Latest analysis global observations show that concentrations of the three most abundant long-lived greenhouse gases (LLGHGs) – carbon dioxide (WHAT2​), methane (CH4) and nitrous oxide (N2O) – reached unprecedented highs in 2024These The findings confirm the continuing acceleration of the trend driving global climate change.

Carbon Dioxide (CO2): Largest Annual Increase on Record

Carbon dioxide is the dominant LLGHG that has shaped global climate throughout Earth's history and is currently driving global warming.

The globally averaged CO2 concentration at the Earth's surface reached in 2024 423.9 ± 0.2 ppmThis level represents 152 % of the pre-industrial level (278.3 ppm).

The most alarming finding is record annual growthFrom 2023 to 2024, the concentration of CO2 in the global surface atmosphere increased by 3.5 ppmIt is about the largest increase in one year in the modern record of measurements, which began in 1957. This increase significantly surpassed the previous record of 3.3 ppm (from 2015 to 2016) and far exceeded the increase of 2.4 ppm from 2022 to 2023.

Causes of record acceleration

The acceleration in growth rate reflects a combination of two key factors:

1. Continued fossil CO2 emissions (global fossil emissions remained almost static at a record level of 10.2 ± 0.5 GtC/year in 2023-2024).
2. Reduction of absorption flowsGlobal terrestrial ecosystems and oceans are likely responsible for the additional increase in CO2.

Most of the CO2 increase anomaly in 2024 results from reduced net carbon sequestration by ecosystems a increased emissions from fires. Global temperatures in 2024 were the highest recorded since 1850 and exceeded 1.5°C above pre-industrial levels for the first time, partly due to long-term warming and the El Niño event in 2023–2024. El Niño changes regional temperature and precipitation patterns, affecting CO2 absorption and increasing the frequency and intensity of wildfires.

Regions such as the Amazon and southern Africa experienced in 2023-2024 record high fire activity associated with extreme drought. CO2 and carbon monoxide emissions from fires in the Amazon were the highest in 15 years in 2024. There is serious concern that land and ocean CO2 absorption is becoming less efficient, which will accelerate global warming.

Methane (CH4) and Nitrous Oxide (N2O)

Concentrations of methane and nitrous oxide also reached new highs.

Methane (CH4):

• Global concentration reached 1942 ± 2 ppb in 2024, which is 266 % of pre-industrial levels.
• The annual increase was 8 ppb.
• This increase was lower than the 11 ppb increase observed from 2022 to 2023 and lower than the average annual growth rate over the past decade (10.6 ppb yr‐1).
• Approximately 60 % of methane comes from anthropogenic sources, dominated by agriculture and waste, not fossil fuel-related emissions.

Nitrous oxide (N2O):

• Global concentration reached 338.0 ± 0.1 ppb in 2024, which represents 125 % of the pre-industrial level (270.1 ppb).
• The annual increase was 1.0 ppb.
• The annual increase from 2023 to 2024 was slightly lower than the average growth rate over the past decade (1.07 ppb yr‐1).
• Global human-caused N2O emissions, dominated by nitrogen addition to cropland, have increased by 30 % over the past four decades.

Total radiation exposure

The cumulative impact of LLGHGs is measured by the NOAA Annual Greenhouse Gas Index (AGGI).

• AGGI reached a value of 2024 1,54.
• From 1990 to 2024, the total radiative forcing of LLGHGs increased by 54 %.
• Carbon dioxide (CO2) contributes approximately to this increase 81 %.

Given the dominant role of $\text{CO}_2}$ in global climate change, the main climate efforts must focus on achieving zero net anthropogenic CO2 emissionsExtending and strengthening greenhouse gas monitoring is key to understanding these feedbacks and supporting climate action. JRi