This is the highest seasonal peak recorded in 61 years of observations

Monthly Average Surpassed 414 Parts Per Million At Mauna Loa Observatory

Atmospheric carbon dioxide continued its rapid rise in 2019, with the average for May peaking at 414.7 parts per million at NOAA’s Mauna Loa Atmospheric Baseline Observatory, scientists from NOAA and Scripps Institution of Oceanography at the University of California San Diego announced today.

This is the highest seasonal peak recorded in 61 years of observations on top of Hawaii’s largest volcano, and the seventh consecutive year of steep global increases in concentrations of carbon dioxide, or CO2. The 2019 peak value was 3.5 parts per million (ppm) higher than the 411.2 ppm peak reached in May 2018; it represents the second-highest annual jump on record. The May monthly average measured by Scripps' instruments was 414.8 ppm, also 3.5 ppm higher than Scripps' May 2018 average.

Monthly CO2 values at Mauna Loa first breached the 400 ppm threshold in 2014.  

Scientists studying how greenhouse gas pollution is changing the planet’s climate and ocean closely track levels of CO2, the most important anthropogenic greenhouse gas.

Charles David Keeling of Scripps initiated on-site CO2 measurements at NOAA’s weather station on Mauna Loa in 1958. NOAA began CO2 measurements there in 1974, and the two research institutions have made complementary, independent measurements ever since. The Mauna Loa data, together with measurements from sampling stations around the world, are made by NOAA’s