Carbon Dioxide in Earth's Atmosphere - Current Concentration

Current Concentration

In 2009, the CO₂ global average concentration in Earth's atmosphere was about 0.0387%, or 387 parts per million. There is an annual fluctuation of about 3–9 ppmv which roughly follows the Northern Hemisphere's growing season. The Northern Hemisphere dominates the annual cycle of CO₂ concentration because it has much greater land area and plant biomass than the Southern Hemisphere. Concentrations peak in May as the Northern Hemisphere spring greenup begins and reach a minimum in October when the quantity of biomass undergoing photosynthesis is greatest.