Human activity helped make 2025 the third warmest year on record, experts say

Based on measured data, scientists state that the 2015 Paris Agreement, which aimed to keep global warming below 1.5°C, is “dead.” Last year was the third warmest on record, according to scientists, with rising pollution from fossil fuels behind the “exceptional” temperatures, the British newspaper The Guardian reports.

The World Meteorological Organization (WMO) said that 2025 continued a three-year streak of “extraordinary global temperatures,” during which the average surface air temperature was 1.48°C above pre-industrial levels.

According to the European Union’s Copernicus Climate Service, the current pace of warming could lead to the 1.5°C limit of the Paris Agreement—calculated as a 30-year average—being exceeded before the end of this decade. That is more than ten years earlier than scientists expected when world leaders signed the agreement in 2015.

“It is inevitable that we will exceed this threshold,” said Carlo Buontempo, director of the Copernicus Climate Service. “The question now is how best to manage this unavoidable overshoot and its consequences.” The eight datasets released on Wednesday are based on billions of meteorological measurements from satellites, ships, aircraft, and weather stations. They were independently compiled by several climate-monitoring organizations in Europe, the United States, Japan, and China, with only minor differences between their results.

A joint analysis by the WMO found that 2025 was 1.44°C warmer than pre-industrial levels, when large-scale destruction of nature and massive burning of coal, oil, and gas began. Six datasets ranked 2025 as the third warmest year on record, while the remaining two ranked it as the second warmest.

The warmest year ever recorded since the mid-19th century remains 2024, which was marked by heatwaves and widespread wildfires. The UK Met Office said that natural climate variability and reductions in aerosol pollutants—which partly mask warming—also contributed to the unusually high temperatures in recent years.

Tim Osborn, director of the Climatic Research Unit at the University of East Anglia, which contributed to the data analysis alongside the Met Office, said that the El Niño weather phenomenon in the Pacific Ocean raised global temperatures in 2023 and 2024 by about 0.1°C, contributing to the “sudden onset of the recent temperature spike.”

Streets in Florence during the heatwave in September 2025

“This natural influence had weakened by 2025,” he said. “And therefore the global temperature recorded in 2025 gives us a clearer picture of the underlying warming trend.”

According to Copernicus, January 2025 was the warmest January on record, while March, April, and May were each the second warmest months for their respective periods. Scientists found that every month except February and December was warmer than the corresponding month in any year before 2023.

The poles are being exposed

The unnatural heat is largely the result of a layer of carbon pollution covering the Earth, which worsens most extreme weather events and threatens the stable conditions in which humanity has thrived. Copernicus found that temperatures over the tropical Atlantic and Indian Oceans in 2025 were less extreme than in 2024, but this was partly offset by higher temperatures at the poles. Antarctica recorded its warmest year ever, and the Arctic its second warmest.

Sea ice coverage at the poles fell in February to its lowest level since satellite observations began in the 1970s. Over the course of the year, half of the planet’s land area experienced more days than average with at least “strong” heat stress, when temperatures feel above 32°C.

Berkeley Earth, a US non-profit organization that also analyzed temperatures, estimates that 8.5% of the global population lives in areas that recorded all-time high average annual temperatures last year. Its scientists said that similar heat is likely in 2026 as well.

More and more people will be forced to leave their homes because of the climate

A message from the atmosphere

Bill McGuire, emeritus professor of climate hazards at University College London, who was not involved in the analysis, described the findings as “bleak, but far from unexpected.”

“Under all circumstances, the 1.5°C limit is now dead,” he said. “Whichever way you look at it, dangerous climate breakdown has arrived, with little sign that the world is prepared or taking it seriously.”

Global emissions continue to rise even a decade after the Paris Agreement was signed, despite a boom in renewable energy and regional successes in cleaning up polluted economies. Laurence Rouil, director of the Copernicus Atmosphere Monitoring Service, said that the 2025 data provide a clear picture that human activity remains the main driver of exceptional temperatures.

“The atmosphere is sending us a message,” she said. “And we must listen.”

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