French President Emmanuel Macron warned Wednesday that France faced "sacrifices" in a new era marked by climate change and instability caused by Russia's invasion of Ukraine that signalled "the end of abundance".

After a summer of drought, massive wildfires and continuing loss of life in Ukraine, the 44-year-old leader delivered a stark speech at the start of the first cabinet meeting after the country's traditional August holiday break.

"I believe that we are in the process of living through a tipping point or great upheaval. Firstly because we are living through... the end of what could seem like the end of abundance," he said.

The speech appeared designed to prepare the country for what promises to be a difficult winter ahead, with energy prices rising sharply and many families struggling with inflation.

Ahead of the six-month anniversary of Moscow's invasion of its neighbour, Macron had vowed on Tuesday that European support for Ukraine would continue "for the long term" despite the cost and impact on incomes.

"Our system based on freedom in which we have become used to living, sometimes when we need to defend it, it can entail making sacrifices," Macron told ministers on Wednesday, reprising comments he made on August 19 during his holiday.

Macron had called on French people to "accept paying the price of liberty" during an address in the south of France.

In his speech Wednesday, he also referred to the severe drought over the summer in France, which has prompted water restrictions across most of the country and increased fears about the pace of climate change.

"This overview that I'm giving -- the end of abundance, the end of insouciance, the end of assumptions -- it's ultimately a tipping point that we are going through that can lead our citizens to feel a lot of anxiety," Macron continued.

"Faced with this, we have duties, the first of which is to speak frankly and very clearly without doom-mongering," he said.

Macron was re-elected to a second term in April but lost his parliamentary majority in elections in June, meaning Prime Minister Elisabeth Borne heads a minority government that depends on opposition parties to pass legislation.

French inflation was clocked at 6.1 percent last month, one of the lowest rates in Europe thanks to government price caps on electricity and gas, as well as tax cuts on petrol and diesel.

But trade unions are pushing for major wage increases and have called for a day of strikes and rallies on September 29.

The head of the hard-left CGT union, Philippe Martinez, told BFM television that the president's speech was "inappropriate", adding that the poorest were already paying the price of the war and that further sacrifices could not be expected.

"He'll ask for them (sacrifices) and we will oppose them," Martinez said.

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