High CO2 levels in the Proterozoic atmosphere estimated from analyses of individual microfossils

@article{Kaufman2003HighCL,
  title={High CO2 levels in the Proterozoic atmosphere estimated from analyses of individual microfossils},
  author={Alan J Kaufman and Shuhai Xiao},
  journal={Nature},
  year={2003},
  volume={425},
  pages={279-282}
}
Solar luminosity on the early Earth was significantly lower than today. Therefore, solar luminosity models suggest that, in the atmosphere of the early Earth, the concentration of greenhouse gases such as carbon dioxide and methane must have been much higher. However, empirical estimates of Proterozoic levels of atmospheric carbon dioxide concentrations have not hitherto been available. Here we present ion microprobe analyses of the carbon isotopes in individual organic-walled microfossils… 

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