Carbon dioxide levels breach another threshold at Mauna Loa

Carbon dioxide levels are tracked closely by the world’s scientists as a measure of how human activity is changing the planet’s atmosphere. The concentration of CO₂  in the atmosphere increases every year, and the rate of increase is accelerating. While it averaged about 1.6 ppm per year in the 1980s and 1.5 ppm per year in the 1990s, the growth rate increased to 2.2 ppm per year during the last decade.

"CO₂ levels are continuing to grow at an all-time record rate because burning of coal, oil, and natural gas have also been at record high levels,” said Pieter Tans, lead scientist of NOAA's Global Greenhouse Gas Reference Network. "Today's emissions will still be trapping heat in the atmosphere thousands of years from now."

Independent measurements of CO₂ at Mauna Loa are made by scientists with NOAA’s Earth System Research Laboratory and Scripps Institution of Oceanography at UC San Diego offsite link. Air samples are also shipped to NOAA’s Earth System Research Laboratory in Boulder, Colorado for verification, as well as further analysis.

The greenhouse effect explained

Carbon dioxide is one of several gases that are primarily responsible for trapping heat in the atmosphere. This “greenhouse effect” maintains temperatures suitable for life on Earth. During the past 150 years, large emissions of CO₂ from human activity have trapped additional heat in the atmosphere and the oceans, making it the main contributor to rising global average temperatures.

Atmospheric CO₂ averaged about 280 ppm between about 10,000 years ago and the start of the Industrial Revolution around 1750. In March 2018, the latest month for which global samples had been analyzed, the global average had climbed to 408.75 ppm.

Visit NOAA's Earth System Research Laboratory to learn more about trends in atmospheric carbon dioxide.