This summer, sweaty Estonians doused fires in Sardinia and Romanians fought flames in France as part of an urgent bid to save a burning continent. The European Union is more familiar with trade policy than fighting infernos. Yet faced with ever-longer fire seasons across a widening territory, Brussels is stepping up, in part by positioning firefighters on loan from other European countries in high-risk regions.

The program started in 2022 with 236 firefighters and has expanded to include nearly 800 this summer. They are coordinated from a round-the-clock emergency response hub in Brussels. A small team there also answers calls for backup when fires grow too big for one country.

The European Union coordinates help from around the region, and it is building its own fleet of firefighting helicopters and planes, creating a backup force that nations can call on. The question is whether Europe can scale up its capacities fast enough to combat the fires burning through Spanish forests, along French coastlines and across Greek islands each year. Both national governments and the E.U. are trying to rapidly increase their capacity to respond.

The Italian island of Sardinia, which faces many fires, formally used the program to preposition firefighters for the first time this year. On a swampy day in mid-August, a team of Estonian and French firefighters milled about at a dusty base camp on the southern part of the island. The Estonians wore lightweight gear bought specifically for the trip.

Daniela Pani, a local Italian who coordinated the force, said working with international teams helped volunteers on the ground and gave the professionals from abroad a chance to share firefighting skills. For Grégory Fabre, who had left France during a historically bad fire season to lead his unit’s Sardinian tour, the experience of battling flames on the island could soon be useful back home. Sardinians have strategies for fighting fires when water resources are scarce, he said, like lighting opposing fires to suck up oxygen and help snuff out the uncontrolled blaze. “The techniques are different,” he explained in French.

He had a language barrier with his hosts, as did most of the French team — but they didn’t seem bothered. “When you are fighting a fire,” Ms. Pani explains, “you don’t need to make fluent conversation.