Switzerland's top environment official Philippe Roch says Hurricane Katrina and the storms that have hit Europe are a clear indication of global warming.
The head of the Swiss environment agency warned on Thursday that Switzerland could face an increased incidence of natural disasters, and said maps were being prepared to identify the areas at greatest risk.
Roch was speaking to swissinfo after violent storms brought flooding to southern France – the latest in a series of weather-related disasters.
Floods devastated large swathes of Europe – and parts of Switzerland – last month. And in the wake of the flooding, Hurricane Katrina struck the Gulf Coast of the United States laying waste to New Orleans.
"These are typically phenomena described by the models for climate change. So the link is for me personally really evident," Roch said.
He added that a change in human behaviour could explain why these natural phenomena were wreaking so much destruction. Buildings were being constructed in areas which previously had been left untouched.
"I don't know the historic situation in New Orleans but... with the expansion of human kind we are trying to live next to rivers and on low lands and this increases the damage when such phenomena occur."
Roch said that Switzerland's progressive environmental policies had limited the extent of the flood damage.
"Our policy of forest protection has been very positive, because without these forests the damage would have been much much greater and we would have probably had many more casualties.
"Secondly, we have completely changed our policy towards water. We now try to enlarge the space for rivers and are funding the renaturalisation of our rivers, which is a very good policy."
Roch praised the preparedness of the cantons and the municipalities for dealing with flooding, but warned that natural disasters were likely to become more frequent as the climate heats up.
"That's why we are now creating new risk maps to avoid building infrastructure in areas that are under threat," he told swissinfo. "We have to adapt to the new situation by developing a long-term prevention strategy."
"We have to continue our policy against climate change but we will not be able to curb the phenomena in the short term."
swissinfo, Morven McLean
Floods swept across central and eastern Europe in the second half of August. In Switzerland six people died and the total damage was estimated at up to SFr2 billion ($1.6 billion).
After battering the state of Florida, Hurricane Katrina struck America's Gulf Coast on August 29 wreaking havoc in the states of Louisiana, Mississippi and Alabama. Thousands of people in New Orleans and coastal areas are believed to have died.
Violent storms hit southern France on September 6, flooding parts of the Languedoc region.