compared to CO2 emissions from fossil fuel and cement manufactured is called the "airborne fraction.". The airborne fraction has been around 60% since the 1950s, indicating that about 60% of the new carbon dioxide in the atmosphere each year originated from human sources. For clarity, this is not meant to suggest that 60% of the uptake of carbon dioxide into the atmosphere comes from human activity. It means that the atmosphere exchanges around 210 gigatonnes of carbon annually, but absorbs between 6 and 10 gigatonnes more than it loses. Of this net gain, about 60% is attributable to the burning of fossil fuels. Gallery References External links Advanced Global Atmospheric Gases Experiment Carbon Dioxide - Global Circulation (NASA; 13 December 2016) Carbon Dioxide - Information Analysis Center World Data Centre for Greenhouse Gases Atmospheric chemistry Carbon cycle Climate change and the environment