New IPCC report resurrects the Hockey Stick

by Clintel,  26 Aug 2021

Every IPCC report is accompanied by this kind of ritual dance. The IPCC itself declares in somewhat woolly language (because the IPCC is officially policy neutral) that it is 2 minutes to 12 after which activists, politicians and the media go wild and declare that it is already 2 minutes past 12. This time it was no different.

Now that the media hype around the report has subsided somewhat, it is time to take a calm look at some of the claims in the new IPCC report and also at what the IPCC leaves unsaid or gives less attention to in its Summary for Policy Makers (SPM). I made a first attempt last week in an interview in the popular Studio BLCKBX: “Alarmist IPCC report offers hope” (in Dutch but with English subtitles).

Hockey stick
Back to the opening words in our national news program: “climate change is accelerating”. Most people will let these words pass almost without thinking and will assume “it must be true”. For insiders like me, however, this new conclusion in the IPCC report was downright surprising! The claim is based on a brand new hockey stick graph (the graph at the very top of this article). This graph was the opening graph in the Summary for Policy Makers. So it is a piece of evidence that the IPCC wanted to give a lot of attention. Coupled with yet another graph – with which the IPCC claims to ‘prove’ that the warming since 1850 is mainly due to greenhouse gases – the message was the following: “due to human influence (read: CO2 and other greenhouse gases), the earth has warmed at a rate unprecedented in the last 2000 years”.

Without exaggeration, I would not be writing this article now if, way back in 2004, when I worked at the popular science monthly Natuurwetenschap & Techniek, I had not been asked by my chief editor to write an article about “a hockey stick graph”. It became the beginning of a two-month quest that ended with a long article (English version here) in which the hockey stick graph in the third IPCC report in 2001 was smashed to smithereens by two Canadian researchers (Stephen McInytre and Ross McKitrick). This experience and especially the reactions to it from the field (the unwillingness to acknowledge the criticism of McIntyre and McKitrick) triggered me to start investigating more climate claims, which eventually led to the publication of my book (in Dutch) De Staat van het Klimaat.

The controversy surrounding the hockey stick, especially to be found on Stephen McIntyre’s blog was a central theme in the climate debate for years. It was ultimately also the cause of climategate, an affair in which thousands of e-mails from prominent IPCC authors were hacked and put online. The emails were examined by various committees of enquiry but were ultimately dismissed as a storm in a teacup. But in my book, I show that several emails do shed a very questionable light on the integrity of the IPCC authors involved.

In any case, there is even a hefty book on this matter written by Andrew Montford and it would be going too far to go into it all again. After climategate, all those closely involved became fed up with the subject. And in the fourth (2007) and fifth (2013) IPCC reports, the IPCC did not publish a prominent hockey stick either. But lo and behold, in the sixth IPCC report the hockey stick is back in all its glory. Or as McInytre puts it: “the IPCC is addicted to hockey sticks”.

Where does this attraction to the hockey stick come from? A long time ago, in 1995, a climate researcher once wrote: we have to get rid of the Medieval Warm Period. There is much historical evidence that around the year 1000 it was also warm on Earth. The Vikings went to Greenland, called it Greenland (and not e.g. Iceland), farmed there and managed to survive for several centuries. This kind of information is unwelcome (for the IPCC) because this warm period suggests that even without CO2 emissions it was warm on Earth in the recent past. How warm exactly? Warmer than now? And if so, what caused the warming? There is no simple answer to these questions, but with the introduction of hockey sticks the IPCC suggests there is. Take a closer look.