Permanent High Levels of Carbon Dioxide in Atmosphere

by Vins
Published: Last Updated on

The planet may have reached a point where the carbon dioxide in the atmosphere will never go below 400 parts per million (or PPM), Brian Kahn reported in September 2016 for Climate Central. The 400ppm level exceeds the figure of 350ppm that most scientists consider “safe” levels of CO2 concentration. The concentration of CO2 in the atmosphere usually dips in September, but this did not happen in 2016. Kahn reported that, according to Ralph Keeling, who runs the Scripps Institute for Oceanography’s carbon dioxide monitoring program, “Brief excursions toward lower values are still possible, but it already seems safe to conclude that we won’t be seeing a monthly value below 400 ppm this year–or ever again for the indefinite future.” As Kahn summarized, “we’re living in a 400 ppm world.” With each passing day, “we’re moving further from the climate humans have known and thrived in and closer to a more unstable future.”

Thom Hartman also covered the news that the concentration of carbon dioxide in the atmosphere has stayed above 400 parts per million throughout the entire year. His report included suggestions for how to “reverse some of the damage we’ve already done,” including leaving fossil fuels “behind once and for all.”


Brian Kahn, “Earth’s CO2 Passes the 400 PPM Threshold—Maybe Permanently,” Climate Central, September 27, 2016,

Thom Hartman, “TitleTime to Save the World Now,” Truthout, October 3, 2016,

Editor’s Note: For more Project Censored coverage on ways to reduce reliance on fossil fuels, see Censored 2017 Story #12, “Why Our Lives Depend on Keeping 80 Percent of Fossil Fuels in the Ground.”

Student Researcher: Tim Pham (Sonoma State University)

Faculty Evaluator: Elaine Wellin (Sonoma State University)