WMO releases 22nd Greenhouse Gas Bulletin

All three major greenhouse gases reach highest levels on record

A pedestrian walks with an umbrella past a climate clock installed at Dongdaegu Station plaza on Aug. 28. The clock counts down the time remaining before the global average temperature rises 1.5 degrees Celsius above pre-industrial levels, based on cumulative carbon dioxide emissions. Scientists warn that exceeding 1.5 degrees significantly increases the risk of climate disasters. [Yonhap]
A pedestrian walks with an umbrella past a climate clock installed at Dongdaegu Station plaza on Aug. 28. The clock counts down the time remaining before the global average temperature rises 1.5 degrees Celsius above pre-industrial levels, based on cumulative carbon dioxide emissions. Scientists warn that exceeding 1.5 degrees significantly increases the risk of climate disasters. [Yonhap]

Global concentrations of carbon dioxide, methane and nitrous oxide all reached record highs last year.

The Korea Meteorological Administration said Tuesday that the World Meteorological Organization's Greenhouse Gas Bulletin No. 22 showed average global concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in 2025 stood at 426.8 parts per million, 1,948 parts per billion and 339.1 parts per billion, respectively — each the highest ever recorded.

All three gases have surpassed any previously observed level. Compared with pre-industrial levels in 1750, CO2 concentrations are now roughly 1.5 times higher, methane 2.7 times higher and nitrous oxide 1.3 times higher.

CO2 concentrations rose by 2.8 ppm over the course of 2025, a smaller increase than the 3.5 ppm recorded the previous year. The WMO attributed the slowdown to land ecosystems — forests and soils — recovering their capacity to absorb CO2 following the strong El Niño of 2023–2024, as well as a reduction in carbon emissions from wildfires.

Methane concentrations increased by 6 ppb, below the 10 ppb annual average over the past decade. Nitrous oxide rose by 1.1 ppb, roughly in line with its 10-year average annual increase.

South Korea's greenhouse gas levels above global average

South Korea's greenhouse gas concentrations also exceeded the global average. Background concentration figures released by the Korea Meteorological Administration in April showed 2025 levels of 432.7 ppm for CO2, 2,023 ppb for methane and 340.6 ppb for nitrous oxide — higher than the global averages by 5.9 ppm, 75 ppb and 1.5 ppb, respectively.

Background concentration refers to measurements taken to minimize the influence of localized pollution sources and capture the overall level of greenhouse gases in the atmosphere. Over the past decade, South Korea's annual average increases in greenhouse gas concentrations were 2.7 ppm for CO2, 9 ppb for methane and 1.2 ppb for nitrous oxide.

The bulletin also examined the climate impact of sulfur hexafluoride (SF6) and hydrogen (H2), both used in the energy transition. SF6 is primarily used as an insulating gas in electrical equipment to prevent leakage and arcing. Once released into the atmosphere, it can persist for more than 1,000 years and has a global warming potential 24,300 times greater than CO2 over a 100-year period.

Hydrogen is not itself a greenhouse gas, but it can slow the breakdown of atmospheric methane, indirectly contributing to global warming. The WMO noted that if both gases leak into the atmosphere during the energy transition, they could partially offset the intended greenhouse gas reduction benefits.

SF6 concentrations have risen continuously over the past three decades, according to the WMO. The annual increase in 2025 was the largest ever recorded.

Korea Meteorological Administration Commissioner Lee Mi-seon said long-term greenhouse gas observation data serve as a critical scientific basis for understanding the causes and trends of climate change. "We will deepen scientific understanding of greenhouse gas changes both globally and in South Korea, and support the country's carbon neutrality policy," she said.


newday@heraldcorp.com