The Earth’s heat-trapping levels reached record highs in 2025, according to the United Nations’ World Meteorological Organisation (WMO). The UN World Meteorological Organisation weather and climate agency confirmed that the last year was the second or third hottest on record, at about 1.43 Celsius above the 1850-1900 average.
UN Secretary-General Antonio Guterres stated, “The global climate is in a state of emergency… Humanity has just endured the 11 hottest years on record.”
For the first time, the WMO report included the planet’s energy imbalance – the rate at which energy enters and leaves Earth system. The increase in concentrations of heat-trapping greenhouse gases like carbon dioxide, methane, and nitrous oxide to their highest level in at least 800,000 years has upset this equilibrium.
The Earth’s energy imbalance increased since its observational record began in 1960, particularly in the past 20 years. It reached a new high in 2025. WMO chief Celeste Saulo said scientific advances had improved understanding of the energy imbalance and its implications for the climate.
More than 91 per cent of excess heat is stored in the ocean. Ocean heat content reached a new record high in 2025, with its rate of warming more than doubled from 1960-2005 to 2005-2025. Ocean warming has far-reaching consequences such as degradation of marine ecosystems and reduction of the ocean carbon sink.
The Antarctic and Greenland ice sheets have both lost considerable mass, and the annual average extent of Arctic sea ice in 2025 was the lowest or second-lowest ever recorded in the satellite era. Global mean sea level was around 11 centimeters higher than when satellite altimetry records began in 1993.
WMO scientific officer John Kennedy said global weather is still under the influence of La Nina, a naturally occurring climate phenomenon that cools surface temperatures in the central and eastern equatorial Pacific Ocean. He forecast neutral conditions by middle of 2026 with a possible El Nino developing before end of year, which could lead to elevated temperatures again in 2027.
WMO Deputy Chief Ko Barrett said the outlook was dire. She stated that the WMO provided evidence hoping it would encourage people to take action. Guterres warned that climate stress is exposing another truth: our addiction to fossil fuels is destabilising both the climate and global security. He urged the world to heed the alarm call, stating that “climate chaos is accelerating and delay is deadly.”