Time rate of atmospheric 3He/4He change: An attempt to measure anthropogenic CO2 flux

Taking into account recently published data, the author assesses possible time rate change of atmospheric 3He/4He ratio. Three independent estimations are considered and the common value of the 3He/4He variations is proposed. The most reliable decreasing rate of atmospheric 3He/4He ratio, 0.032 ± 0.013 %/year is consistent with the anthropogenic emission of crustal helium of 3.1x1011 mol/year estimated by the statistics of global fossil fuel exploitation and the probable carbon/helium ratio in the fuel. Because of the inert chemistry of helium, atmospheric 3He/4He change may provide a marker against which to calibrate the absolute flux and retention of anthropogenic CO2 in the atmosphere.