With an official damage tally of $65 billion, Hurricane Sandy was the second most destructive storm in U.S. history, falling behind only Hurricane Katrina at $108 billion. But Sandy was not the worst storm imaginable for the eastern coast of the U.S. In fact, says a recent study from reinsurance firm Swiss Re, a storm that actually roared up the U.S. coast almost two centuries ago would do far more damage than Sandy did, were that storm to occur in the present day.

USA Today has a report on the Swiss Re study (see "1821 hurricane trumps Sandy, would have cost $100B," by Todd B. Bates, Asbury Park Press). Imagine, the report says, a Category 4 hurricane coming on shore at Cape May, N.J., rolling up the Garden State Parkway and slamming into New York City before proceeding on through central New England. That storm could easily do $100 million in damage, and overwhelm local and state government's disaster response capabilities.

And that storm has happened — but it was back in 1821, when the region was home to barely 150,000 souls. Says the Swiss Re study author, meteorologist Megan Linkin: "It could very well happen again."

Linkin's report, "The big one: The East Coast's USD 100 billion hurricane event," is hosted at the Swiss Re website. The gist? "Trillions of dollars of assets and infrastructure would lie in the storm's path, much of it aging and along the coast," says Swiss Re. "Using our in-house, proprietary tropical cyclone model we reconstructed the storm track, wind field, and potential storm surge and concluded that a large area of the most heavily developed Eastern Seaboard would be exposed to hurricane force wind gusts. Storm surge comparable to Sandy would inundate New York City, accompanied by powerful winds gusting over 100 mph. Norfolk, Virginia - home of critical US Navy installations - would be completely flooded. Coastal counties would sustain wind damage alone in excess of USD 1 billion. Combined physical damage from both storm surge and wind would exceed USD 100 billion, while the storm's total potential economic impact is on the order of USD 150 billion."

After Sandy, some news reports quoted hurricane experts who explained that Sandy's unusual path was a rarity caused by an odd confluence of atmospheric effects. And that's true, writes Megan Linkin — but it could be misleading. While a storm just like Sandy is unlikely to recur, a different (but even worse) storm is quite a bit more likely to happen instead.

Writes Linkin: "It's highly unlikely that we will see a hurricane with the same characteristics as Sandy. However it's very likely (1 in 50 years) that we will see, and in fact, have seen, other hurricanes in the Northeast that would have caused economic damages equal to or greater than those caused by Hurricane Sandy if they were to occur today. Sandy is a harsh reminder of what greater event potentially awaits us."

"Furthermore," Linkin adds, "we must continue to be mindful that our coastal risk landscape is going to shift upwards due to climate change and sea level rise. Since the 1850s, the sea level has risen by a foot and a half at the Battery in New York City. This additional 18 inches of sea level exacerbated Sandy's tremendous storm surge. If this trend continues, as it's expected to, hurricanes much smaller and weaker than Sandy will be capable of generating storm surges and damages comparable to or exceeding that of Sandy."