The estimated reduction of less than one percent extends a slowdown seen in recent years, said Citepa, a non-profit organisation tasked by France's ecology ministry with tallying the country's greenhouse gas inventory.

France, a major economy seen as a leader in transitioning to a low-carbon future, slashed its output of planet-heating emissions by 6.8 percent in 2023.

But the rate of decline slowed sharply to 1.8 percent in 2024 and is tipped to slip even further in 2025 to just 0.8 percent, said Citepa's latest progress report for the ministry.

"This slight decrease in greenhouse gas emissions would confirm the slowdown in momentum observed in recent years," it said.

France's current emissions reduction target for 2030 is at least 40 percent compared to 1990 levels, but a plan under development proposes raising this goal to 50 percent.

To achieve this, France needs to cut emissions by around five percent each year between 2022 and 2030 -- well above the current pace.

France is far from alone in Europe, with Germany and Britain also struggling to sustain the momentum after posting impressive cuts in recent years.

Major polluters elsewhere are also stalling.

The United States only managed a 0.2 percent reduction in 2024, even before President Donald Trump took office promising to unwind climate protections and drill for more oil and gas.

- Nations under pressure -

Cipeta said France's first quarter emissions for 2025 actually rose slightly, due in part to higher gas and electricity use for heating school and residential buildings.

The sharp drops in energy emissions seen over the past two years were forecast to slow considerably in 2025, it added.

"The use of nuclear power should stabilise in the second half of 2025, remaining at a historically high level," Cipeta said.

"In addition, as the use of fossil fuels is already very low, it should stabilise without allowing the gains observed in the past."

The slowdown comes as nations face pressure to commit new climate targets in line with international efforts to keep global warming to 1.5 degrees Celsius above preindustrial levels.

On Wednesday, the 27-nation European Union unveiled its long-delayed goal of cutting emissions by 90 percent by 2040 compared to 1990 levels -- but with contested new flexibilities built in.

EU emissions fell by 8.3 percent in 2023 compared to 2022, and are now 37 percent below 1990 levels.