CO2 Crash: Atmospheric CO2 down Sunday to 399.54 ppm from Friday high of 399.88 ppm Friday was a new high. Read more at Keeling_Curve’s Twitter feed. Share this: Click to email a link to a friend (Opens in new window) Email Click to print (Opens in new window) Print Click to share on X (Opens in new window) X Click to share on Facebook (Opens in new window) Facebook More Click to share on LinkedIn (Opens in new window) LinkedIn Click to share on Pinterest (Opens in new window) Pinterest Click to share on Tumblr (Opens in new window) Tumblr Click to share on Reddit (Opens in new window) Reddit