The European Union's Copernicus Climate Change Service releases monthly and annual reports on the state of the climate, which partly rely on data from US government agencies.

Its latest Global Climate Highlights report, published Wednesday, concluded that 2025 was the third hottest year on record after all-time highs in 2023 and 2024.

Copernicus uses billions of satellite and weather observations from land and at sea, including from US agencies, with records dating back many decades.

"The US is still a reliable supplier of data for forecasts," Florian Pappenberger, the director general of the European Centre for Medium-Range Weather Forecasts (ECMWF), which operates Copernicus, told AFP.

"At the moment we have seen ... no operational impact" from the announced cuts, he said.

Pappenberger, however, voiced concern about the potential loss of any data in the future.

"Losing observations is a worrying thing for any weather forecaster because the availability and the quantity of observations is directly linked to the quality of weather forecasts," he said.

"The worry is that you stop an existing observation system and therefore don't have the data for a future exercise of creating these types of reports."

Trump has pursued deep cuts to federal climate science and Earth-observation funding, including programs that contribute data to international monitoring networks.

US lawmakers have drafted 2026 spending bills that would reject Trump's cuts to NASA and the National Oceanic and Atmospheric Administration (NOAA), but the legislation has not yet been finalised.

Copernicus director Carlo Buontempo said coordination with NASA and NOAA "has continued all the same" but potential US cuts are "a risk we need to consider".

The United States, for example, is a major financial contributor to an international ocean data program, which consists of robotic floats that drift under water for days and resurface to beam information to satellites.

"If we lose deep ocean observation, this will make us blind for a number of years," Buontempo told AFP.