Atmospheric carbon dioxide rises at fastest rate on record in 2024

Atmospheric carbon dioxide levels soared by a record amount in 2024, the United Nations reported Wednesday, highlighting the urgent need for global action to cut greenhouse gas emissions.

According to the World Meteorological Organization (WMO), the concentrations of the three main long-lived greenhouse gases — carbon dioxide, methane, and nitrous oxide — all reached unprecedented highs last year. CO2 climbed to 424 parts per million (ppm), marking the largest single-year increase since systematic measurements began in 1957. Methane rose to 1,942 parts per billion, and nitrous oxide reached 338 parts per billion, representing rises of 266 percent and 125 percent above pre-industrial levels, respectively.

“The heat trapped by CO2 and other greenhouse gases is turbocharging our climate and leading to more extreme weather,” said WMO Deputy Secretary-General Ko Barrett. “Reducing emissions is therefore critical for climate stability, economic security, and community well-being.”

The report comes ahead of the COP30 UN climate summit in Belem, Brazil, scheduled for November 10-21. While this bulletin focuses on atmospheric concentrations, a separate UN report next month will track global emissions trends, which are also expected to rise as fossil fuel consumption continues.

The increases in greenhouse gases defy the targets of the 2015 Paris Agreement, which aims to limit global warming to well below 2°C — or 1.5°C if possible — compared with pre-industrial levels. WMO warned that both land and oceans are increasingly unable to absorb excess CO2, leaving more of the gas in the atmosphere.

2024 was also the warmest year on record, surpassing 2023. CO2 remains the most significant contributor to global warming, accounting for roughly two-thirds of the effect. Since the first WMO Greenhouse Gas Bulletin in 2004, CO2 concentrations have risen from 377 ppm to 424 ppm, with the 3.5 ppm increase from 2023 to 2024 marking the largest annual jump ever recorded.