Daily Average Mauna Loa CO2:
Week beginning on Nov. 17, 2019: 410.19 ppm Weekly value from 1 year ago: 408.52 ppm Weekly value from 10 years ago: 386.36 ppm Last updated: Nov. 26, 2019 Source: National Oceanic and Atmospheric Administration; Mauna Loa Observatory has been monitoring C02 levels since 1958