The United Nations has raised alarm over unprecedented levels of heat retained by the Earth in 2025, cautioning that the effects of this warming could persist for thousands of years.
This warning comes as the organization confirmed that the past decade has been marked by consistently extreme temperatures.
According to the World Meteorological Organization (WMO), the 11 hottest years ever recorded all occurred between 2015 and 2025, as detailed in its annual State of the Global Climate report. The agency noted that 2025 ranked among the second or third warmest years on record, with global temperatures approximately 1.43 degrees Celsius above the 1850–1900 baseline.
“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 U.N. 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.”
For the first time, the WMO report assessed the Earth’s energy imbalance — the difference between incoming solar radiation and outgoing energy. Under normal conditions, these forces remain in equilibrium. However, the agency explained that rising concentrations of greenhouse gases such as carbon dioxide, methane, and nitrous oxide — now at their highest levels in at least 800,000 years — have disrupted this balance.
“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.”
WMO Secretary-General Celeste Saulo highlighted that recent scientific progress has deepened understanding of this imbalance and its long-term implications.
“Human activities are increasingly disrupting the natural equilibrium and we will live with these consequences for hundreds and thousands of years,” she said.
The report found that over 91 percent of excess heat is absorbed by the oceans, which are now experiencing record levels of warming.
“Ocean heat content reached a new record high in 2025 and its rate of warming more than doubled from 1960-2005 to 2005-2025,” the WMO said.
Scientists warned that rising ocean temperatures are already driving widespread impacts, including damage to marine ecosystems, biodiversity loss, and reduced capacity of oceans to absorb carbon.
“It fuels tropical and subtropical storms and exacerbates ongoing sea-ice loss in the polar regions.”
Both the Antarctic and Greenland ice sheets continue to lose mass, while Arctic sea ice coverage in 2025 reached one of its lowest levels since satellite records began. Meanwhile, global sea levels have risen by about 11 centimetres since 1993, with projections indicating continued increases for centuries.
Describing the broader outlook, WMO scientific officer John Kennedy noted that global weather patterns are still being influenced by La Nina, a natural cooling phenomenon in the Pacific Ocean that alters winds, pressure, and rainfall. These conditions alternate with the warming El Nino cycle.
Kennedy explained that while 2024 — the warmest year on record at approximately 1.55 degrees Celsius above pre-industrial levels — coincided with a strong El Nino, forecasts suggest neutral conditions by mid-2026, with a possible return of El Nino before the year ends.
“If so, “then we’re likely to see maybe elevated temperatures again in 2027″,” he told a press conference.
WMO Deputy Secretary-General Ko Barrett described the findings as deeply concerning. She emphasized that the organization aims to provide clear scientific evidence to motivate action but acknowledged the grim trajectory.
She said the outlook was a “dire picture”.
She said the WMO provided the evidence it sees, hoping that the information “will encourage people to take action”.
But there was “no denying” that “these indicators are not moving in a direction that provides for a lot of hope”, she said.
Amid ongoing global tensions and rising fuel costs, Guterres urged leaders to take the climate crisis seriously, linking fossil fuel dependence to both environmental and geopolitical instability.
“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,” he said.
“Today’s report should come with a warning label: climate chaos is accelerating and delay is deadly,” he said.
