The Earth’s climate is more out of balance than at any time in observed history, as greenhouse gas concentrations drive continued warming of the atmosphere and ocean and melting of ice, according to the World Meteorological Organisation (WMO). These rapid and large-scale changes have occurred within a few decades but will have harmful repercussions for hundreds, and potentially thousands, of years.
WMO’s 2025 report (WMO’s State of the Global Climate report 2025) published on 23 March, confirms that the years 2015-2025 were the hottest 11 years on record, and that 2025 was the second or third hottest year on record, at about 1.43 °C above the 1850-1900 average. Extreme events around the world, including intense heat, heavy rainfall and tropical cyclones, caused disruption and devastation and highlighted the vulnerability of our inter-connected economies and societies.
Go deeper with GlobalData
Discover B2B Marketing That Performs
Combine business intelligence and editorial excellence to reach engaged professionals across 36 leading media platforms.
The ocean continues to warm and absorb carbon dioxide. It has been absorbing the equivalent of about eighteen times the annual human energy usage each year for the past two decades. Annual sea ice extent in the Arctic was at or near a record low, Antarctic sea ice extent was the third lowest on record, and glacier melt continued unabated, according to the report.
“The State of the Global Climate is in a state of emergency. Planet Earth is being pushed beyond its limits. Every key climate indicator is flashing red,” said UN secretary-general António Guterres. “Humanity has just endured the eleven hottest years on record. When history repeats itself eleven times, it is no longer a coincidence. It is a call to act.”
Imbalance
For the first time, the report includes the Earth’s energy imbalance as one of the key climate indicators. It measures the rate at which energy enters and leaves the Earth system. Under a stable climate, incoming energy from the sun is about the same as the amount of outgoing energy.
However, increasing concentrations of heat-trapping greenhouse gases – carbon dioxide, methane and nitrous oxide – to their highest level in at least 800 000 years have upset this equilibrium.The Earth’s energy imbalance has increased since its observational record began in 1960, particularly in the past 20 years. It reached a new high in 2025.
“Scientific advances have improved our understanding of the Earth’s energy imbalance and of the reality facing our planet and our climate right now,” said WMO secretary-general Celeste Saulo. “Human activities are increasingly disrupting the natural equilibrium and we will live with these consequences for hundreds and thousands of years.”
“On a day-to-day basis, our weather has become more extreme. In 2025, heatwaves, wildfires, drought, tropical cyclones, storms and flooding caused thousands of deaths, impacted millions of people and caused billions in economic losses,” said professor Saulo.
Atmospheric warming
The warming of the atmosphere including that near the Earth’s surface represents just 1% of the excess energy, whilst about 5% is stored in the continental land masses. More than 91% of the excess heat is stored in the ocean, which acts as a major buffer against higher temperatures on land. Ocean heat content reached a new record high in 2025 and its rate of warming more than doubled from 1960-2005 to 2005-2025.
Another 3% of the excess energy warms and melts ice. The ice sheets on Antarctica and Greenland have both lost significant mass and the annual average Arctic sea-ice extent for 2025 was the lowest or second lowest on record in the satellite era. The warming ocean and melting ice are driving the long-term rise in global mean sea level, which has accelerated since satellite measurements began in 1993.
Ocean warming and sea level rise will continue for centuries, according to projections by the Intergovernmental Panel on Climate Change (IPCC). Changes in ocean warming, and deep ocean pH are irreversible on centennial to millennial time scales.
Impact on health
The report includes a chapter on climate and health, showing how rising temperatures, shifting rainfall patterns and changes in extremes are affecting where and when health risks emerge, how severe they become and who is most exposed. It highlights the examples of the mosquito-borne dengue disease and of heat stress – and illustrates how climate data, early warning systems and integrated climate services for health can protect people in a warming world.
“In this age of war, climate stress is also exposing another truth: our addiction to fossil fuels is destabilising both the climate and global security. [This] report should come with a warning label: climate chaos is accelerating and delay is deadly,” said Mr Guterres.
Key indicators
- Data from individual monitoring stations show that levels of three main greenhouse gases – carbon dioxide, methane and nitrous oxide – continued to increase in 2025.
- The past eleven years, 2015–2025, were the eleven warmest years on record. The year 2024 – which started with a strong El Niño – remains the warmest year, at about 1.55 °C above the 1850–1900 average.
- In 2025, ocean heat content (to a depth of 2000 metres) reached the highest level since the start of records in 1960, exceeding the previous high set in 2024. Over the past nine years, each year has set a new record for ocean heat content.
- In 2025, global mean sea level was comparable to the record-high levels observed in 2024. It was around 11 cm higher than at the start of the satellite altimetry record in 1993.
- Around 29% of the CO2 from human activities between 2015–2024 was absorbed by the ocean, leading to the continued decline in ocean surface pH. Global average ocean surface pH has declined over the past 41 years. There is very high confidence that present-day surface pH values are unprecedented for at least 26 000 years, according to the IPCC.
- In the 2024/2025 hydrological year, glacier mass loss from reference glaciers was among the five worst on record. This continues a trend of accelerated glacier mass loss since records started in 1950.
- The annual average Arctic sea-ice extent for 2025 was the lowest or second lowest on record in the satellite era (1979). The maximum daily extent of Arctic sea-ice (after the winter freeze) in 2025 was the lowest annual maximum in the observed record (since 1979) at about 14.19 million km2.
- Extreme weather has cascading impacts on agricultural production. Climate-driven food insecurity is now seen as a risk.
- Climate change has wide-ranging impacts on mortality, livelihoods, ecosystems and health systems and amplifies risks such as vector- and water-borne diseases and mental health stressors. Dengue stands out as the world’s fastest-growing mosquito-borne disease. According to the World Health Organization, about half the world’s population is at risk. Heat stress – over one-third of the global workforce, 1.2 billion people, face workplace heat risk at some point each year, especially those in agriculture and construction.
To view the report visit: https://wmo.int/publication-series/state-of-global-climate/state-of-global-climate-2025
