Carbon dioxide (CO2) is an important heat-trapping (greenhouse) gas, which is released through human activities such as deforestation and burning fossil fuels, as well as natural processes such as respiration and volcanic eruptions. The first chart shows the CO2 levels in the Earth's atmosphere during the last three glacial cycles, as reconstructed from ice cores. The second chart right shows CO2 levels in recent years, corrected for average seasonal cycles.
The time series below shows global distribution and variation of the concentration of mid-tropospheric carbon dioxide in parts per million (ppm). The overall color of the map shifts toward the red with advancing time due to the annual increase of CO2.