Earth and Planetary Science Letters Has an interesting paper in the works. A new proxy informs a model which finds bigger than expected swings in CO2 linked to smaller than expected temperature swings in the past five million years. This indicates that the Earth’s climate system is less sensitive to CO2 levels than previously thought. Maybe they should take more notice of Leaf Stomata calibrations than Antarctic ice cores?
CO2 over the past 5 million years: Continuous simulation and new δ11B-based proxy data
During the past five million yrs, benthic δ18O records indicate a large range of climates, from warmer than today during the Pliocene Warm Period to considerably colder during glacials. Antarctic ice cores have revealed Pleistocene glacial–interglacial CO2 variability of 60–100 ppm, while sea level fluctuations of typically 125 m are documented by proxy data. However, in the pre-ice core period, CO2 and sea level proxy data are scarce and there is disagreement between different proxies and different records of the same proxy. This hampers comprehensive understanding of the long-term relations between CO2, sea level and climate.