Planet-heating gases smash records AGAIN – and UN warns they’ll climb even higher in 2026

The gases heating our planet have climbed to yet another all-time high, and the United Nations’ weather agency is warning they are set to go even higher this year.

The World Meteorological Organization’s annual Greenhouse Gas Bulletin, published on 27 October, found that the three main long-lived greenhouse gases, carbon dioxide, methane and nitrous oxide, all reached record concentrations in the atmosphere in 2025. The report lands less than a fortnight before world leaders and negotiators gather for the COP31 climate summit in Antalya, Türkiye, from 9 to 20 November.

The numbers behind the warning

According to the WMO, the global average concentration of carbon dioxide reached 426.8 parts per million (ppm) in 2025. That is 153 per cent of the level before the industrial era, taken as the year 1750.

The rise from 2024 to 2025 was 2.8 ppm. That is higher than the average yearly increase over the past decade, though smaller than the exceptional jump seen between 2023 and 2024.

Methane, a powerful but shorter-lived warming gas, hit 1,948 parts per billion, which the WMO says is 267 per cent of pre-industrial levels. About 65 per cent of methane emissions come from human activities such as livestock farming, rice growing, fossil fuel extraction, landfills and burning biomass.

Nitrous oxide, linked to fertiliser use, industry and burning, reached 339.1 parts per billion, 26 per cent above its 1750 level.

WMO Deputy Secretary-General Ko Barrett summed it up bluntly: “Another year, another new record.”

Why the rise slowed slightly

The slightly smaller increase in CO2 last year is not evidence that emissions are falling. The WMO said burning fossil fuels remains the main driver of the build-up.

Instead, the agency’s scientists linked the smaller jump to natural factors. The strong El Niño of 2023 and 2024 had weakened the ability of forests and other land ecosystems to soak up carbon, and fuelled large wildfires. In 2025 those land “carbon sinks” partially recovered and fire emissions fell, so more CO2 was absorbed.

Roughly half of the CO2 humans emit each year is taken up by land ecosystems and the oceans, according to the bulletin. Any weakening of those natural sponges means more stays in the atmosphere.

Alex Vermeulen, director of the Carbon Portal at the European research network ICOS, which supplies measurements from more than 40 atmospheric stations across Europe to the bulletin, said scientists still see no decline in the rate at which CO2 is growing in the atmosphere.

A longer view

The bigger picture is stark. The annual growth rate of CO2 has roughly tripled since the 1960s, from around 0.8 ppm a year to 2.4 ppm a year in the decade 2011 to 2020. Between 1990 and 2025, the warming effect of long-lived greenhouse gases rose by 56 per cent, with carbon dioxide responsible for around 81 per cent of that increase, based on figures from the US National Oceanic and Atmospheric Administration cited by ICOS.

The past 11 years have been the warmest on record, the WMO said.

The bulletin also flagged a couple of lesser-known threats. It said sulphur hexafluoride, a potent gas used in electrical equipment, and leaks of hydrogen could erode some of the benefits of the switch to clean energy if not managed carefully.

What happens next

The WMO expects CO2 concentrations to rise again in 2026. It points to continued fossil fuel burning and a developing El Niño that could, as last time, weaken the land’s ability to absorb carbon. The agency also warned that reduced uptake of CO2 by the oceans is a growing risk.

The bulletin is designed to feed directly into the COP31 negotiations in Antalya, where countries will be under pressure to show how they plan to cut emissions. For Ireland, which like other EU members will be represented at the summit through the European Union’s negotiating bloc as well as its own delegation, the findings add to a familiar message: the concentrations in the air will only stop rising when emissions fall close to zero.

Sources

• World Meteorological Organization: Greenhouse gas levels once again reach record high (27 October 2026)
• ICOS: Greenhouse gas levels once again reach record high (27 October 2026)

Featured image: photo by Daniel Moqvist on Unsplash.