5 Carbon dioxide (CO2)

5 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 chart on the left shows the CO2 levels in the Earth's atmosphere during the last three glacial cycles, as reconstructed from ice cores. The chart on the right shows CO2 levels in recent years, corrected for average seasonal cycles.

4The time series at right shows global distribution and variation of the concentration of mid-tropospheric carbon dioxide in parts per million by volume (ppmv) at an altitude range of 3-13 kilometers (1.9 to 8 miles).