US hurricane seasons are costlier than before because more Americans are living in coastal states and building bigger and more expensive homes, the Insurance Information Institute says.

CEO Sean Kevelighan says people increasingly moving into areas prone to natural catastrophes are playing a greater role than either weather or climate when it comes to impacting claim payouts after hurricanes.

Warmer oceans are also contributing, though it is the demographic changes that most contribute to the startling rise in hurricane-related costs, he says, pointing to the rising number of “bigger homes filled with more valuables, more vehicles – all the infrastructure that goes with increasing populations”.

Last month Hurricane Laura became the latest storm to generate multi-billion-dollar claims. Nine of the 10 costliest hurricanes in US history have occurred since 2004, and 2017-2019 brought the three highest insured property loss years in US history.

“Many would instinctively chalk up such numbers to climate change, but a careful look at the data reveals a picture in which climate change, while playing a role, is not necessarily the predominant driver of hurricane-related financial losses,” the institute says.

Hurricane-related losses continue to climb despite improved forecasting, more data and advanced analytical tools, greater public awareness and pre-storm communication and improved materials and engineering.

“The data suggest that demographic changes play a greater role in natural catastrophe-related claims and losses than weather and climate do,” the III says.

“Even a modest rise in the number of landfalls – or no rise at all – could yield the sorts of increased losses the industry has been seeing over the past few decades.”

Repairing and replacing large wind-damaged homes are among the reasons insured loss payout figures continue to climb after hurricanes, despite improved weather forecasting and greater public awareness.

“Implementing modern building codes would go a long way toward mitigating losses from hurricanes and other natural disasters and helping communities and businesses bounce back after such events,” it says.

Inland flooding has caused more deaths in the United States in the past 30 years than any other hurricane-related threat and hurricanes appear to be getting wetter as over warmer oceans, and tropical cyclones are intensifying at a faster rate than they ever have before.

Flash flooding from intense rainfall impact far more people and stretch over a much larger area than wind speeds and storm surge.