On February 14, 2023 we announced our Rebuttal Update Project. This included an ask for feedback about the added "At a glance" section in the updated basic rebuttal versions. This weekly blog post series highlights this new section of one of the updated basic rebuttal versions and serves as a "bump" for our ask. This week features "What evidence is there for the hockey stick?". More will follow in the upcoming weeks. Please follow the Further Reading link at the bottom to read the full rebuttal and to join the discussion in the comment thread there.
The Hockey Stick is a historic graph dating back to a paper published in 1999. It showed Northern Hemisphere temperature variations over the near-thousand year period from 1000-1998: the 'blade' of the stick represented the rapid warming of the late 20th Century. It has an iconic status, both in climate science and in the murky world of science-misinformation, where, naturally, it is despised by all and sundry.
Objections to the Hockey Stick are varied but mostly focussed on the stick's long handle and the data that represents. Obviously, during the centuries going back to 1000, reliable temperature measurements are not available. Fortunately for science, things that lived through that long time, such as certain very old trees, record in the rings of their wood an indication of temperatures, year on year. Gardeners and farmers talk about good and bad growing years and it’s the same for natural systems. For example, cold dry periods make for narrow and densely-packed tree-rings whereas warmer, wetter times lead to more widely-spaced ones.
Importantly, today there are a great many such past climate indicators, known as proxies because they act in place of thermometers. Because there's a range of indicators, the results from each one can be cross-checked against one another: if a new proxy is any good, its data should agree with that from the other, established ones
Proxy datasets contain more uncertainty than directly measured temperatures. Everyone knows that. That does not mean they are useless, far from it, because that aforementioned cross-checking means poor data can be readily identified and investigated. Finally, in the 24 years since the Hockey Stick graph was published, work on developing and refining the best proxies has been relentless: better, longer temperature reconstructions have become possible. And of course, global temperatures have continued to climb: in any of the observation-based datasets of surface temperature, all of the eight warmest years on record have occurred since 2015.
Please use this form to provide feedback about this new "at a glance" section. Read a more technical version via the link below!
In case you'd like to explore more of our recently updated rebuttals, here are the links to all of them:
| Myths with link to rebuttal | Short URLs |
| Ice age predicted in the 1970s | sks.to/1970s |
| It hasn't warmed since 1998 | sks.to/1998 |
| Antarctica is gaining ice | sks.to/antarctica |
| CRU emails suggest conspiracy | sks.to/climategate |
| What evidence is there for the hockey stick | sks.to/hockey |
| CO2 lags temperature | sks.to/lag |
| Climate's changed before | sks.to/past |
| It's the sun | sks.to/sun |
| Temperature records are unreliable | sks.to/temp |
| The greenhouse effect and the 2nd law of thermodynamics | sks.to/thermo |
Posted by John Mason on Tuesday, 21 March, 2023
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