Greenhouse gas levels reach record high in 2025, WMO report warns

Atmospheric concentrations of carbon dioxide (CO2) and other major greenhouse gases reached record highs in 2025, the World Meteorological Organization (WMO) warned on Wednesday, November 4, 2026. The WMO’s latest Greenhouse Gas Bulletin, released on October 27, 2026, indicates that this will lead to a sustained increase in global temperatures.The global average concentration of CO2 in the atmosphere reached 426.8 parts per million (ppm) in 2025. This represents a 153 percent increase compared to pre-industrial levels in 1750. Methane and nitrous oxide, the second and third most significant greenhouse gases directly linked to human activities, also hit new record levels in 2025, reaching 1,948 ppm and 339.1 ppm respectively. These figures are 267 percent and 126 percent higher than pre-industrial levels.Ko Barrett, Deputy Secretary-General of the WMO, stated that the continuous record-breaking levels of greenhouse gases have trapped the highest amount of heat in the atmosphere to date. This has resulted in extreme weather events and increased risks to economies and societies. Barrett noted that the past 11 years have been the warmest on record, a trend expected to continue. She emphasized that CO2 remains in the atmosphere for extended periods, impacting the global climate for years, decades, and even centuries.The WMO publishes its Greenhouse Gas Bulletin annually to provide official scientific information to negotiators at the United Nations climate conferences. The 31st Conference of the Parties (COP31) to the United Nations Framework Convention on Climate Change (UNFCCC) is scheduled to take place in Antalya, Turkey, from November 9 to 20, 2026, with the goal of translating climate commitments into concrete actions. Pre-sessional meetings for COP31 are currently underway from November 2 to 8, 2026, and heads of state will participate in a World Leaders’ Summit in Antalya on November 11 and 12.The bulletin details annual greenhouse gas emissions and the average accumulation of gases in the atmosphere. Approximately half of the total CO2 emitted each year remains in the atmosphere, while the rest is absorbed by terrestrial ecosystems and oceans. When the bulletin was first published in 2004, the annual average CO2 concentration measured by WMO’s Global Atmosphere Watch Programme stations was 377.5 ppm.According to the annual Greenhouse Gas Index by the National Oceanic and Atmospheric Administration (NOAA) of the United States, the warming effect on the climate system from long-lived greenhouse gases increased by 56 percent between 1990 and 2025, with CO2 contributing approximately 81 percent of this increase.Since the 1960s, the rate of CO2 increase has tripled. In the 1960s, the annual average increase was 0.8 ppm, which rose to 2.4 ppm per year in the decade from 2011 to 2020. From 2024 to 2025, the global average CO2 concentration in the atmosphere increased by 2.8 ppm. While this is higher than the average for the last decade, it is slightly less than the exceptional increase observed from 2023 to 2024.Scientists attribute the slightly lower growth rate from 2024 to 2025 to improvements in land-based carbon absorption systems and a reduction in carbon emissions from wildfires, following the powerful El Niño event of 2023–2024. However, CO2 concentrations in the atmosphere are expected to increase further in 2026 due to continued fossil fuel use and the development of a powerful El Niño. Scientists warn that El Niño could affect land-based carbon absorption capacity, similar to its impact in 2023–2024, and the changing climate increases the risk of reduced ocean carbon absorption capacity.The agricultural sector in Madhesh Province, for instance, faces severe challenges due to climate change and flooding, according to the Nepal Rastra Bank’s annual study report for 2082/83 (2025/26). Irrigated areas in Madhesh Province decreased by 4.34 percent to 244,725 hectares in 2025/26. This decline in irrigated land has led to increased production costs and reduced productivity. The province is highly vulnerable to various natural disasters, including floods, droughts, storms, and cold waves.In 2025, Madhesh Province experienced a severe drought due to extreme heat and a delayed monsoon, which led to the drying up of tube wells and deep bore wells, failure of irrigation systems, and loss of agricultural activities. The province was formally declared a drought-affected area in 2025, and the federal government escalated the crisis to a disaster emergency on July 23. The severe water shortage in Madhesh Province began in July 2025, necessitating the provincial government to supply drinking water via fire trucks. Over the past three years, a reduction in monsoon rainfall has caused 30 to 40 percent of handpumps in Madhesh to dry up during winter months, and groundwater levels in many districts in the western and central parts of the province have dropped by more than three meters.