Since the first Earth Day, CO2 levels on the planet have spiraled out of control

Average levels of carbon dioxide in Earth's atmosphere more than 417 ppm in 2022(opens in a new tab)and even recently reached a daily value of more than 424 ppm(opens in a new tab). When this story was first published in 2019, CO2 levels were around 412 ppm. They rise relentlessly. When Americans celebrated the first Earth Day on April 22, 1970, the planet's atmosphere was vastly different from today's. Fifty years ago, scientists measured(opens in a new tab) The level of carbon dioxide—the planet's most important greenhouse gas—on Earth is about 325 parts per million, or ppm. Now, five decades later, that number has shot up to about 412 ppm, an increase of almost 90 ppm. It's a change that atmospheric researchers, geologists and climatologists call unparalleled in at least 800,000 years, although carbon dioxide levels likely haven't been this high in millions of years. "The rate of CO2 increase since the first Earth Day is unprecedented in the geologic record," said Dan Breecker, a paleoclimatologist at the University of Texas at Austin. "Without any way you look at it, it's completely unprecedented," agreed Kris Karnauskas, an associate professor in the Department of Atmospheric and Oceanic Sciences at the University of Colorado Boulder. (Mark Kaufman)