Increasing costs of hurricanes

"The growth of the coastal population and exposure is certainly the predominant factor in the increased costs of damage associated with hurricanes," says Steve Bowen, director and meteorologist at the consulting firm

Aon
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Risk Solutions Division.

Rising costs of the storm

The United States has recorded 40 hurricanes since 1980, calculated on the basis of inflation-adjusted dollars for 2018, with a cumulative damage estimate of $ 862 billion, according to a National Oceanic and Weather Disaster Analysis. Atmospheric Administration.

The trio of Harvey, Maria and Irma in 2017 cost $ 268 billion, 31% of the damage since 1980, making it the most expensive year in 38 seasons. According to Moody's estimates, Florence caused less damage than those storms. At the top of the damage estimate of $ 38 billion to $ 50 billion, it will rank among the strongest storms since 1980.

Location, not wind

The strength of the wind is not the only factor that determines how bad a storm will be. Florence made landfall in the Carolinas as a Category 1 hurricane, due to the strength of the wind. The devastating effect of Florence, like Harvey in 2017, was mainly related to the floods.

The relatively weak storms are among the most expensive. "The wind category does not fully capture the cost of damage from historic hurricanes," says Adam Smith of the National Oceanic and Atmospheric Administration. Many population centers and infrastructure exist in vulnerable areas such as coasts and flood plains.

For storms like Harvey, changes in land use associated with urbanization, such as replacing permeable surfaces such as grass by impervious surfaces like concrete, can result in large changes in the runoff of water.

By the time he landed in 2012, Sandy had gone from a hurricane to what is known as an "extratropical" storm, but he hit large population centers causing "major damage." in several northeastern states ". the United States since 1980 with damage of $ 72.19 billion according to NOAA analysis.

Slower and wetter

Another contributing factor to the severity of Florence was the fact that the storm persisted in the area, flooding eastern North Carolina.

According to NOAA atmospheric scientist Jim Kossin, the speed at which North Atlantic hurricanes cross the earth has decreased by 17% from 1949 to 2016. Kossin published an article on the subject in Nature in June. Other things being equal, if you slow down the speed of a 17% storm, you will increase the rain by 17%, which will lead to a substantial increase in freshwater flooding.

Homes at risk

"With more people living in hurricane-prone areas, the damage is likely to increase," says Phil Klotzbach, a researcher with the Department of Atmospheric Sciences at Colorado State University.

According to CoreLogic, 6.9 million homes are likely to suffer hurricanes during hurricanes along the Atlantic and Gulf coasts, 67% of which are located in 15 metropolitan areas. The value of reconstruction costs – the cost to completely rebuild homes at risk in a 100% destruction scenario in 2018, including labor and materials – is $ 1.6 trillion.