CO2 concentrations ranged between 180 ppm to 220 ppm from about 15 to 60 thousand years ago. Several new temperature reconstructions indicate there were millennial-scale periods with multiple degrees Celsius greater warmth than today (410 ppm CO2) during this glacial period.
Image Source: Ganyushkin et al., 2018
Between 45 and 30 thousand years ago, or during the middle of the last glacial, atmospheric CO2 levels hovered around 200 ppm – less than half of today’s concentration.
Image Source: Kohfeld and Chase, 2017
Tree remains dated to this period have been discovered 600-1000 meters atop the modern treeline in the Russian Altai mountains. With lapse rate and tectonic changes considered, this suggests surface air temperatures were between 3°C and possibly up to 5.9°C warmer than today (Ganyushkin et al., 2018) at this time.
Image Source: Ganyushkin et al., 2018
Modern sea surface temperatures of 15.5°C and 10°C have been recorded in the subpolar North Atlantic (Tobago Basin and Bonair Basin, respectively). Between and about 10 and 15 thousand years ago, temperatures reached 23°C and 17°C, respectively, which is ~7°C warmer than today). Temperatures were 2-4°C warmer than today between 20 and 30 thousand years ago (Reißig et al., 2019).
Image Source: Reißig et al., 2019
Today’s North Atlantic’s bottom-water temperatures are about 4°C. They averaged ~5°C during the last glacial, with anomalies reaching 10°C both 13 and 16 thousand years ago and about 7°C both 15 and 19 thousand years ago (Yasuhara et al., 2019).
Image Source: Yasuhara et al., 2019
Modern annual temperatures at a California lake average 18°C. Between 31 and 24 thousand years ago, temperatures averaged 22°C to 23°C, which is about 4-5°C warmer than today (Feakins et al., 2019).
Image Source: Feakins et al., 2019
The modern temperature in the subarctic North Pacific ranges beween 3 to 4°C. About 14,500 years ago, the region had warm peaks of 5 to 9°C, as well as 4 to 7°C between 18 and 20 thousand years ago (Lohmann et al., 2019).
Image Source: Lohmann et al., 2019
Sea surface temperatures near the Peruvian coast have plummeted in the last 50 years, with catfish remains in northern Peru suggesting this region was 4°C warmer than today during the Early Holocene. One reconstruction shows the region was ~2°C warmer than today about 15 to 16 thousand years ago (Salvatteci et al., 2019).
Image Source: Salvatteci et al., 2019
The “present observed temperatures” appear to be less than 24°C in the South Atlantic. This region was about 2°C warmer than today from about 10 thousand years ago to the Roman Warm Period, but it also reached similar or slightly (~1°C) warmer temperatures around 52 to 60 thousand years ago (Dauner et al., 2019).
Image Source: Dauner et al., 2019
None of these 7 temperature reconstructions support the contention that rising and falling CO2 concentrations have driven regional climate changes during the last 60 thousand years.
What “science” all too often is, but should NEVER be.
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