Remember the “hockey stick?” No, not the kind used in the National Hockey League. This hockey stick is a curve first proposed by Michael Mann. Those of a certain age may ask, “What does the Executive Producer of Miami Vice and Crime Story have to do with, well, anything related to this blog?
Not that Michael Mann. This one is “Presidential Distinguished Professor and Director of Penn Center for Science, Sustainability and the Media” at the University of Pennsylvania. Back when climate change was still called “global warming” Prof. Mann developed the infamous model that predicted a rise in global temperatures that would accelerate, leading to the extinction of all life (or something close to that). Here is his main finding (as summarized by Mr. Burge) and the first known appearance of a hockey stick in climatology. (The link in the text did not work so I removed it.)
The approach of Mann et al. resulted in temperature reconstructions that looked markedly different from the one previously estimated, and first receive widespread notice in a 1998 Mann paper that appeared in Nature. The new reconstruction estimated a relatively flat historical temperature series until the past hundred years, at which point it began rising dramatically, and accelerating around 1990. This is the celebrated “hockey stick” with which we are all familiar.
Fig01 Mann’s Hockey Stick (click for larger image)
The astute observer will have noticed that the horizontal axis has the world ending in about 1995-2000. As far as I know, I’m still here. As are most (hopefully all) of you. Isn’t it fun to look at failed predictions 26 years after the fact?
Luckily, David Burge (iowahawk, on X as @iowahawkblog) worked with Stephen McIntyre to develop an Excel model that lets you grow your own hockey stick. Those unfamiliar with principle components analysis and other statistical methods should probably not try this.
