Greenhouse Gases, Sea Level, and Ocean Heat Hit Record Highs in 2025
Earth’s major climate indicators continued to move into unprecedented territory in 2025, according to the newly released 36th annual State of the Climate report from the Bulletin of the American Meteorological Society. The peer-reviewed assessment, produced with contributions from 625 scientists in 60 countries, draws on observations from land, oceans, ice, and space to provide what the American Meteorological Society (AMS) describes as an annual physical of the global climate.
Key data from the report include:
Major greenhouse gases reached global highs in 2025: The average concentration of atmospheric carbon dioxide (CO₂) reached a record 425.6 ± 0.1 ppm in 2025—about 53% above the preindustrial concentration of approximately 278 ppm. Methane and nitrous oxide also reached record concentrations, standing approximately 166% and 26% above preindustrial levels, respectively.
Global fossil-fuel carbon emissions reached a record estimated 10.3 ± 0.5 petagrams of carbon per year in 2025, more than three times the roughly 3.0 ± 0.2 petagrams emitted annually during the 1960s.
All five major global temperature datasets assessed in the report agree that 2015 through 2025 were the 11 warmest years on record. The global land-and-ocean temperature in 2025 ranked among the three warmest in records in more than 175 years.
The year 2025 was the warmest on record without El Niño conditions. Europe experienced its warmest year on record, while Russia, China, South Korea, and Argentina each recorded their second-warmest year.
The annual global sea-surface temperature was 0.38°C (0.68°F) above the 1991–2020 average, making 2025 the third-warmest year in a 172-year record despite relatively cool conditions in the equatorial Pacific.
Over the past half-century, the oceans have absorbed nearly 90% of the excess energy trapped in Earth's climate system. Ocean heat content from the surface down to 2,000 meters (about 6,560 feet) reached another record high in 2025.
Global mean sea level reached a record 111.2 mm (4.38 inches) above the 1993 average, marking the 14th consecutive year in which satellite-era global sea level set a record high.
The Arctic experienced its second-warmest year in a 126-year record. Arctic surface air temperatures are increasing at approximately three times the global average rate.
Arctic maximum sea-ice extent was the lowest in the 47-year satellite record. By September 2025, only about 95,000 square kilometers (36,700 square miles) of Arctic sea ice more than four years old remained, compared with roughly 1.5 million square kilometers (579,000 square miles) during the 1980s—a decline of more than 90%.
Antarctica experienced its warmest year since records began in 1979. Antarctic sea ice also remained unusually low, with the year's maximum extent ranking third lowest and its minimum extent fourth lowest on record.
The world's land-based glaciers recorded a negative annual mass balance for the 38th consecutive year. For the fourth year in a row, glaciers lost the equivalent of more than 1 meter (3.3 feet) of water thickness on average.
Since 1970, glaciers have lost approximately 9,000 gigatons of water, with about 41% of that loss occurring during just the past decade.
Carbon emissions from global fires fell 26% from 2024 and reached their lowest level since the record began in 2003. Africa, responsible for roughly 40% of global fire emissions, recorded its lowest emissions in the dataset, as did South America. However, severe forest-fire activity persisted in regions including Canada and the European Union.
Canada experienced its second-worst wildfire season on record, with approximately 8.9 million hectares (22 million acres) burned over five months. Another roughly 2 million hectares (4.9 million acres) burned across the contiguous United States.
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