* Data from 2009 found that the global mean  concentration was rising at a rate of approximately 2 ppm/year and accelerating.
* The daily average concentration of atmospheric  at Mauna Loa Observatory first exceeded 400 ppm on 10 May 2013 although this concentration had already been reached in the Arctic in June 2012. Data from 2013 showed that the concentration of carbon dioxide in the atmosphere is this high "for the first time in 55 years of measurement—and probably more than 3 million years of Earth history."
* As of 2018,  concentrations were measured to be 410 ppm.