Temperature Feedback Follies
2 hours ago Charles Rotter 6 Comments
Is it really the hottest in 125,000 years, and if so, what does that imply?
By Chris Hall
The motivation for this article came from claims that this summer was the hottest in 125,000 years and the breathless fear surrounding this. Just skimming the news reports suggested to me that this was based on two main points: the assumption that climate is very stable and has not varied before recent anthropogenic forcing, and that the present deviation above normal temperature was many standard deviations (sigma) above what is expected that it could not possibly have be matched or exceeded for 125,000 years.
The first assumption aligns with a “Hockey Stick” style paleotemperature reconstruction, where there is tiny natural temperature variability for the last millennium. There are several reconstructions like this, e.g. some of the flatter Temp12k records, along with the classic Hockey Stick (Figs. 1 and 2). The second assumption is based on the faith that the statistical properties of the paleoclimate temperature record have not changed at all for a very protracted time period.
: Figure 1: Classic “Hockey Stick Graph” paleotemperature reconstruction, from its Wikipedia entry.
Figure 2: Collection of paleotemperature reconstructions from Fig. 3 of Kaufman et al., 2020.
Although I will not argue one way or the other on any particular paleotemperature reconstruction, I will point out that the 125,000 years mentioned for our record breaking temperatures comes from a little bit of sleight of hand. If you look at the Vostok ice core temperature record that is on the paleoclimate page of wattsupwiththat (Fig. 3), as soon as you go back about 12,000 years to the beginning of the Holocene, the temperature drops sharply into the depths of a severe glacial period, and you only get back to “normal” after you travel back in time roughly 125,000 years until you get to the toasty Eeemian. So, in reality, it’s not much of an achievement being hotter than the vast canyon of the glacial freeze. Saying that, the question becomes, was 2023 the hottest year, and was August of 2023 the hottest month, in 12,000 years?
https://wattsupwiththat.com/2024/02/13/temperature-feedback-follies/
