Key points are not available for this paper at this time.
Quantification of the atmospheric concentration of CO2 (CO2atm) during warm periods of Earth's history is important because burning of fossil fuels may produce future CO2atm approaching 1000 parts per million by volume (ppm). The early Eocene (~56 to 49 million years ago) had the highest prolonged global temperatures of the past 65 million years. High Eocene CO2atm is established from sodium carbonate minerals formed in saline lakes and preserved in the Green River Formation, western United States. Coprecipitation of nahcolite (NaHCO3) and halite (NaCl) from surface waters in contact with the atmosphere indicates CO2atm > 1125 ppm (four times preindustrial concentrations), which confirms that high CO2atm coincided with Eocene warmth.
Lowenstein et al. (Thu,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: