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Climate change predicted to cause rise in severe weather events

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Climate change is likely to cause an increase in the frequency and intensity of severe tropical cyclones and other weather events, according to a new report by catastrophe modeler AIR Worldwide.

The overall number of tropical cyclones and extratropical cyclones is likely to decrease due to a projected decline in the number of “weak” storms, but the frequency and intensity of the most “strong to extreme” tropical cyclones that are categories 4 and 5 on the Saffir Simpson Scale are expected to rise, according to the new report, Climate Change Impacts on Extreme Weather, by Boston-based AIR.

The Earth is also likely to experience an increase in the frequency and intensity of most of the other weather phenomena reviewed in the report, including severe thunderstorms, wildfires, inland floods and coastal floods. The effect of climate change is most evident for inland and coastal floods, both of which will overall see more frequent and more intense floods, according to the report.

However, there is much greater uncertainty around how climate change will affect “strong to extreme” events — 50- to 250-year return periods — compared with the more common “weak-to-moderate events” — two- to 10-year return periods — because existing historical data is insufficient and numerical climate models still do not simulate the most extreme events very well, the report found. A return period is an estimate of the likelihood of an event such as an earthquake or flood to occur.

“Many in the insurance world are paying increased attention to climate change in light of reports of increasing variability of atmospheric perils such as windstorms and floods,” Peter Sousounis, assistant vice president and director of meteorology at AIR Worldwide and co-author of the report, said in the report. “Meanwhile, regulators and rating agencies are beginning to ask companies to disclose how they are incorporating climate risk into their decision-making processes. As a result, clients have asked AIR to keep them apprised of the current state of the science regarding climate change impacts on extreme weather.”