Air travel between Paris and regional hubs such as Nantes, Lyon and Bordeaux will now be banned.

The change, which came into effect on Tuesday, will mostly rule out air trips between Paris and regional hubs such as Nantes, Lyon and Bordeaux, with connecting flights unaffected.

Max Boycoff, chairman of environmental studies at the University of Colorado, Boulder, said the French law will be a test case for governments around the world.

“While this material impact is quite minimal – only 2 percent of global emissions come from aviation – in symbolic ways, it has a lot of purchase,” he told Al Jazeera. “The way in which this generates conversations, much like the one we’re having now, can open up further possibilities for emissions cuts elsewhere.”

He noted rail travel represents about one-third of the hydrocarbon emissions compared with flights.

“Everything does count and the ways we get from place to place does matter, and transportation overall contributes to somewhere between one-quarter and 30 percent of global emissions. This demonstrates the power of climate policy action,” Boycoff said.

Although the measure was included in a 2021 climate law and already applied in practice, some airlines had asked the European Commission to investigate whether it was legal.

The law specifies train services on the same route must be frequent, timely and well-connected to meet the needs of passengers who would otherwise travel by air – and able to absorb the increase in passenger numbers.

Laurent Donceel, interim head of industry group Airlines for Europe (A4E), said governments should support “real and significant solutions” to airline emissions, rather than “symbolic bans”.

A4E highlighted its own net zero by 2050 strategy, which includes switching from jet fuel to non-fossil sources and deploying battery or hydrogen-powered aircraft.

The step comes as French politicians have also debated how to reduce emissions from private jets.