" or "Medieval Optimum," was generally believed to extend from the 9th to 13th centuries, prior to the onset of the so-called "Little Ice Age."
In contrast, the evidence for a global (or at least northern hemisphere) "Little Ice Age" from the 15th to 19th centuries as a period when the Earth was generally cooler than in the mid 20th century has more or less stood the test of time as paleoclimatic records have become numerous. The idea of a global or hemispheric "Medieval Warm Period" that was warmer than today however, has turned out to be incorrect.
This is fascinating to me that "the early days of paleoclimatology" were so recent. It makes me feel old that I can remember such ancient times as if they were yesterday.
For example, Mann et al. (1999) generated a 1,000 year Northern Hemisphere temperature reconstruction (shown above) using data from multiple ice cores and tree ring records. This reconstruction suggests that the 1998 annual average temperature was more than two standard deviations warmer than any annual average temperature value since AD 1,000 (shown in yellow).
In summary, it appears that the 20th century, and in particular the late 20th century, is likely the warmest the Earth has seen in at least 1200 years.
Or is it merely "plausible"?