WORLD: Earth’s climate more unbalanced than ever, WMO warns

A melting glacier in Iceland, which experienced exceptional retreat in 2025 – Image: Michael Piepgras/CHROMORANGE/picture alliance

Climate change: The world’s oceans have broken heat records for nine straight years, glaciers are retreating and extreme weather is killing thousands. The only way to avoid the worst is to urgently ditch fossil fuels.

Every person alive today has grown up in a world of worsening weather extremes. Last year, a 50-year flood swamped Texas, glaciers in Iceland melted at record speed, a hurricane struck Jamaica with near-unprecedented force, and the world sweltered through record heat. The window to change course is narrowing fast, warn scientists.

A report published Monday by the World Meteorological Organization (WMO) confirms the Earth’s climate is more out of balance than at any point in observed history — and that the consequences will reverberate for centuries, and potentially millennia.

Key findings in the annual WMO State of the Global Climate 2025 report include:

• 2015 to 2025 was the hottest decade on record
• Oceans reached unprecedented heat for the ninth year running
• Glaciers and sea ice continue their retreat
• Extreme weather, cascading health risks and mounting human costs
• Earth’s energy imbalance hits an all-time high, which means more of the sun’s energy is entering the planet’s systems than is leaving
• Global mean sea level is rising at a faster rate since 2012 than in the preceding two decades.

“Every key climate indicator is flashing red,” said UN Secretary-General Antonio Guterres. “Humanity has just endured the 11 hottest years on record. When history repeats itself 11 times, it is no longer a coincidence. It is a call to act.”

Burning fossil fuels such as oil, coal and gas, releases heat-trapping greenhouse gases that are warming the Earth and changing its energy balance – Image: Gerald Herbert/AP Photo/picture alliance

Rising heat, extreme weather and global instability

Depending on the data set used, last year ranked second or third hottest on record at approximately 1.43 degrees Celsius (2.57 Fahrenheit) above pre-industrial levels. That was slightly below the 2024 record of 1.55 C. The dip was due to global weather phenomenon La Nina’s temporary cooling influence.

Under the 2015 Paris Agreement, countries agreed to cap warming at 2 C and ideally 1.5 C to avoid the worst impacts of planetary heating.

The key driver of rising temperatures is surging greenhouse gas concentrations in the atmosphere, largely caused by burning oil, coal, and gas. Carbon dioxide (CO2) reached its highest atmospheric level in at least 2 million years in 2024, and continued rising in 2025, according to the report.

The findings carry particular urgency for the year ahead. The warming weather pattern El Nino could return later this year, which scientists say could drive another sharp temperature increase, fueling more extreme weather.

In 2025, heatwaves, wildfires, flooding, drought and tropical cyclones caused thousands of deaths and billions in economic losses. The California wildfires in January 2025 alone caused more than $60 billion (€52.4 billion) in damage and were the costliest such event ever recorded.

The report underlined climate change’s growing health toll, including dengue fever — now the world’s fastest-growing mosquito-borne disease. Meanwhile, 1.2 billion workers, over a third of the global workforce, are exposed to dangerous heat each year.

Climate change is also driving hunger, migration and water scarcity, increasing competition over dwindling resources. Over the past decade, weather-related disasters have forced 250 million people to leave their homes.

The UN has drawn a direct line between the climate crisis and global instability. At the same time, war and militaries themselves are a significant contributor to planet-warming emissions.

“Our addiction to fossil fuels is destabilizing both the climate and global security,” UN Secretary-General Antonio Guterres said in a statement.

Guterres added that countries have to act quickly to decarbonize to stop further warming, and accelerate a transition to renewable energy. “Renewables deliver climate security, energy security and national security,” he said.

Hurricane Melissa was one of the strongest to ever hit the Caribbean and was made six times more likely by climate change, as a warming planet supercharges storms – Image: RICARDO MAKYN/AFP/Getty Images

So Earth’s energy is out of whack: What does that actually mean?

Appearing for the first time as an indicator in the WMO report, Earth’s energy imbalance — the gap between solar energy entering the atmosphere and heat escaping back into space — reached a record high in 2025. In a stable climate, the sun’s incoming and outgoing energy are the same.

In today’s climate, much more energy is coming in than is leaving because greenhouse gases act like a blanket around the planet, trapping excess heat across its systems. Around 91% is absorbed by oceans, 5% by land, 3% by ice sheets and glaciers, and 1% heats the atmosphere.

“Human activities are increasingly disrupting the natural equilibrium, and we will live with these consequences for hundreds and thousands of years,” said WMO Secretary-General Celeste Saulo.

Accelerated warming: The consequences for the oceans

The oceans are the planet’s main heat energy sink — and protect life on Earth from the worst impacts of climate change. But ocean heat broke records again in 2025 for the ninth consecutive year, with 90% of the ocean surface experiencing at least one marine heatwave, despite cooling La Nina.

The report’s authors said there was no sign of that heat sink weakening, but they said warming was increasing across all ocean layers, including the deep sea. Changes to ocean temperature are now irreversible on timescales of centuries to millennia. Even significant emissions reductions today would not halt ocean warming this century due to the energy imbalance in the Earth system, said the report.

Homes perched on Australia’s eastern coastal town of Wamberal that are at risk of being swept away following storm surges – Image: Peter Parks/AFP

The human cost of ocean warming is vast. Some 3 billion people rely on seafood for protein, yet rising temperatures are bleaching coral, shrinking fish populations and weakening the ocean’s ability to absorb CO2. Warmer seas are also fueling more powerful storms and accelerating ice loss at both poles, driving sea-level rise, with cities and coastal areas on the frontline.

Arctic and Antarctic sea ice were among the lowest levels on record, while glacier mass loss ranked in the five worst years since records began in 1979. Glaciers are crucial for supplying water to two billion people.

The WMO report doesn’t make any policy recommendations. But it says its findings should help governments and organizations prepare for and adapt to intensifying extreme weather linked to climate change. For example, weather and climate data could be plugged into health information systems to enable a more proactive response that could help save lives.

“When we observe today, we don’t just predict the weather, we protect tomorrow. Tomorrow’s people. Tomorrow’s planet,” said WMO’s Celeste Saulo.

DW.com/NAN 24-3-26

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