People gather beneath holiday decorations as free dinner is served at a distribution relief tent for those affected by Superstorm Sandy on December 23, 2012 Staten Island, New York. - 

In 2012, the U.S. saw 11 disasters that each cost $1 billion or more, the National Oceanic and Atmospheric Association estimates. The key events: Hurricane Sandy and the drought. Each event may end up costing $50 billion or more in losses.

The costliest year was 2005, the year of Hurricanes Katrina and Rita. But, costly events are not necessarily the most ferocious.

"More and more people, and more and more businesses, are located in harm's way," says Robert Hartwig of the Insurance Information Institute, "so there simply is more that can be damaged and destroyed by hurricanes and other tropical events."

Insurance firms are on the hook for some damages. But in many exposed areas, like the Florida coast, companies are ditching the market. That often leaves state and federal governments on the hook.

"What does it mean when the insurance company won't provide insurance?" asks Mindy Lubber of the nonprofit Ceres, which works with investors and businesses on climate issues. "It means the federal government and you and me -- the taxpayers -- we become an insurance company."

Ten of the 12 costliest hurricanes have hit in the last decade. Which means, private or public, somebody's wallets are getting walloped.

Follow Scott Tong at @tongscott