By Kenneth Richard on 10. August 2023
Proxy temperature records calibrated to closely align with current instrumental temperatures undermine the current “global boiling” narrative when extended to the 18th century.
Per a new study, maximum latewood density (MXD) tree-ring data have been observed to strongly correlate (r=0.77) with the modern (1959-2016) maximum (July-Aug.) instrumental temperature record (Li et al., 2023). In other words, MXD series from centuries-old trees can reliably record the warmest temperatures of the year when investigating the correspondence to measured thermometer temperatures.
So it may be surprising to learn that when assessing the 1720-2018 temperatures by extending MXD data over the last 3 centuries, a non-warming (cooling) trend since 1900 emerges in the data from northwestern China, including a ~1°C warmer 1920s-’30s.
The authors point out that these trends (“none of these MXD series showed a warming trend in the last century”) have been observed in several other regions of the world, including eastern Asia, southern Europe, and northwestern Africa.
Both the instrumental (1900-2015) and proxy (1765-2002) temperature records closely agree that the Tierra del Fuego forested region – located at the southernmost tip of South America – has been cooling (net) since 1900 (instrumentals and proxies) and 1765 (proxies), respectively (Matskovsky et al., 2023).
Image Source: Matskovsky et al., 2023
In 2007 the IPCC relied upon a WWF claim that said, due to warming, the Himalayan glaciers would very likely melt or “disappear” by 2035 (or sooner).
But a new study reconstructing 1733-2020 Nepal-Himalaya temperatures indicates there has been no net warming here in 288 years.
Another new study indicates the southeastern Tibetan Plateau was as-warm or warmer than recent decades in the 1870s and 1930s-’40s. Also, the warming and cooling oscillations over the last few hundred years correlate well with the naturally-varying AMO.
Finally, a 1733-2010 minimum temperature reconstruction for south-central China reveals an oscillating trajectory, with no net warming throughout the nearly three centuries (Li et al., 2023). A recent warming trend is evident in the data, but only if the record begins in 1960, a particularly cold period of years.