Earth’s climate swings increasingly out of balance
Geneva, Switzerland (WMO) – 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 Organization (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 State of Climate report confirms 2015-2025 hottest 11 years on record
- Earth’s energy imbalance is highest in sixty five-year record
- The ocean has been absorbing about eighteen times the annual human energy use each year for the past two decades
- Extreme weather impacts millions and costs billions
- World Meteorological Day: observing today to protect tomorrow
WMO’s State of the Global Climate report 2025 confirms that 2015-2025 are 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.
The ocean continues to warm and absorb carbon dioxide. It has been absorbing the equivalent of about eighteen times the annual human energy use 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,” said Mr Guterres.
WMO’s flagship State of the Global Climate report was released on World Meteorological Day on 23 March, which has the theme Observing Today, Protecting Tomorrow.
For the first time, the report includes the Earth’s energy imbalance as one of the key climate indicators.
The Earth’s energy balance 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 Celeste Saulo.
The warming of the atmosphere including near the Earth’s surface (the temperatures that humans feel) 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. Exceptional glacier mass loss occurred in Iceland and along the Pacific coast of North America in 2025.
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.
The report is accompanied by an interactive story map. It has a dedicated supplement on extreme events, highlighting their cascading impacts, including on food insecurity and displacement.
It 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.
“And in this age of war, climate stress is also exposing another truth: our addiction to fossil fuels is destabilizing both the climate and global security. Today’s report should come with a warning label: climate chaos is accelerating and delay is deadly,” said Mr Guterres.
The State of the Global Climate report 2025 is based on scientific contributions from National Meteorological and Hydrological Services, WMO Regional Climate Centres, United Nations partners and dozens of experts.
“WMO’s State of the Global Climate report seeks to inform decision-making. It is in keeping with the theme of World Meteorological Day because when we observe today, we don’t just predict the weather, we protect tomorrow. Tomorrow’s people. Tomorrow’s planet,” said Celeste Saulo.
Key Indicators
Greenhouse Gases
Data from individual monitoring stations show that levels of three main greenhouse gases – carbon dioxide, methane and nitrous oxide – continued to increase in 2025.
In 2024 – the last year for which we have consolidated global observations - the atmospheric concentration of carbon dioxide reached its highest level in the last 2 million years, and methane and nitrous oxide in at least last 800 000 years.
The increase in the annual carbon dioxide concentration (CO2) in 2024 was the largest annual increase since modern measurements began in 1957. This was driven by continued fossil CO2 emissions, and reduced effectiveness of land and ocean carbon sinks.
Global mean near-surface temperature
The past eleven years, 2015–2025, were the eleven warmest years on record.
2025 was the second or third warmest year (depending on the dataset) in the 176-year observational record, reflecting the shift to La Niña conditions that temporarily cool the planet. The annually averaged global near-surface temperature was about 1.43 ± 0.13 °C above the 1850–1900 pre-industrial average.
The year 2024 – which started with a strong El Niño - remains the warmest year, at about 1.55 °C above the 1850–1900 average.
Ocean heat content
In 2025, ocean heat content (to a depth of 2,000 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.
The rate of ocean warming over the past two decades, 2005–2025, is more than twice that observed over the period 1960–2005 – and is about 11.0–12.2 Zetajoules per year – about 18 times the annual human energy use per year.
Despite La Niña conditions, around 90% of the ocean surface area experienced at least one marine heatwave in 2025.
Ocean warming has far-reaching consequences, such as degradation of marine ecosystems, biodiversity loss and reduction of the ocean carbon sink. It fuels tropical and subtropical storms and exacerbates ongoing sea-ice loss in the polar regions.
Global mean sea level
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.
The year-to-year increase from 2024 to 2025 was smaller than 2023 to 2024, consistent with short-term variability associated with La Niña conditions.
The rate of global mean sea-level rise since 2012 is higher than the rate of global mean sea-level rise in the earlier part of the satellite record, 1993–2011.
Sea-level rise damages coastal ecosystems and results in groundwater salinization and flooding.
Ocean pH
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.
Ocean pH changes show regional differences. The largest decreases in regional surface pH are observed in the Indian Ocean, the Southern Ocean, the eastern equatorial Pacific Ocean, the northern tropical Pacific and some regions in the Atlantic Ocean.
Ocean acidification harms biodiversity, ecosystems and food production from shellfish aquaculture and fisheries.
Glacier mass balance
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, with eight of the 10 years with the largest glacier ice loss occurring since 2016.
In 2025, exceptional levels of glacier mass loss occurred in Iceland and along the Pacific coast of North America.
Sea-ice extent
The annual average Arctic sea-ice extent for 2025 was the lowest or second lowest on record in the satellite era (1979), and the average Antarctic sea-ice extent for 2025 was the third lowest after 2023 and 2024.
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.
The annual minimum daily extent of Antarctic sea-ice (after the summer melt) tied for the second lowest in the observed record. The past four years have seen the four lowest Antarctic sea ice minima on record.
Extreme Events and Impacts
A supplement to the report provides a snapshot of extreme events, based on inputs from WMO Members, the International Organization for Migration (IOM), Internal Displacement Monitoring Centre (IDMC), United Nations High Commissioner for Refugees (UNHCR), World Food Programme (WFP) and Food and Agriculture Organization of the United Nations (FAO), focusing on the meteorological aspects and the impacts related to displacement and food security.
Extreme weather has cascading impacts on agricultural production. Climate-driven food insecurity is now seen as a risk, with cascading effects on social stability, migration and biosecurity through the spread of plant pests and animal diseases.
It also continues to drive new, onward and protracted displacement of people globally, with particularly severe consequences in fragile and conflict-affected regions. The cascading and compounding impacts of multiple disasters severely limit the ability of vulnerable communities to prepare for, recover from and adapt to shocks.
Climate and heat impacts on health
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, especially among vulnerable populations.
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 and reported case are currently the highest ever recorded.
Heat stress is a growing problem. 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. In addition to health impacts, this leads to productivity and livelihood losses.
As of 2023, only around half of countries provide heat early warning services tailored to the needs of the health sector, and even fewer have fully integrated climate information into health decision-making processes.
There is an urgent need to integrate meteorological and climate data with health information systems to allow decision-makers to move from reactive response towards proactive prevention which saves lives.
Notes to Editors
The State of the Global Climate 2025 report includes scientific contributions from dozens of WMO Members, partners and scientists.
Full details of the datasets, references and institutions involved are available in the report.
The WMO Secretariat wishes to thank everyone who dedicated their time and expertise to this report.
The World Meteorological Organization is the United Nations System’s authoritative voice on Weather, Climate and Water.
For further information, please contact:
- Clare Nullis WMO media officer cnullis@wmo.int +41 79 709 13 97
- Global Communication and Engagement Media Contact media@wmo.int