Greenhouse gas concentrations, global sea level and ocean heat content all reached record highs in 2025, according to the 36th annual International "State of the Climate" report, released August 10, 2026. The peer-reviewed assessment, published as a supplement to the Bulletin of the American Meteorological Society (BAMS), draws on contributions from 625 scientists in 60 countries.

Key findings: the globally averaged CO2 concentration reached 425.6 parts per million — 53% above the pre-industrial level of about 278 ppm — while fossil fuel emissions hit an estimated record of 10.3 petagrams of carbon per year. 2025 ranked among the three warmest years on record and was the warmest year ever observed without an El Niño, since the eastern Pacific was in a cool, La Niña-like state for much of the year. Europe had its warmest year on record; Russia, China, South Korea and Argentina each reported their second warmest. All five major global temperature datasets agree that 2015–2025 were the 11 warmest years on record.

The oceans kept absorbing the vast majority of the planet's excess heat: ocean heat content measured to a depth of 2,000 meters reached a new record, and global mean sea level hit a record for the 14th consecutive year — about 111.2 millimeters above the 1993 baseline. Approximately 87% of the ocean surface experienced at least one marine heatwave during the year. In the Arctic, the annual maximum sea ice extent was the lowest in 47 years, and Antarctica logged its warmest year since records began in 1979.

Land glaciers lost ice for the 38th consecutive year, shedding the equivalent of more than one meter of water on average for the fourth straight year; about 41% of all glacier loss since 1976 has occurred in the past decade. Tropical cyclone activity was above average, with 97 named storms against a 1991–2020 average of 87. Five storms reached Category 5 intensity, including Hurricane Melissa — one of the strongest Atlantic hurricanes on record, peaking at 190 miles per hour and 892 hPa before its Category 5 landfall in Jamaica, which killed 95 people and caused at least $12.2 billion in damage.

AMS President Alan Sealls called the report a "comprehensive, collaborative international effort" that works like an annual physical for the planet — "critical measurements and trends which inform agencies, communities, businesses, and individuals for long-term planning."

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