As pale morning light flickered across the Seine, Capt. Freddy Badar steered his hulking river barge, Le Bosphore, past picturesque Normandy villages and snow-fringed woodlands, setting a course for Paris.

Onboard were containers packed with furniture, electronics and clothing loaded the night before from a cargo ship that had docked in Le Havre, the seaport in northern France. Had the cargo continued by road, 120 trucks would have clogged the highways. Using Le Bosphore and its crew of four prevented tons of carbon emissions from entering the atmosphere.

“The river is part of a wider solution for cleaner transport and the environment,” Captain Badar said, his eyes scanning other vessels carrying wares up and down the Seine. “But there’s much more that we could be doing.”

As the European Union steps up its battle against climate change, it needs to decarbonize freight transport, responsible for a quarter of global greenhouse gas emissions.

To get there, it is turning back to a centuries-old solution: its rivers. With 23,000 miles of waterways spanning the European Union, officials see a huge potential to help take trucks — the biggest source of freight emissions — off roads. The European Green Deal, the European Union’s decarbonization blueprint, would turn rivers into highways and double barge traffic by 2050.

There’s a lot of room for improvement. Today, rivers carry less than 2 percent of Europe’s freight. By comparison, around 6.5 million trucks crisscross Europe’s roads, accounting for 80 percent of freight transport. Rail accounts for around 5 percent.

If rivers are to handle more traffic, much of Europe’s decades-old waterway infrastructure, including ports and locks, will need upgrading. A warming planet adds to the challenge: Droughts in recent years have grounded some transport on the Rhine, and pose risks to the Seine.

While the Seine isn’t the most heavily trafficked river in Europe — that is the Rhine, which flows through Germany and the Netherlands — the ambition is to turn it into one of the main experimental hubs for the climate transition.

“We are working on a transformation to get businesses to massively shift their logistics routes,” said Stéphane Raison, the president of France’s main port operator, Haropa, which is investing over 1 billion euros (or $1.1 billion) in the Seine effort.

Turning Toward the River

Before leaving Le Havre for Paris, as a heavy snow fell in the dark, Le Bosphore’s crew packed containers tightly into the cargo hold, checking a manifest as a gantry crane swung overhead.

Le Bosphore, part of a 110-barge fleet run by Sogestran, France’s largest river transport company, will head to Gennevilliers, a port five miles outside Paris that is a distribution hub for the capital region’s 12 million consumers. The trip will take around 30 hours.

The Seine could carry many more barges like Le Bosphore, which is longer than a soccer field and saves 18,000 truck trips a year between Le Havre and Paris. The government hopes to draw four times as much freight to the river as the 20 million metric tons it handles now each year.

To achieve that, Haropa has been accelerating an expansion of Le Havre port, which sits at the mouth of the Seine, in a bid to attract ships from the larger ports of Rotterdam in the Netherlands or Antwerp, Belgium. Cargo deposited at those ports is then driven to France on trucks.

At its five other port terminals on the Seine, Haropa is adding electrical stations that allow ships to plug in while docked, rather than running engines.

While much of Europe’s barge fleet is still powered by diesel, a small but growing portion is being adapted for biofuels. Electric boats are coming onto the market. Hydrogen-powered prototype barges are also being developed.

Companies like Ikea and river transport start-ups are helping to propel the movement. They are developing carbon-free last-mile delivery services to appeal to consumers — and to get ahead of strict environmental rules that European cities are imposing to limit heavy, polluting vehicles.

A Chain of ‘Cleaner Transport’

Eight hours after sailing from Le Havre, Le Bosphore pulled into Rouen, a major stop for river cargo to and from Paris. Around 10 a.m. a fresh four-person crew, led by Captain Badar, boarded for a weeklong shift, and the trip toward Paris resumed.

Barge traffic on the Seine has increased just 5 percent from a decade ago. While the government is trying to engineer an acceleration, “rivers have been neglected for too long,” said Captain Badar, the third generation of riverboat captains in his family. He is among a rare breed. Many riverboat captains in Europe are nearing retirement age, and there’s a shortage of qualified personnel, a problem that risks curbing the hoped-for growth in river traffic.

For centuries, Captain Badar noted, rivers were practically the only way to ferry goods through France: The ancient symbol of Paris is a boat. But waterways fell out of favor as trucks and trains dominated transport in the 20th century, especially after World War II, when highways and rail tracks expanded across the continent.

Governments support those industries “because they have powerful lobbies and unions,” Captain Badar said, navigating past a medieval castle built by Richard the Lionheart as the sun brightened the afternoon sky.

“Now we’re starting to talk about the environment, and it would be best to see the river as part of a wider chain of cleaner transport.”

France’s largest supermarket chain, Franprix, is ahead of the game. It has transported goods by barge for a decade to its 300 Parisian stores. Workers unload 42 containers each morning near the Eiffel Tower. That saves 3,600 truck trips a year on highways and has cut Franprix’s carbon emissions 20 percent, the company said.

Kitchen Cabinets and Coffee Beans

Le Bosphore pulled into Gennevilliers port the next morning before dawn, docking alongside other barges laden with wares for Parisian businesses. A crane unloaded three layers of containers from the hold, placing them on the pier, where forklifts stacked them to the side. Despite the voluminous cargo, Le Bosphore had consumed the fuel of only about four trucks on its entire trip.

Across the port, an experiment was underway to make the last mile of delivery more environmentally friendly: a hulking warehouse, set up in a 2022 deal between Haropa and Ikea, the Swedish furniture giant, to create a carbon-neutral way to deliver goods using the Seine.

Pallets packed with Ikea kitchen cabinets and couches, ordered online less than 48 hours earlier, were loaded onto a barge that would take them to central Paris. There, they would be put onto electric trucks and delivered to customers.

The process isn’t completely decarbonized — the barge to central Paris burns fuel, as do the trucks from Ikea’s factories in Poland and Romania — but the arrangement allowed Ikea to take the equivalent of 6,000 trucks off Paris streets last year, said Emilie Carpels, director of Ikea’s river project.

Other ventures are aiming to be more cutting edge.

Europe’s first hydrogen-fueled river barge, the Zulu, is expected to start operating in the spring. Designed by Sogestran, it can carry up to 320 metric tons, or the contents of around 15 trucks. “We are moving toward a future of increasingly clean transport,” said Florian Levarey, the project director.

For Fludis, a French start-up, that future is already at hand. Its president, Gilles Manuelle, founded the company around two boats that run on electric batteries, and a fleet of electric delivery bikes.

Around 7 on a recent morning, a dozen crew members loaded one of the small barges with boxes of coffee beans, copier paper, kitchen towels and other goods to be delivered to French bistros and businesses. As the boat sped silently past the Louvre for its first drop-off, workers onboard loaded their bikes with orders, and sped onto the streets as soon as the captain docked.

“We’re starting off small,” Mr. Manuelle said. “But it’s little solutions like this that can grow much bigger, and help play a role in reversing global warming.”

Back in Gennevilliers, the crew of Le Bosphore filled the now-empty hold with French goods for export: flour, lumber, luxury handbags and Champagne. By 2 p.m. it would begin a cruise back to Le Havre, where the crew would unload and then start all over again.

“I’ve known for a long time that the river was the most ecological means of transport,” Captain Badar said, easing back into the helm. “Now we need for policymakers to really make it happen,” he added. “The potential is huge.”