California’s Mean Annual Temps Were Up To 3.8°C Warmer Than Today During The Last Glacial

From NoTricksZone

By Kenneth Richard on 15. May 2023

From 14,000 to 45,000 years ago, when the atmospheric CO2 values were said to be under 200 ppm, California lakes record millennial-scale mean annual air temperature (MAAT) variations of over 12°C and intervals when it was nearly 4°C warmer than modern.

Per a new paleotemperature reconstruction (Olson et al., 2023) from a California lake, there were periods during the last glacial when MAATs were both significantly colder (11.8°C) and warmer (23.9°C) than today (20.1°C).

The Holocene, ~250-275 ppm CO2, has also had periods when paleotemperatures were multiple degrees warmer than modern.

Image Source: Olson et al., 2023

Another California paleotemperature reconstruction (Feakins et al., 2019) also indicates the last glacial had abrupt warm-up periods reaching 10-15°C and MAATs ranging up to 4 to 5°C warmer than today (18°C vs. 22-23°C) between 31,000 and 24,000 years ago.

Image Source: Feakins et al., 2019

These temperature reconstructions do not support the contention that atmospheric CO2 concentrations are a driver of climate variations.