Precise data is hard to come by in attempting to assess the damage done by a hurricane. For one thing, there is a great deal of long term and indirect damage that will never be included in the calculations. (Imagine, for instance, a truck driver in Pittsburgh who is distraught over his daughter’s sudden tragic death in flooded New Orleans after Hurricane Katrina, and who in his distracted state gets into a costly accident that otherwise likely wouldn’t have happened. These “ripple effects” of a tragedy aren’t going to show up in anyone’s statistics.)
As much as the figures for the United States are incomplete and involve guesswork, that is far more true for Third World countries. So to simplify matters, to identify the costliest hurricanes of the last century we'll look at damage in the U.S. only, for storms from 1900 to the present, using the best estimates provided by the National Hurricane Center (NHC) of the National Oceanic and Atmospheric Administration (NOAA). (The figures through 2004 have been adjusted by the NHC for inflation; those after 2004 have not. However, the inflation rate has been low in recent years, so the damage estimates for 2005-present shouldn’t be more than slightly overstated relative to the adjusted figures.)
Texas, Louisiana, Mississippi
Louisiana, Mississippi, Alabama, Florida
Perhaps what jumps out as much as anything from this data is how recent these storms have been. Four of the five costliest hurricanes in U.S. history have occurred since 2004, and even the other was less than 20 years ago. (Going farther down the NHC's list, seven of the top nine have been since 2004.)
Some will say this is a sign of human-caused climate change, of how we’ve messed up our environment and made more extreme, more erratic, more damaging weather likelier.
While this may be a partial explanation, there are plenty of other factors one can point to in addition or instead.
For one thing, more damage is caused in modern times simply because there are so many more people and so much more “stuff” that can be measured in dollars. If Katrina had struck New Orleans before New Orleans was founded, or when it had only a comparative handful of people, it wouldn’t have caused the damage it did in 2005, even adjusted for inflation.
There’s also the fact that in some cases the land has been altered in ways that make people in the area more vulnerable to hurricanes. Again using Katrina as an example, if so much Louisiana marshland hadn’t been wiped out so that certain industrial activities could be even more profitable, there would have been much more of a “buffer zone” to slow down the storm before it reached the more populated areas.
Another easily overlooked factor is the market-skewing government subsidies for flood and disaster insurance in coastal areas. Lobbyists for real estate interests and wealthy home owners have succeeded in gaining much financial relief for people who build in risky areas where otherwise the insurance rates would be exorbitant. It’s great to have a big fancy house or business on the ocean, but critics argue that there are far more of those than there would otherwise be since one of the indirect costs of building them has been socialized. So they are now in reach of the major storm that wouldn’t have touched them had they been built farther inland.
Whatever the various reasons, hurricanes have been more devastating than ever in recent years. Only time will tell if that will continue (or get even worse).