When and where was CO₂ first measured?

The first continuous measurements of CO₂ in the atmosphere began in March 1958 at the Mauna Loa Observatory in Hawaii [gml.noaa.gov]. This pioneering project was led by scientist Dr. Charles David Keeling, and it marked the start of the famous “Keeling Curve” record of rising CO₂. Back in 1958, CO₂ was about 313–315 ppm [gml.noaa.govplotnick.medium.com]. For context, that has since climbed to over 420 ppm today. Mauna Loa was chosen because it’s high up (on a volcano) in the middle of the Pacific, far from cities – an ideal spot to measure “background” atmospheric CO₂. These measurements (continued by NOAA and Scripps Institution of Oceanography) have given us an invaluable long-term record of how CO₂ has increased over the decades [gml.noaa.gov].