VIENNA, Austria — Fire and floods have engulfed Europe this summer, as a relentless drought in Spain and Portugal transformed swaths of woodland into a massive tinderbox and torrential rains carved a trail of destruction through alpine valleys and Balkan villages.

Entire sections of the Swiss capital Bern have been submerged, blazes flare up even as old ones are snuffed out, and dozens have been killed in a third straight summer of extreme European weather that has people asking: Why?

Salvano Briceno, the 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.

But Dale Mohler, the director of international forecasting at AccuWeather.com., said neither the fires nor flooding this summer are all that uncommon.

"People wonder, hey, what's going on with our climate," said Mohler.

He said heatwaves 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 that have claimed at least 42 lives in central and southern Europe are not that unusual either.

"Is the world coming to an end? No -- at least not today or tomorrow," he said.

Some even suggest that there is merely a false perception of an increase in such natural disasters as a result of the heightened ability of the media to beam images of destruction instantly all over the world.

The flooding has cut off western alpine valleys in Austria, sent walls of water as high as four meters (13 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.

Still, Mohler said the disasters do not compare either in rarity or scope to phenomena such as the record-breaking heat in France in 2003 that killed nearly 15,000 people and 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 has contributed to flooding is overdevelopment, which has intensified in recent years as more and more people have moved to the suburbs or built second homes in the countryside, Anton Schleiss of Lausanne's polytechnic school told Switzerland's Radio DRS.

Development has blunted nature's ability to contain flooding, such as allowing rivers to flow more naturally and thereby enable them to better absorb high water levels, Schleiss said.

The draining of marshlands -- mostly for agricultural purposes -- results in harder, less porous ground. The straightening of rivers and their often artificial banks to reclaim land for agriculture or construction gives them less capacity to absorb water.

More compromise is needed among interested parties -- including farmers, homeowners and ecologists -- to allow greater protection against overdevelopment, Schleiss said.

"You can't win the race against natural dangers," he said.

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Associated Press Writers David Nauer in Bern and Uta Harnischfeger in Geneva and Joanna Mateus in Lisbon, Portugal contributed to this story.

Source: Associated Press