FIG. 25.11 Atmospheric CO₂ content for the past 541 million years. Models and indirect estimates from geological measurements suggest that CO₂ levels have varied substantially through Earth’s history. Data from Fig 3.4 in K. Wallmann and G. Aloisi, 2012, “The Global Carbon Cycle: Geological Processes,” in Fundamentals of Geobiology, A. H. Knoll, D. E. Canfield, and K. O. Konhauser (eds.), Chichester, England: Wiley-Blackwell, pp. 20–35.

Data from Fig 3.4 in K. Wallmann and G. Aloisi, 2012, “The Global Carbon Cycle: Geological Processes,” in Fundamentals of Geobiology, A. H. Knoll, D. E. Canfield, and K. O. Konhauser (eds.), Chichester, England: Wiley-Blackwell, pp. 20–35.