The Hockey Stick

McIntyre and McKitrick have obtained a lot of attention for their attack on the hockey stick graph of Mann, Bradley, and Hughes, which shows the average climate over the past millennia. (In fact, it shows a rapid rise between 1900 and 2000 after 900 years of relative stability.)

As you’ll recall, M&M made a big stink out of their inability to replicate MBH’s results, publishing in Geophysical Research Letters, which led to a major writeup in the Wall Street Journal. Neither McIntyre or McKitrick is a climatologist, and their results have always been in somewhat of a limbo.

Now Caspar Ammann, a paleoclimatologist at the National Center for Atmospheric Research (NCAR) and Eugene Wahl of Alfred University have analyzed the Mann-Bradley-Hughes (MBH) climate field reconstruction and reproduced the MBH results using their own computer code.

In fact, they found the MBH method is robust even when numerous modifications are employed. Their findings “contradict the assertion by McIntyre and McKitrick that 15th century global temperatures rival those of the late 20th century and therefore make the hockey stick-shaped graph inaccurate.”

They also dispute McIntyre and McKitrick’s alleged identification of a fundamental flaw that would significantly bias the MBH climate reconstruction toward a hockey stick shape. Ammann and Wahl
conclude that the highly publicized criticisms of the MBH graph are
unfounded.”

As climatologists their work deserves a lot of credit, and hopefully it can begin to end the controversy MBH have found themselves in over the last year and a half.