A court in Paris ruled on Wednesday that France failed to take sufficient action to tackle climate change in a case brought by four NGOs.
The decision is a blow to French President Emmanuel Macron, who has been vocal in his support for climate change action.
In December, he pushed to strengthen the EU’s 2030 targets to reduce greenhouse gases by at least 55 per cent compared with 1990 levels, up from the previously agreed goal of 40 per cent.
The Paris administrative court, which handles cases involving the state, held the government responsible for failing to fully meet its goals in reducing greenhouse gases.
Paris said it “took note” of the decision, and provided a list of actions in the pipeline to “allow France to respect in the future the objectives it set”.
"The government remains fully engaged to take up the climate challenge and leave no one on the side of the road in this indispensable transition," said the statement, which was signed by Barbara Pompili, Minister for Ecological Transition.
France is missing its national targets set under the 2015 Paris Agreement to curb climate change, and the country has put most of its efforts on hold.
The court ruled there was a link between ecological damage and deficiencies by the state in respecting its own goals.
It decided that awarding money was not appropriate in this case. Instead, the court said, reparations should centre on fixing the failures identified.
The court gave the French government two months in which to find measures to address the problem.
The case was brought by Greenpeace France, Oxfam France, the Nicolas Hulot Foundation and Notre Affaire a Tous.
They said Mr Macron’s lobbying for global climate action was not backed up by sufficient domestic measures to curb emissions blamed for global warming.
The NGOs said it was a “victory for truth” and that until now France has denied the “insufficiency of its climate policies”.
Greenpeace France chief Jean-Francois Julliard said the decision "shows the state has a special responsibility in the climate fight."
“Emmanuel Macron, more than other heads of state, spoke out strongly on the subject. Today, he cannot remain silent,” Mr Juillard said.
The decision “goes beyond French borders,” he said, because it can help those fighting such battles in other countries.
Cecile Duflot, head of Oxfam France, said the decision was good news “for children born today who will live through catastrophic weather reports”.
“It is the first big climate trial [in France] and it has been won,” she said.
More than 2.3 million people signed a petition to support the court action.
Earlier on Wednesday, the EU’s top court ruled that Hungary had “systematically and persistently” breached legal limits on air pollution from particulate matter, in some regions for as long as 12 years.