Daily Average Mauna Loa CO2:
Week beginning on March 28, 2021: 418.03 ppm Weekly value from 1year ago: 415.95ppm Weekly value from 10years ago: 393. 88ppm Last updated: April 5, 2021
Source: National Oceanic and Atmospheric Administration; Mauna Loa Observatory has been monitoring C02 levels since 1958