Effects of climate change increasingly influencing U.S. thunderstorm losses: Munich Re

Losses from an average severe thunderstorm in the United States have increased significantly since the end of the 1980s, supporting the finding in a peer-reviewed study that changing climatic conditions have already influenced those losses.

The research was produced in connection with a co-operation project between Munich Re and the German Aerospace Center. “Some regions already need to adapt to changing weather risks,” Dr. Peter Röder, a member of Munich Re’s Board of Management, notes in a statement from the global reinsurer.

“This concerns the insurance industry as risk carrier, first and foremost, but also those in the private and public spheres responsible for deciding on prevention measures,” Dr. Röder continues.

Covering the 1970 to 2009 period, the study examines hail, tornado, thundersquall and heavy rainfall events in the U.S. with losses exceeding US$250 million (past losses were extrapolated to current socio-economic conditions).

Severe thunderstorms caused US$47 billion in economic losses south of the border during the record year of 2011, Munich Re reports. The losses were at about the same level as those from a medium hurricane.

“After adjusting the losses to take account of socio-economic changes, increases still remain, which cannot, therefore, be explained by changes in exposed values,” notes the statement. “They are, however, correlated with the increase in meteorological potential for severe thunderstorms and its variability revealed by the study. It has, thus, been possible for the first time to scientifically prove that climatic changes have already influenced U.S. thunderstorm losses.”

Severe U.S. thunderstorm losses have not only increased significantly from the end of the 1980s, fluctuations between the years have been more extreme.

Although unable to conclusively differentiate the influence of the natural and man-made components of climate change, study co-author Eberhard Faust reports the change in losses is largely driven by changes in climatological boundary conditions. “In particular, the potential energy required in the atmosphere for the formation of severe thunderstorms has increased in the course of time,” says Faust, part of Munich Re’s Geo Risks Research.