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Climate change: Does extreme weather cause more damage?

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A landslide and subsequent debris flows severely damaged the village of Bondo in the Grisons at the end of August 2017. Experts assume that such events will become more frequent due to climate change. The IPCC panel members say that the economic costs of extreme weather events have very probably already increased worldwide. This is reason enough for geographer Norina Andres to try to find out whether climate change has led to an increase in damage due to extreme weather in Switzerland.

Norina is responsible for the Swiss flood and landslide damage database, which is maintained by WSL and financed by FOEN. It has collected records of damage caused by floods, landslides and debris flows during the past 47 years. At first glance, the data seem to confirm the assumption that the cost of damage is increasing. However, is this really a consequence of climate change? As Norina says: “Nowadays everything is more expensive. People have more possessions, houses are more valuable and there are simply more buildings and other infrastructure.”

Reassessed to account for the conditions prevailing today

In order to take into account the influence of such socio-economic and demographic effects, the researcher and her colleague, Alexandre Badoux, have used three different approaches to process the damage data. “This enables us to estimate what damage events that happened many years ago would cause under today's conditions,” explains Norina. For her calculations, she used first the development of the gross domestic product, then the increase in the real income of the population and finally the building insurance values, taking inflation and population development into account.

“When we normalize the data like this, then we can see that the damage has not increased.”
Norina emphasises that her study does not call into question the existence of climate change. But in Switzerland it has not (yet) had a demonstrable effect on the amount of damage caused by floods, landslides and debris flows. On the other hand, inflation, and the development of the population and prosperity play a role. Switzerland is also investing a lot of money in protective measures. “Perhaps these measures can counterbalance any climate change effects,” Norina speculates – which would be really good news. (Birgit Ottmer, Diagonal 1/19)