Current concentrations of the minor components in Earth's atmosphere.

Bloom (2010) Global Climate Change: Convergence of Disciplines. Sinauer Associates.

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Rising CO2 Levels: Earth's Changing Atmosphere Last Updated on 2010-12-16 00:00:00 An important impact of climate change is a rise in the level of carbon dioxide and a decline in oxygen levels. Atmospheric concentration of CO2 has risen from about an average of 0.027% (270 ppm) in preindustrial times to 0.039% at present and is anticipated to reach between 0.05% and 0.10% by the end of the century. These concentrations exceed any that have occurred during the last 20 million year. Direct effects of such changes on organisms can be profound. The atmospheric CO2 concentration anticipated during this century is only a small fraction of the concentrations that cause respiratory distress. Human beings suffer loss of mental acuity at a CO2 concentration between 2% and 7.5%, loss of consciousness at between 5% and 10%, and loss of life at between 20% and 30%. The National Research Council recommends that long-term exposure to CO2 in submarines be kept below 0.8%... More »