Carbon dioxide is a greenhouse gas produced by natural processes and everyday human activities, especially the burning of fossil fuels. The numbers here are from measurement of the concentration of carbon dioxide in the atmosphere made daily atop Hawaii’s Mount Mauna Loa. Records, kept since 1958, show a steady increase in atmospheric CO2.
Carbon dioxide concentration in the atmosphere is measured in parts per million -- ppm
Sept. 14, 2019 -- 408.12 ppm
Sept. 14, 2018 -- 405.40 ppm
Go to scripps.ucsd.edu for more detailed information.