The amount of heat being trapped by the Earth reached a record high in 2025, according to the United Nations, with scientists warning that the effects of this imbalance could shape the planet for thousands of years to come.
In its latest State of the Global Climate report published on Monday, the World Meteorological Organization confirmed that the past decade has been unprecedented. The 11 hottest years ever recorded have all occurred between 2015 and 2025 – a pattern that leaves little room for doubt about the trajectory of global warming.
Last year ranked among the two or three warmest on record, with global temperatures sitting around 1.43C above the 1850–1900 baseline. While the figure may sound incremental, scientists stress that even small increases at this scale translate into profound shifts across the Earth system.
UN Secretary-General Antonio Guterres struck an urgent but purposeful tone, describing the climate as being in a state of emergency. Yet he also framed the moment as a clear signal for action rather than resignation, noting that repeated records are not coincidence but a call to respond.
A key addition to this year’s report is a closer look at the Earth’s energy imbalance – essentially the difference between energy entering the planet from the Sun and energy leaving it. In a stable climate, these flows are roughly equal. Today, they are not.
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 tipped that balance. The result is a growing surplus of heat within the Earth system, which reached a new peak in 2025.
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Ocean heat and rising seas
One of the most striking findings is where that excess heat is going. More than 91 percent of it is being absorbed by the oceans, making them central to understanding both the problem and its long-term consequences.
Ocean heat content hit another record in 2025, with the rate of warming more than doubling when comparing the periods 1960–2005 and 2005–2025. This acceleration is reshaping marine environments, contributing to biodiversity loss and weakening the ocean’s ability to absorb carbon.
Warmer seas also provide more energy for storms, intensifying tropical and subtropical systems, while accelerating the loss of sea ice in polar regions. Both Antarctica and Greenland are continuing to lose ice mass, and Arctic sea ice extent last year was among the lowest ever recorded.
Sea levels are rising in step. Global mean sea level is now about 11 centimetres higher than in 1993, when satellite measurements began. Even if emissions were stabilised, scientists say ocean warming and sea level rise would continue for centuries – a reminder of how deeply embedded these changes have become.
Despite the scale of the challenge, improved scientific understanding is offering clearer insights than ever before. WMO chief Celeste Saulo emphasised that advances in monitoring and modelling are helping to sharpen the picture, giving policymakers better tools to act decisively.
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Shifting climate outlook
Natural climate patterns continue to play a role in shaping year-to-year variations. The planet is currently under the influence of La Nina, a cooling phase in the Pacific that affects global weather patterns. It typically alternates with the warming El Nino phase, with neutral conditions in between.
The record warmth of 2024, which reached around 1.55C above pre-industrial levels, coincided with a strong El Nino. Looking ahead, forecasters expect a return to neutral conditions by mid-2026, with a possible El Nino developing later in the year – a shift that could push temperatures higher again in 2027.
WMO officials acknowledge that the overall outlook presents serious challenges. Yet the purpose of the report is not only to document trends but to inform action. By laying out the evidence clearly, they hope to galvanise governments, businesses and communities to accelerate the transition away from fossil fuels.
Guterres underlined that climate change is not happening in isolation. In a world already grappling with geopolitical tensions and energy pressures, reliance on fossil fuels is proving to be both an environmental and a security risk.
(with newswires)
