Global atmospheric carbon dioxide concentration 1959-2023

Average annual atmospheric levels of carbon dioxide (CO₂) reached a record high of 421.08 parts per million (ppm) in 2023. Monthly atmospheric CO₂ concentrations peaked that year in May, at 424 ppm. 

Human activities have caused CO₂ concentrations to soar

Annual CO₂ concentrations consistently averaged around 280 ppm before the industrial revolution began, according to the National Oceanic and Atmospheric Administration (NOAA). However, the mass burning of fossil fuels and deforestation over the past two centuries has released trillions of tons of CO₂ into the atmosphere. This has caused atmospheric CO₂ levels to climb more than 50 percent above pre-industrial levels.

Impacts of high atmospheric greenhouse gas levels

The rapidly rising concentrations of greenhouse gases (GHGs) are worrying news for the planet, as they contribute to the climate crisis. GHGs like CO₂, methane, and nitrous oxide trap heat radiating from the planet’s surface, preventing it from escaping into space. This causes Earth’s atmosphere to heat and increases sea surface temperatures. Higher surface temperatures can unleash severe weather conditions such as extreme heat, droughts, and a higher frequency of high-intensity tropical storms.