Alarmists like to rattle off “hottest years ever” lists, which inevitably make it sound like the last few years are the scorchiest scorchers the planet has ever seen. One of the problems with those stories, though, is that “ever” is usually a very short time. Calling 2017 the hottest year “ever” when your record only goes back a few decades is hardly meaningful. Or even fair. So it’s nice to get records long enough to have a chance at capturing real climate complexities and fluctuations. One recent study used Mediterranean tree rings to reconstruct summertime temperatures back to the early 700s. The hottest year ever for that region? 1648. Also on the list were 1845, 1797, 1710, 919, 876, 817, 808 and, in case you thought recent times were left out, 2007. But the hottest 30-year stretch was way back in AD 876-905. And yes, there is a warming trend in the record, but it begins about 900 years ago. In this thing called the Medieval Warm Period. Dang.
Another interesting, even disquieting, feature of the temperature reconstruction is that after the record-setting warm spell in the 800s that saw the happy reigns of Alfred the Great and Edward the Elder in England and Charlemagne in the Kingdom of the Franks/Roman Empire (Mark II), the 900s plunged quickly to reach the coldest era in the whole record, undercutting all these claims we keep hearing about how we’re now seeing faster rates of climate change than ever before, that climate used to be stable and so on. (And bringing turmoil and misery to England and France that indicate once more that warming is not an unmitigated disaster nor cold an unmixed blessing.) And the authors noted that other studies have found evidence of a similar plunge a short while later in the Swiss Alps.
Since this warming and cooling obviously had to be due to natural causes, they might just indicate that climate can swing naturally by more than alarmists often claim. And worse for climate orthodoxy, it shows that the climate models we’re meant to rely on to predict the shadowy future aren’t much help explaining the unknown past.
The authors looked at the simulations from several top models for the same long interval, and found that not only did they not agree with the temperature reconstructions, they didn’t even agree with each other. Other than that, the science is settled.
The mercury thermometer was invented in 1714, and took until about 1800 to establish repeatability in manufacture and calibration although the Hudson Bay company sent some to fur trapper outposts circa 1780’s. Proxies before 1800 are based on assuming the chosen proxies match 1800 and later temperatures. This assumption has a real risk of being complete nonsense, and that the “unprecedented” rates of change we see today may be completely normal, just previously unmeasured.