PARIS • Firefighters from across Europe struggled Thursday to contain a huge wildfire in France that has swept through a large swath of pine forest, while Germans and Poles faced a mass fish die-off in a river flowing between their countries.

Europe is suffering under a severe heat wave and drought that has produced tragic consequences for farmers and ecosystems already under threat from climate change and pollution.

The drought is causing a loss of agricultural products and other food at a time when supply shortages and Russia’s war against Ukraine have caused inflation to spike.

In France, which is enduring its worst drought on record, flames raged through pine forests overnight, illuminating the sky with an intense orange light in the Gironde region, which was already ravaged by flames last month, and in neighboring Landes. More than 26 square miles have burned since Tuesday.

The French wildfires have already forced the evacuation of about 10,000 people and destroyed at least 16 houses.

Along the Oder River, which flows from Czechia north into the Baltic Sea, volunteers have been collecting dead fish that have washed ashore in Poland and Germany.

Piotr Nieznanski, the conservation policy director at WWF Poland, said it appears that a toxic chemical was released into the water by an industry and the low water levels caused by the drought has made conditions far more dangerous for the fish.

“A tragic event is happening along the Oder River, an international river, and there is no transparent information about what is going on,” he said, calling on government authorities to investigate.

People living along the river have been warned not to swim in the water or even touch it.

Poland’s state water management body said the drought and high temperatures can cause even small amounts of pollution to lead to an ecological disaster but it has not identified the source of the pollution.

In northern Serbia, the dry bed of the Conopljankso reservoir is now littered with dead fish that were unable to survive the drought.

The water level along Germany’s Rhine River was at risk of falling so low that it could become difficult to transport goods — including critical energy items like coal and gasoline.

In Italy, which is experiencing its worst drought in seven decades, the parched Po River has already caused billions of euros in losses to farmers who normally rely on Italy’s longest river to irrigate their fields and rice paddies.

“I am young and I do not remember anything like this, but even the elderly in my village or the other villages around here have never seen anything like this, never ever,” said Antonio Cestari, a 35-year-old farmer in Ficarolo who says he expects to produce only half his usual crops of corn, wheat and soy because his river-fed wells have such low water levels.

The Po runs 405 miles from the northwestern city of Turin to Venice. It has dozens of tributary rivers but northern Italy hasn’t seen rainfall for months and this year’s snowfall was down by 70%. The drying up of the Po is also jeopardizing drinking water in Italy’s densely populated and highly industrialized districts.

Over in Portugal, the Serra da Estrela national park was also being ravaged by a wildfire. Some 1,500 firefighters, 476 vehicles and 12 aircraft were deployed to fight it but the wind-driven blaze 150 miles northeast of Lisbon was very hard to reach, with inaccessible peaks 6,560 feet high and deep ravines. The fire has charred 25,000 acres of woodland.

In Britain, where temperatures hit a record 40.3 degrees Celsius (104.5 degrees Fahrenheit) in July, the weather office has issued a new warning for “extreme heat” from Thursday through Sunday, with temperatures forecast to reach 36 C (96.8 F).

It has been one of the driest summers on record in southern Britain, and the Met Office weather service said there is an “exceptional risk” of wildfires over the next few days.