WMO Greenhouse Gas Bulletin 2026: Record CO2 at 426.8 ppm, Methane and N2O Explained

What happened

The World Meteorological Organization (WMO) released its Greenhouse Gas Bulletin No. 22 in Geneva. WMO's press release and the bulletin page are both dated 27 October 2026. The bulletin reports that the three main long-lived greenhouse gases (carbon dioxide, methane and nitrous oxide) all reached new record concentrations in 2025.

• Carbon dioxide (CO2): global average surface concentration of 426.8 ppm in 2025, which is 153% of the pre-industrial (1750) level.
• Methane (CH4): 1948 ppb, or 267% of the 1750 level.
• Nitrous oxide (N2O): 339.1 ppb, or 126% of the 1750 level (26% higher).

CO2 rose by 2.8 ppm from 2024 to 2025. WMO said this was slightly less than the exceptional surge of 2023/2024 but above the 2016-2025 average annual growth rate.

"Another year, another new record," said WMO Deputy Secretary-General Ko Barrett, adding that greenhouse gases are trapping an unprecedented amount of heat and so supplying energy for more extreme weather.

Background

The Greenhouse Gas Bulletin is one of WMO's flagship annual publications. It reports atmospheric concentrations (what stays in the air), not emissions (what is released). Its data come from WMO's Global Atmosphere Watch (GAW) network; WMO says 179 stations were used for the CO2 analysis. GAW data are archived by the World Data Centre for Greenhouse Gases, run by the Japan Meteorological Agency. The previous edition, No. 21, came out on 16 October 2025.

WMO notes that CO2 growth rates have tripled since the 1960s, from 0.8 ppm per year to 2.4 ppm per year in 2011-2020. In 2004, the annual average CO2 concentration was 377.5 ppm.

Key details

Why CO2 growth slowed a little. WMO senior scientific officer Oksana Tarasova said the more modest 2024-2025 growth reflected recovery of land carbon sinks and lower fire emissions in 2025, after the strong 2023/2024 El Nino had reduced the efficiency of the biosphere through drought, drier vegetation and wildfires. She added that a 2.8 ppm rise is still a substantial addition of carbon from fossil fuel burning.

Outlook for 2026. Tarasova said a further increase is expected in 2026 because of fossil fuel burning and a developing powerful El Nino that will affect land carbon sinks. She also warned that risks of reduced CO2 uptake by the ocean are increasing.

Heat-trapping effect. Citing NOAA's Annual Greenhouse Gas Index, WMO says radiative forcing from long-lived greenhouse gases rose 56% between 1990 and 2025, with CO2 responsible for about 81% of that increase. Since pre-industrial times, CO2 accounts for 66% of the forcing, methane 16%, N2O 6%, CFCs 8%, and HCFCs and HFCs 2% each.

Methane sources. About 35% of methane comes from natural sources such as wetlands and about 65% from human activities such as cattle, rice farming, fossil fuel exploitation, landfills and biomass burning.

Other gases. Sulphur hexafluoride (SF6), used as a spark suppressant in electricity distribution, recorded a record increase in 2025. It lasts over 1,000 years in the air and has a 100-year warming potential about 24,300 times that of CO2. Hydrogen (H2) concentration rose 5.3% between 2010 and 2024; it is not a greenhouse gas itself but, according to WMO, has a strong indirect warming effect through atmospheric chemistry.

Why it matters

• Long-lasting warming: Barrett noted that CO2 has a very long lifetime and will affect the climate for decades and even centuries. She added that the past 11 years have been the warmest on record.
• Input for negotiators: WMO releases the bulletin to give scientific information to negotiators at the UN climate conference, this year COP 31 in Antalya, Turkiye (9-20 November 2026), which WMO says seeks to turn climate commitments into concrete actions.
• India link: On 25 March 2026 the Union Cabinet approved India's NDC for 2031-2035, to be sent to the UNFCCC. As per PIB, it targets a 47% cut in emissions intensity of GDP by 2035 from 2005 levels, 60% non-fossil share of installed power capacity by 2035, and a carbon sink of 3.5-4.0 billion tonnes of CO2 equivalent through forest and tree cover by 2035, within the goal of net zero by 2070.

Issues and criticism

• Weakening sinks: WMO flags that land and ocean sinks, which absorb part of human CO2, are vulnerable to El Nino, drought and a warming climate.
• Concentration vs emissions: a slower rise in one year does not mean emissions have fallen; it can reflect natural swings in sinks and fires, as WMO's explanation of 2025 shows.
• New pressures: WMO links rising SF6 to electrification, a reminder that the energy transition has its own side effects.

Way forward

• Cut fossil fuel emissions, the main source of the CO2 rise according to WMO.
• Target methane and N2O from agriculture, waste and energy.
• Expand greenhouse gas monitoring so that sinks and sources are tracked with accuracy.
• Turn national commitments into concrete action, the aim WMO attaches to COP 31.

Revise this and other October stories with the weekly current affairs quiz, and see the UPSC Prelims page for the syllabus.

Prelims pointers

• The Greenhouse Gas Bulletin is published by the WMO (headquarters: Geneva); No. 22 was released on 27 October 2026.
• CO2 in 2025: 426.8 ppm, 153% of the 1750 level.
• Methane in 2025: 1948 ppb (267% of 1750); N2O: 339.1 ppb (126% of 1750).
• CO2 rose 2.8 ppm from 2024 to 2025.
• Data source: WMO's Global Atmosphere Watch network.
• CO2 accounts for 66% of radiative forcing by long-lived greenhouse gases since pre-industrial times.
• SF6 has a lifetime of over 1,000 years and a 100-year warming potential about 24,300 times CO2.

One-liners for SSC, Banking and Railways

• WMO's Greenhouse Gas Bulletin No. 22 reported record CO2 of 426.8 ppm in 2025.
• Methane concentration in 2025: 1948 ppb.
• Nitrous oxide concentration in 2025: 339.1 ppb.
• Greenhouse gas data for the bulletin come from the Global Atmosphere Watch network.
• India's net zero target year: 2070.

Mains practice question

Q. "Record greenhouse gas concentrations show that natural carbon sinks cannot be taken for granted." Discuss in the light of the WMO Greenhouse Gas Bulletin 2026. (250 words, GS III)

Points to cover:

1. Key findings: record CO2, CH4 and N2O in 2025; 2.8 ppm CO2 rise.
2. Role of land and ocean sinks; effect of the 2023/2024 El Nino, drought and wildfires.
3. Difference between emissions and concentrations; long lifetime of CO2.
4. Policy response: India's 2035 NDC and net zero 2070; global action at COP 31.