Global atmospheric concentration of carbon dioxide 1990-2024, by month
Monthly mean atmospheric carbon dioxide (CO₂) concentrations reached a record high of 427 parts per million (ppm) in April 2024. This represents an increase of roughly 20 percent compared with average CO₂ levels recorded in April 1990. 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.