New Delhi Global temperatures over the past three years (2023-25) averaged more than 1.5 degrees Celsius (C) above pre-industrial levels, marking the first three year period which has exceeded the threshold, Copernicus Climate Change Service (C3S) said on Wednesday.
Last year was the third warmest year on record, only marginally (0.01°C) cooler than 2023, and 0.13°C cooler than 2024 , the warmest year on record, C3S added.
The World Meteorological Organization (WMO) has also confirmed that 2025 was one of the three warmest years on record, continuing the streak of extraordinary global temperatures. The past 11 years have been the 11 warmest on record, it said , adding that ocean temperatures were among the highest last year.
Berkeley Earth, which focuses on land temperature data analysis has warned that the warming spike in 2023 to 2025 appears to have deviated significantly from the previous largely linear trend.
“Since 1970, global warming has proceeded at a roughly linear pace. This roughly linear pace has been consistent in both rate and magnitude with the expected effects of increasing greenhouse gases during this period,” it said. “However, the warming spike in 2023 to 2025 appears to have deviated significantly from the previous trend. If we were to assume that global warming was continuing at the same rate as during the 50-year period 1970-2019, then the 2023 to 2025 excursion would be by far the largest deviation from that trend, with less than a 1-in-100 chance of occurring solely due to natural variability,” Berkeley Earth said on Wednesday.
The Berkeley Earth analysis has indicated that changes in low cloud cover and reductions in man-made aerosol pollution may be responsible for additional recent warming.
In 2025, air temperature over global land areas was second warmest, whilst the Antarctic saw its warmest annual temperatures on record and the Arctic its second warmest, C3S said.
The last three years were exceptionally warm for two main reasons, scientists said. “The first is the build-up of greenhouse gases in the atmosphere, from continued emissions and reduced uptake of carbon dioxide (CO2) by natural sinks. Secondly, sea-surface temperatures reached exceptionally high levels across the ocean, associated with an El Nino event and other ocean variability factors, amplified by climate change. Additional factors include changes in the amounts of aerosols and low cloud and variations in atmospheric circulation,” C3S said.
“Exceeding a three-year average of 1.5°C above pre-industrial levels is a milestone none of us wished to reach, yet it reinforces the importance of Europe’s leadership in climate monitoring to inform both mitigation and adaptation. We expect Copernicus to play an important role in implementing tailored new tools for European climate resilience and risk management,” Mauro Facchini, Head of Earth Observation at the Directorate General for Defence Industry and Space, European Commission said in a statement.
WMO flagged that a separate study published in Advances in Atmospheric Sciences found that ocean temperatures were also among the highest on record in 2025, reflecting the long-term accumulation of heat within the climate system.
About 90% of excess heat from global warming is stored in the ocean, making ocean heat a critical indicator of climate change.
“The year 2025 started and ended with a cooling La Nina and yet it was still one of the warmest years on record globally because of the accumulation of heat-trapping greenhouse gases in our atmosphere. High land and ocean temperatures helped fuel extreme weather – heatwaves, heavy rainfall and intense tropical cyclones, underlining the vital need for early warning systems,” said WMO secretary-general Celeste Saulo in a statement.
The warming spike observed in 2023 to 2025 has been extreme and suggests an acceleration in the rate of Earth’s warming. The spike has multiple causes, including both natural variability and man-made global warming from the accumulation of greenhouse gases, Berkeley Earth said.
HT reported on January 3 that El Nino conditions may emerge in July-August-September this year, early forecasts suggest. This rapid warming spell comes at a time when geopolitical disruptions are expected to impact climate action globally. On January 9, the US withdrew from 66 international organizations and conventions, with its most significant exit, from the United Nations Framework Convention on Climate Change (UNFCCC), likely to deal a crippling blow to global efforts to tackle the climate crisis.
In reference to US exit, climate scientist, Roxy Mathew Koll said: “Global warming does not pause politics. The practical path forward is to keep the institutions working, keep the data flowing, and protect the core functions that the world relies on, including scientific assessment, early warning systems, and climate finance.”
“The White House memorandum signals a broader risk as well. Dependence on any single country for the health of global institutions is fragile and unsustainable. The immediate priority should be to prevent a domino effect. Leaders should publicly reaffirm climate action, protect funding for technical work, and keep COP and IPCC timelines on track. The Intergovernmental Panel on Climate Change (IPCC) is a government body with 195 member countries, including the United States, so its work does not depend on one country – though leadership, continuity, and predictable support still matter to the climate community,” he added.