Global atmospheric concentration of carbon dioxide 1990-2024, by month
Monthly mean atmospheric carbon dioxide concentrations reached a record high of 425.4 parts per million (ppm) in March 2024. This was an increase of roughly 15 percent compared with average levels recorded in February 2000. In 2023, global average annual CO₂ concentrations reached a record high of 421 ppm.
CO₂ concentrations typically fall during the summer months. This is a result of plants taking in more CO₂ through photosynthesis than they release through respiration during the warmer months when they are growing the most.