Every person alive today has grown up amid worsening weather extremes. A World Meteorological Organization (WMO) report says the Earth’s climate is more out of balance than at any point in observed history, with consequences likely to reverberate for centuries or millennia.
Key findings from the WMO State of the Global Climate 2025 report:
– 2015–2025 was the hottest decade on record.
– Oceans registered unprecedented heat for the ninth consecutive year.
– Glaciers and sea ice continue to retreat.
– Extreme weather, cascading health risks and rising human costs intensified.
– Earth’s energy imbalance reached an all-time high — more solar energy is entering the system than is leaving.
– Global mean sea level has been rising faster since 2012 than in the two prior decades.
UN Secretary-General António Guterres warned that “every key climate indicator is flashing red,” noting humanity has endured the 11 hottest years on record and urging rapid action.
Temperature and greenhouse gases
Depending on the dataset, 2025 ranked second or third hottest, about 1.43°C above pre‑industrial levels, slightly below 2024’s 1.55°C due in part to a temporary La Niña cooling influence. The principal driver remains rising greenhouse gas concentrations from burning oil, coal and gas. Atmospheric CO2 reached its highest level in at least two million years in 2024 and continued rising in 2025.
Scientists flag the risk that El Niño could return later in 2026, potentially pushing temperatures higher and fueling more extremes.
Impacts: heat, disasters, health and displacement
In 2025 heatwaves, wildfires, floods, droughts and tropical cyclones caused thousands of deaths and billions in economic losses. California wildfires in January 2025 alone generated over $60 billion in damages, the costliest such event on record.
The report highlights growing health impacts: dengue fever is spreading as the fastest-growing mosquito-borne disease, and about 1.2 billion workers are exposed each year to dangerous heat. Climate change is also driving hunger, migration and water scarcity; weather-related disasters have displaced roughly 250 million people over the past decade. The UN links the climate crisis to global instability and notes that conflict and military activity also contribute significant emissions.
Earth’s energy imbalance and lasting warming
For the first time the WMO included Earth’s energy imbalance — the difference between incoming solar radiation and heat escaping to space — as an indicator. That imbalance reached a record high in 2025. Greenhouse gases act like a blanket, trapping heat: roughly 91% of the excess energy is absorbed by oceans, 5% by land, 3% by ice and glaciers, and 1% heats the atmosphere. WMO Secretary‑General Celeste Saulo warned that human activities are disrupting the planet’s equilibrium and that impacts will persist for hundreds to thousands of years.
Oceans and cryosphere
Oceans, the main planetary heat sink, broke heat records again. Around 90% of the ocean surface experienced at least one marine heatwave in 2025. Warming is increasing throughout ocean depths; these changes are effectively irreversible on centennial to millennial timescales, meaning significant emissions cuts today would not halt ocean warming this century because of the existing energy imbalance.
Warmer seas are bleaching coral, shrinking fish populations, weakening the ocean’s ability to absorb CO2, fueling more powerful storms, and accelerating polar ice loss — all contributing to sea level rise that threatens coastal cities. Arctic and Antarctic sea ice were among their lowest levels on record, and glacier mass loss ranked among the five worst years since 1979. Glaciers are crucial freshwater sources for about two billion people.
Policy and preparedness
The WMO report does not prescribe policy, but its findings are intended to inform governments and organizations so they can prepare and adapt to intensifying climate risks. Integrating weather and climate data into health and disaster systems could enable more proactive responses to protect lives. As Celeste Saulo put it: “When we observe today, we don’t just predict the weather, we protect tomorrow.” Edited by Tamsin Walker
