Global warming deniers are making another attempt at discrediting the famed “hockey stick” graph, based on a paper (McShane and Wyner 2010) that purports to show mistakes in its statistical methods. While I don’t have the statistical chops to assess the validity of either party’s math, I did want to make two observations.
First, as others have noted, even if you assume that the new paper is the “correct” version, it doesn’t look much different from other hockey stick graphs – if anything, the hockey stick shape in the new study is more pronounced.
More importantly, the hockey stick graph ultimately matters very little for what we should do about CO2, since it only measures past temperatures up to around the year 2000. What we really care about isn’t the past temperature increase we’ve already observed, but rather the much larger future increase that’s still to come assuming we do nothing about CO2. And that isn’t accounted for in any existing hockey stick graph. I’ve taken the liberty of (unscientifically) adding this onto the McShane and Wyner hockey stick graph, using a simple average of the IPCC’s low-end (1.1 degrees C) and high-end estimates (6.4 degrees C) for 21st century temperature increase:
Looks more like a hockey skate! Despite deniers’ strange obsession with the past and lack of concern for the future (perhaps by virtue of their conservatism), the bottom line is this: the reliability of past temperature reconstructions matter very little compared to what we have in store… and it’s about to get a whole lot hotter.
If this looks familiar, here’s why: