For the second year in a row, carbon dioxide levels in the atmosphere have increased at a record rate, jumping 3 parts per million (ppm) in 2016, according to data from the National Oceanic and Atmospheric Administration. CO2 concentrations rose 3.03 ppm in 2015, making the last two years the first time that the greenhouse gas has risen more than 3 ppm in NOAA’s 59 years of monitoring, Climate Central reported.