Atmospheric CO2: 750,000 years ago to the present (ppm). Changes in past atmospheric carbon dioxide concentrations as determined by measuring the composition of air trapped in ice cores from Antarctica (and recent direct atmospheric measurements). DATASOURCES: World Data Center for Paleoclimatology and NOAA. WIDGET: factgraphs.org
If conservatives believe that “the precautionary principle” is worth embracing in non-environmental contexts, why don’t they believe that it is worth embracing in the environmental arena? The warming scenarios at one extreme of the distribution of possible outcomes, after all, might well render the planet uninhabitable.