Greenhouse gases, sea level hit record highs in 2025, report finds

The American Meteorological Society on Monday published its 36th annual State of the Climate report, confirming that greenhouse gas concentrations, global sea level, and ocean heat content all reached record highs in 2025. The peer-reviewed report, based on contributions from 625 scientists in 60 countries, offers the most comprehensive annual assessment of the planet's climate indicators.eurekalert+1

Carbon dioxide levels reached a globally averaged 425.6 parts per million in 2025 — a 53% increase from the pre-industrial level of roughly 278 parts per million. Fossil fuel emissions also hit a record, estimated at 10.3 petagrams of carbon per year, more than three times the rate measured in the 1960s.eurekalert

Warming and Ocean Records

The 2025 global mean temperature ranked among the three highest years on record, with datasets stretching back to the mid-1800s. All five major global temperature datasets used in the report agree that the last 11 years — 2015 through 2025 — were the 11 warmest on record. Notably, 2025 was the warmest year in which no El Niño conditions were present.eurekalert

The oceans continued to absorb the bulk of excess heat trapped by greenhouse gases. Ocean heat content, measured from the surface to a depth of 2,000 meters, reached a new record. Global mean sea level was a record high for the 14th consecutive year, reaching about 111.2 millimeters above the 1993 average, when satellite altimetry measurements began. The World Meteorological Organization's own climate report earlier this year similarly noted that the ocean has been absorbing energy equivalent to about 18 times annual human energy use each year over the past two decades.wmo+1

Ice Loss and Extreme Weather

The Arctic had its second-warmest year in the 126-year record, with surface air temperatures increasing at roughly three times the global average rate. Maximum Arctic sea ice extent in 2025 was the lowest in the 47-year record, while ice older than four years has nearly vanished — just 95,000 square kilometers remained in September 2025, compared with 1.5 million square kilometers in the 1980s.eurekalert

Antarctica observed its warmest year since records began in 1979, and land-based glaciers lost ice for the 38th consecutive year, with about 41% of total glacier loss since 1976 occurring in the last decade alone.eurekalert

Tropical cyclone activity was above average, with 97 named storms globally compared to a 1991–2020 average of 87. Hurricane Melissa became one of the strongest Atlantic hurricanes on record, making landfall in Jamaica as a Category 5 storm with maximum sustained winds of 190 miles per hour, causing 95 fatalities and at least $12.2 billion in damage.eurekalert

"Consider it analogous to your annual health assessment from your physician," said AMS President Alan Sealls. "The State of the Climate connects to the health of all ecosystems."eurekalert