Carbon dioxide content of the atmosphere on April 5, as measured at Mauna Loa Observatory in Hawaii, was 406.45 parts per million (ppm). The same day in 2015 recorded a level of 403.64 ppm. The average level for March 2016 was 403.64 ppm. Level for March 2015 was three points lower.
February 2016 was the warmest world-wide since 1880.
Highest-ever daily CO2 at Mauna Loa was 407.12 recorded on this past March 18. Second-highest level came on March 28.
Daily average value for carbon dioxide in the atmosphere are posted at www.co2.earth as a year-over-year comparison. Measurements are made by the Scripps Institution of Oceanography and the National Oceanography and Atmospheric Administration at the Mauna Loa Observatory in Hawaii, about 11,000 feet above sea level.