The years between 2015 and 2025 were the warmest since records began in 1850, the World Meteorological Organization (WMO), an agency of the , announced today, with 2025 ranking second or third overall at about 1.43 degrees Celsius above the pre-industrial average.
This conclusion confirms a previous WMO report that 2025 was one of the three warmest years on record and that 2024 was the warmest year at about 1.55 degrees Celsius above the pre-industrial average.
“The global climate is in a state of emergency. Earth is being pushed beyond its limits. All key climate indicators are in the red,” warned UN Secretary-General Antonio Guterres on the occasion of the release of the WMO’s annual State of the Climate report.
For the first time, this report includes among the key climate indicators the Earth’s energy imbalance, which reflects the rate at which energy enters and leaves the planet’s system.
In a stable climate, the amount of solar energy entering is approximately equal to the amount of energy leaving. But this balance is being disrupted by increasing concentrations of greenhouse gases (CO2, methane and nitrous oxide), which are causing continuous warming of the atmosphere and oceans as well as melting of ice caps.
This imbalance has worsened since observations began in 1960, and particularly over the past 20 years, reaching a “new record in 2025,” the WMO notes.
“Human activities are increasingly disturbing the natural balance, and we will have to live with these consequences for hundreds, even thousands of years,” warns the organization’s secretary-general Celeste Saulo.
Heat in the ocean
In its report, the WMO confirms that the years 2015 to 2025 are the 11 warmest on record.
The year 2024, which began under the influence of a strong El Niño phenomenon, remains the warmest year on record, the organization further emphasizes.
“Extreme events occurring around the world, including extreme heat events, heavy rainfall and tropical cyclones, have caused disruption and damage and highlighted the vulnerability of our interconnected economies and societies,” WMO notes.
cause a long-term rise in global mean sea level, which has accelerated since satellite measurements began in 1993. In 2025, this level was projected to be about 11 cm higher than at the start of record-keeping.
91% of excess heat is stored in the ocean, which acts as a buffer against rising temperatures on land. However, according to the WMO, “ocean heat content reached a new record in 2025 and the rate of warming more than doubled between the periods 1960-2005 and 2005-2025.”
At the same time, the Antarctic and Greenland ice sheets have lost significant mass, and the average annual extent of Arctic sea ice in 2025 ranks among the first or second lowest ever measured since the beginning of the satellite era, the United Nations agency notes.
Climate chaos
John Kennedy, a WMO expert, told the press that the climate remains under the influence of a La Niña phenomenon, which is associated with lower global temperatures.
“Forecasts generally show a return to neutrality by mid-year, with a possible El Niño later in the year (…) We could therefore see a further rise in temperatures in 2027,” he explained, adding that nothing is certain at this stage.
“Let’s be honest, the situation is rather alarming (…) We are using this information to improve our forecasts and to justify the need for early warning systems to do what we can to mitigate the consequences, but (…) these indicators are not trending in a direction that suggests a favorable outcome,” WMO Deputy Secretary-General Ms Barrett told the press.
“The report published today should come with a warning: climate chaos is accelerating and any further delay will be fatal,” Antonio Guterres concluded.
