Global temperatures from 2023-2025 exceeded 1.5°C threshold for 1st time: Report

Global temperatures from the past three years (2023-25) averaged over 1.5°C above pre-industrial levels, marking the first three-year period that has exceeded the threshold, European Union’s 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.

But, in 2025, air temperature over global land areas was the second warmest, whilst the Antarctic saw its warmest annual temperatures on record and the Arctic its second warmest, C3S said.

The last three years, 2023-2025, 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 Niño 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.

Mauro Facchini, Head of Earth Observation at the Directorate General for Defence Industry and Space, European Commission, said exceeding a three-year average of 1.5°C above pre-industrial levels is a milestone none of them 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,” said Facchini in a statement.

In 2025, air and sea surface temperatures in the tropics were lower than in 2023 and 2024, yet still much above average in many areas outside of the tropics, the C3S said. The lower tropical temperatures compared to 2023-2024 were due to ENSO-neutral or weak La Niña conditions in the equatorial Pacific throughout 2025.

HT reported on January 3 that El Niño conditions may emerge in July, August, and September this year. Geopolitical disruption could also impact climate action globally.

The US this month withdrew from 66 international organisations 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 the US exit, climate scientist Roxy Mathew Koll had said: “Global warming does not pause for 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.