A new profile of Michael Mann appears in the March edition of Scientific American (on the grounds that you can never have too many profiles) Update: the author of the profile is David Appell. Isn’t it a small world? You’ll have to pay real money to see all of it, but here’s a rather revealing extract (my emphasis added):
To construct the hockey-stick plot, Mann, Raymond S. Bradley of the University of Massachusetts Amherst and Malcolm K. Hughes of the University of Arizona analyzed paleoclimatic data sets such as those from tree rings, ice cores and coral, joining historical data with thermometer readings from the recent past. In 1998 they obtained a "reconstruction" of Northern Hemisphere temperatures going back 600 years; by the next year they had extended their analysis to the past 1,000 years. In 2003 Mann and Philip D. Jones of the University of East Anglia in England used a different method to extend results back 2,000 years.
In each case, the outcome was clear: global mean temperature began to rise dramatically in the early 20th century. That rise coincided with the unprecedented release of carbon dioxide and other heat-trapping gases into the earth’s atmosphere, leading to the conclusion that industrial activity was boosting the world’s mean temperature. Other researchers subsequently confirmed the plot.
So yet again, Sci-Am have confirmed what many skeptics have claimed: that the Mann Hockey Stick is indeed the key reconstruction used to "prove" the Greenhouse Warming hypothesis, that the 20th Century warming period is caused by human industrial activity since the dramatic rise in global mean temperature began in the early 20th Century.
In contradiction to the recent statements on realclimate.org and elsewhere, MBH99 is the one reconstruction that everybody reaches for when discussions of "greenhouse warming" and "anthropogenic climate change" are given. That’s why MBH99 is so important.
And yet, no other reconstruction has the warming begin in the mid 19th Century. The latest one by Moburg et al (2005) has the lowest temperature in the mid 17th Century, co-inciding with the depths of the "Little Ice Age" and (obviously by coincidence) the "Maunder Minimum", a period of 70 years when the solar cycle disappeared and the Sun produced about 0.15% less energy than it does today.
Just in case you don’t believe how pivotal the MBH99 paper was in the eyes of the IPCC, here is how the IPCC reconstructed the past 1000 years of climate back in 1990:
As far as I am aware, the IPCC has never bothered to explain why it threw away its previously stated view on climate history and embraced the Hockey Stick so enthusiastically and completely.
But I think I can guess…