South Korea’s CO₂ levels hit record high

South Korea’s atmospheric carbon dioxide concentration reached a record high last year, raising fresh concerns that the country is lagging behind its climate commitments despite repeated government pledges to cut greenhouse gas emissions, according to official monitoring data.

The average concentration of atmospheric carbon dioxide in South Korea rose to 432.7 parts per million (ppm) in 2025, the highest level since measurements began in 1999, according to the 2025 Global Atmosphere Watch Report released on April 29 by the National Institute of Meteorological Sciences, Korean media writes. 

This figure also exceeded the global average of 425.6 ppm recorded last year, underscoring a widening gap between domestic and global trends.

The report shows that the increase in South Korea’s CO₂ levels is outpacing the global average. While global concentrations rose by 2.8 ppm compared with the previous year, South Korea recorded a higher increase of 3.2 ppm. Over the longer term, from 2000 to 2025, global CO₂ levels rose by an average of 2.3 ppm annually, compared with 2.5 ppm in South Korea.

The findings highlight what analysts describe as a persistent disconnect between policy goals and actual emissions performance.

South Korea ranked 63rd out of 67 countries in the Climate Change Performance Index report released in November, reflecting weak progress in decarbonisation efforts. The report urged Seoul to prioritise implementation over target-setting, citing its relatively low share of renewable energy and an oversupplied emissions trading system.

Other greenhouse gases also reached new highs in 2025. The average concentration of nitrous oxide rose to 340.6 parts per billion (ppb), an increase of 1.2 ppb from the previous year, while sulfur hexafluoride climbed to 12.5 parts per trillion (ppt), up 0.3 ppt. Both levels were higher than global averages.

Sulfur hexafluoride is particularly concerning due to its extremely long atmospheric lifespan, making it one of the most persistent and potent greenhouse gases once released.

Rising emissions are also being reflected in temperature trends. South Korea’s average annual temperature reached 13.5 degrees Celsius (56.3 degrees Fahrenheit) last year, 1.4 degrees higher than the 1973–1999 average of 12.1 degrees.

Despite the overall upward trend, the report also noted some areas of improvement. Levels of chlorofluorocarbons (CFCs), which damage the ozone layer and contribute to warming, continued to decline. Domestic concentrations of CFC-11 and CFC-12 fell by 4.8 ppt and 3.1 ppt respectively, supporting gradual recovery of the ozone layer, according to the Korea Meteorological Administration (KMA).

Methane levels also reached a record high of 2,023 ppb, but the rate of increase slowed significantly. The annual rise was just 2 ppb, compared with an average increase of 10 ppb between 2015 and 2024. Methane is a potent greenhouse gas with a warming effect 27.9 times stronger than carbon dioxide.

The KMA said the slowdown in some greenhouse gases may reflect the impact of international and domestic policy measures, including the global ban on CFCs under the 1989 Montreal Protocol, which came into force in 2010.

“Methane also has a much shorter atmospheric lifetime than carbon dioxide, so the effects of policy-driven reductions can appear relatively quickly,” said Kim Sang-baek, head of the Global Atmosphere Watch Research Division at the National Institute of Meteorological Sciences. “We are conducting a more detailed analysis of the factors behind the slowdown in its growth.”

By Sabina Mammadli