Smithsonian: For the first time in human history, later this month the world`s atmospheric levels of carbon dioxide will likely exceed 400 parts per million, according to a study conducted by the Scripps Institution of Oceanography. The researchers monitor CO2 concentrations from a station in Hawaii, and those levels usually peak in May. Right now, levels are teetering at 399 ppm. If they do not exceed 400 ppm this year, the researchers say, they almost certainly will next year.
In March 1958, when the first...