Bern, Switzerland ? When the Aare overflowed, its muddy waters swallowed driftwood, strollers, bicycles, even cars – debris that bobbed along as the river flowed through the cobblestone streets of Bern.

Residents devastated by the flooding this week also wept Thursday when the waters receded.

Not only were their homes damaged, but they couldn’t even return to them. Police evacuated dozens more people and stopped others from reaching their houses, fearful the Aare might surge back and once again subsume whole sections of the city.

Fire and floods have engulfed Europe this summer. A relentless drought in Spain and Portugal transformed swaths of woodland into a massive tinderbox. Torrential rains carved a trail of destruction through picturesque European cities, Alpine valleys and Balkan villages.

And dozens have been killed in a third straight summer of extreme European weather that has people asking: Why?

“It really hits home when you see something like this,” said fire service chief Franz Bachmann, who led the evacuation operation in Berne, a UNESCO World Heritage Site. “Lots of people have lost their whole existence.”

An overturned car lies in the mud Thursday in front of a house in Brienz in the Berner Oberland region, Switzerland. Water levels remained high on many rivers and lakes in central Switzerland, hard hit by the torrential downpours that swamped central and southern Europe earlier this week, although many victims have begun returning to their homes and villages.

At least 42 people have been killed in floods alone. Hardest hit was Romania with 31 victims, many who drowned when water rushed in their homes. Austria, Bulgaria, Germany and Switzerland reported a total of 11 dead. Numbers were expected to climb as more bodies were recovered.

Global warming linked

Salvano Briceno, head of the U.N.’s International Strategy for Disaster Reduction, warned that Europe should expect more severe rains because of global warming and called for efficient early warning systems.

“It is incredible that people in a country like Switzerland are dying because of floods. But people forget easily how vulnerable they are. We should always be ready to face natural hazards,” Briceno said.

Horrific as the damage may be, Dale Mohler, the director of international forecasting at AccuWeather.com., said neither the fires nor floods this summer are all that uncommon.

He said heat waves like the one that has scorched Portugal and Spain – contributing to fires that have left stretches of forest looking like barren winter landscapes – have occurred every 15 to 20 years. And the floods in central and southern Europe are not that unusual either.

“Is the world coming to an end? No – at least not today or tomorrow,” Mohler said.

Flooding cut off western Alpine valleys in Austria, sent walls of water as high as 12 feet crashing over villages in Romania and forced authorities in Switzerland to pluck residents from their homes and evacuate them by helicopter.

Blazes in Portugal have killed 15 people, destroyed farmland, and forced hundreds to be evacuated from their homes.

On the one hand, Mohler said, these disasters do not compare in rarity or scope to phenomena such as record-breaking heat in France in 2003 that killed nearly 15,000 people, or last year’s hurricane in Brazil, considered the first such recorded storm in the south Atlantic.

But environmental groups like the World Wildlife Fund argue that global warming has intensified the impact of the weather events.

Martin Hiller, a spokesman for the group, said that while it was difficult for anyone to connect one specific disaster to climate change, the increasing number of them and their intensity suggest they are connected to global warming.

“We are linking these (extreme weather) events to climate change,” he said. “It is not the only reason. There are also other things happening – building up the land, bad land use plans, bad fire prevention in the south, for instance in Portugal – but all the factors together are more and more exacerbated by global warming.”

In Switzerland, one factor that contributed to flooding is overdevelopment, which has intensified in recent years as more people move to the suburbs or build second homes in the countryside, Anton Schleiss, of Lausanne’s polytechnic school, told Switzerland’s Radio DRS.