Human activity has played a significant role in making 2025 the third-hottest year on record, according to experts. Last year's temperatures were notably influenced by mounting fossil fuel pollution, marking a continuation of a three-year streak of "extraordinary global temperatures" as reported by the World Meteorological Organization (WMO).
The WMO's consolidated analysis revealed that 2025 was 1.44C hotter than the preindustrial period, when the large-scale destruction of nature and burning of coal, oil, and gas began. This is despite the Paris Agreement's goal of limiting global warming to 1.5C over a 30-year period. Current trends indicate that this limit could be breached before the end of the decade, more than a decade sooner than initially anticipated when the agreement was signed in 2015.
Carlo Buontempo, the director of the Copernicus climate change service, emphasized that the 1.5C limit is likely to be exceeded. He highlighted the challenge of managing the inevitable overshoot and its consequences. The eight datasets analyzed, based on billions of weather measurements, consistently ranked 2025 as the third-hottest year on record, with some datasets placing it as the second-hottest.
The year 2024, plagued by heatwaves and wildfires, holds the title of the hottest year on record since the mid-19th century. Tim Osborn, from the University of East Anglia's climate research unit, attributed the recent temperature surge to a natural weather pattern in the Pacific known as El Niño, which contributed approximately 0.1C to global temperatures in 2023 and 2024. By 2025, this natural influence had weakened, providing a clearer picture of the underlying warming trend.
Copernicus data revealed that the first month of 2025 was the hottest January on record, with March, April, and May each being the second-warmest for their respective times of year. Every month except February and December was warmer than any corresponding month before 2023. This unnatural heat is largely attributed to a blanket of carbon pollution, exacerbating weather extremes and disrupting the stable conditions necessary for human prosperity.
While temperatures over the tropical Atlantic and Indian Ocean were less extreme in 2025 compared to 2024, these were partly offset by higher temperatures at the poles. Antarctica recorded its hottest year, and the Arctic its second-hottest. Polar sea ice cover reached its lowest level since satellite observations began in the 1970s in February. Throughout the year, half of the planet's land experienced more days than average with at least "strong" heat stress, when temperatures feel above 32C.
Berkeley Earth, a US non-profit that also analyzed the temperatures, estimated that 8.5% of the world's population lives in areas that experienced record-high annual average temperatures last year. Their scientists predict similar heat in 2026. Bill McGuire, an emeritus professor of climate hazards at University College London, described the findings as "grim but far from unexpected." He emphasized that the 1.5C limit is now at risk, and dangerous climate breakdown has arrived, despite a boom in renewable energy and regional successes in cleaning up economies. The data clearly indicates that human activity remains the dominant driver of exceptional temperatures, and the atmosphere is sending a message that we must heed.
