Atmospheric CO2 (IMAGE) University of Utah Caption This graphic indicates Earth’s atmospheric concentrations of CO2, expressed in parts per million (ppm), throughout the Cenozoic era from pre-industrial times back 65 million years. These are estimates based on proxies encoded in the geological record. The color-coded bars represent global temperature reconstructed from independent proxy data. The dashed line represents where CO2 concentrations stand today at 420 ppm. Credit: Gabe Bowen, University of Utah. Credit Gabe Bowen, University of Utah Usage Restrictions For use in news article only License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.