NOAA/WDS Paleoclimatology - Paleo-pCO2 Database Inner Mongolia Early Miocene Stomata CO2 Data

Eocene paleoclimate reconstructions are rarely accompanied
by parallel estimates of CO2 from the same locality, complicating
assessment of the equilibrium climate response to elevated CO2. We
reconstruct temperature, precipitation, and CO2 from latest middle
Eocene (ca. 38 Ma) terrestrial sediments in the posteruptive sediment
fill of the Giraffe kimberlite in subarctic Canada. Mutual climatic
range and oxygen isotope analyses of botanical fossils reveal a humidtemperate
forest ecosystem with mean annual temperatures (MATs)
more than 17 °C warmer than present and mean annual precipitation
~4× present. Metasequoia stomatal indices and gas-exchange modeling
produce median CO2 concentrations of ~630 and ~430 ppm, respectively,
with a combined median estimate of ~490 ppm. Reconstructed
MATs are more than 6 °C warmer than those produced by Eocene
climate models forced at 560 ppm CO2. Estimates of regional climate
sensitivity, expressed as ?MAT per CO2 doubling above preindustrial
levels, converge on a value of ~13 °C, underscoring the capacity for
exceptional polar amplification of warming and hydrological intensification
under modest CO2 concentrations once both fast and slow
feedbacks become expressed.