The Earth is being pushed toward the limits of its thermal capacity as its energy imbalance—the difference between the energy entering the system and the energy radiated back into space—keeps growing. Since systematic measurements began in 1960, and especially over the last two decades, this imbalance has risen steadily and reached a new record high in 2025. Almost all of that extra energy is being stored in the oceans, posing a serious threat to ecosystems, food security and human health.
According to the State of the Global Climate report from the World Meteorological Organization (WMO), the period 2015–2025 was the warmest decade in recorded history and 2025 ranked as the second or third warmest year ever, with a global average temperature of about 1.43 ºC above the 1850–1900 baseline, depending on the dataset. In comparison, 2024 remains the record‑holder year, at roughly 1.55 ºC above pre‑industrial levels.
Oceans as the planet’s “heat sink”
The report stresses that Earth’s climate system is more out of balance than at any previous time in the observational record. Rising concentrations of greenhouse gases—especially carbon dioxide, methane and nitrous oxide—drive the continuous warming of both the atmosphere and the oceans, as well as the melting of ice.
The WMO analysis also details where the planet’s excess heat is going:
- More than 91% is absorbed by the oceans.
- Only about 1% stays in the atmosphere.
- Around 5% warms land masses.
- An additional 3% goes into melting ice.
In 2025, ocean heat content reached a new record, and the rate of warming has more than doubled between the periods 1960–2005 and 2005–2025. For the past nine years in a row, a new record heat content has been recorded for the oceans.
About 90% of the ocean surface experienced at least one marine heatwave in 2025, severely stressing marine life and accelerating coral bleaching, including in places like the Raja Ampat islands in Papua, as documented by environmental groups and observers.
Ice, sea level and extreme weather
The warming of the oceans feeds into the loss of ice and rising seas. In 2025, the annual average extent of Arctic sea ice hit a record low or close to it, while Antarctic sea ice ranked as the third‑lowest on record. Glacial melt continued unabated, further contributing to global sea‑level rise.
Over the past three decades, the global mean sea level has risen about 11 centimeters above the 1993 satellite baseline, and the pace has accelerated. According to the latest projections from the Intergovernmental Panel on Climate Change (IPCC), ocean warming and sea‑level rise will continue for centuries, and many of these changes are effectively irreversible on timescales of centuries to millennia.
Extreme events connected to this warming—extreme heatwaves, droughts, wildfires, tropical cyclones, storms and floods—caused thousands of deaths, displaced millions of people and inflicted multi‑billion‑dollar economic losses around the world in 2025 alone. The WMO warns that these patterns are no longer anomalies: they are the new norm.
Energy imbalance and “red flag” diagnostics
For the first time, the WMO report explicitly includes Earth’s energy imbalance as a key climate indicator. In a stable climate, incoming solar energy roughly equals outgoing thermal radiation. Human activities, especially the burning of fossil fuels, are now distorting that balance, trapping more heat and forcing the planet into a warmer, less predictable state.
“Human activities are increasingly altering the planet’s natural balance and we will live with these consequences for hundreds and thousands of years,” says WMO Secretary‑General Celeste Saulo.
A call to action from the UN chief
UN Secretary‑General António Guterres framed the findings bluntly: “Humanity has just experienced the eleven warmest years in history. When a pattern repeats itself eleven times, it is no longer a coincidence. It is a call to action.”
For Guterres, the climate crisis does not only threaten environmental stability; it also undermines global security and geopolitical stability. “In an era of war,” he said, “climate stress reveals another truth: our dependence on fossil fuels destabilizes not only the climate but also global security.”
Guterres concluded: “The chaos of climate change is accelerating, and delay in action is fatal.” The WMO report, in his view, should be read as a clear warning label: the planet’s heat engine is running hotter, and the only way to avoid the worst consequences is to drastically reduce greenhouse gas emissions—fast.
