|Above: A man looks at hundreds of shoes displayed in memory of those killed by Hurricane Maria in front of the Puerto Rican Capitol, in San Juan on June 1, 2018. Image credit: Ricardo Arduengo/AFP/Getty Images.|
Hurricanes are responsible for the greatest number of deadly U.S. weather events of the past 50 years, claiming nine of the top thirty spots, if we look at weather events lasting a month or less. By this definition, winter storms and their associated severe weather and flooding had the second highest number of deadly events (seven), followed tornado outbreaks (five), then floods and heat waves (four each). One wildfire made the list, the 2018 Camp Fire in California.
America’s deadliest disaster of the past fifty years was Hurricane Maria, with a direct plus indirect death toll of 2981. However, if we consider summer-long heat waves as being weather events, the two deadliest would be the heat wave of 1980 (10,000 direct and indirect deaths) and the heat wave of 1988 (5000 direct and indirect deaths).
Lots of caveats
Determining the death toll from a disaster is a difficult task subject to large uncertainties. The numbers reported here are for both direct and indirect deaths. A direct death occurs due to a storm’s winds and rains directly, while an indirect death can be due to traffic accidents during a evacuation, lack of life-saving medical care due to a power outage, etc.
The numbers reported for hurricanes, winter weather, floods, and tornado outbreaks were taken from NOAA’s list of billion-dollar weather events--with the exception of hurricanes prior to 2016. I pulled those numbers from a 2016 paper, Fatalities in the United States Indirectly Associated With Tropical Cyclones, by Ed Rappaport, the Deputy Director of the National Hurricane Center. He computed direct and indirect deaths using conclusions of medical practitioners wherever possible, and then raw data obtained directly from one or more of the official sources, such as coroners’ offices, emergency managers, and law enforcement officials.
For the special case of Hurricane Katrina of 2005, he elaborated on the death toll in an email to me: “At this point, I've got Katrina with 520 direct deaths and 565 indirect deaths. But, there were also 302 fatalities in Louisiana of indeterminate cause. That is, the LA State Office of Epidemiology list of fatalities included 302 individuals for whom no cause of death was identified. The total Katrina death toll would be 1085 - 1389, with direct deaths being 520 - 822. As for drowning in New Orleans, it would currently be 341 - 643.”
The actual indirect death toll from Katrina was likely much higher; one 2007 study that drew on death notices in the New Orleans Times-Picayune, the leading local newspaper, estimated that there were 2358 excess deaths in the local area during the months of January - June 2006, in the aftermath of Hurricane Katrina, compared to the years 2002 - 2004. These would have been on top of all Katrina-related deaths that occurred from September to December 2005.
Figure 1. Photo taken in Waveland, Mississippi during Hurricane Katrina’s storm surge by Judith Bradford, who rescued the man shown floating on the remains of his house. From Margie Kieper’s excellent series on Katrina’s storm surge, we have this description: At 8:30am, storm surge water started coming into their yard. Their home is 18 inches off the ground, and the first floor has 8-foot ceilings. There is an 18-inch truss between the 1st and 2nd floors, and this is what saved their 2nd floor from being flooded. In a matter of only five to ten minutes the water came up six feet, and quickly filled the first floor after that. Judith said that is why they saved so little from the first floor; they had no time to get anything. She first tried to shut the living room front door, but the force of the water burst the door open. She grabbed a camera, and the Bradfords and their children ran upstairs. They marked the high-water mark (HWM) on the inner stairwell showing how high the water came--a little more than six more inches into the truss, which is a total of 10 feet of surge. The man in the photo they saved was a chef named Glen. He was holding a four-month old dachshund named Pinky. He had lost his other dog and three cockatiels when his mother's home collapsed. The roof wedged against the Bradford’s van, underwater, and stopped, allowing Bill Bradford to swim out to rescue Glen. BIll reported that the water was so warm, it seemed almost hot, and that he current was nothing like white water, but was a gentle continuous flow.
America’s deadliest disaster of the past fifty years was Hurricane Maria, with NOAA listing a direct plus indirect death toll of 2981. As explained in an August 2018 post by Bob Henson, this death toll was arrived at using statistical methods of computing excess mortality based upon a study done by George Washington University in collaboration with the University of Puerto Rico (commissioned by the Puerto Rico government). This was a different method than the National Hurricane Center uses to come up with their indirect hurricane death tolls. The official toll from NOAA included 2975 deaths from Puerto Rico and six direct deaths in the U.S. Virgin Islands. A separate excess mortality study of deaths was not performed there; that territory was affected even more severely than Puerto Rico, and has a population about 3% of Puerto Rico’s.
The numbers for heat wave deaths were pulled from EM-DAT, the international disaster data base. These numbers were just for direct deaths, and I included only those heat waves that lasted a month or less. EM-DAT and NOAA’s list of billion-dollar weather events both had entries for very deadly heat waves lasting two or more months which affected the entire country. I did not consider these to be weather events in the same sense as a storm, tornado outbreak, or heat wave that affected a more limited portion of the country and which lasted a few days or a few weeks.
Hot summers and cold winters dominate as the deadliest weather events
If we include season-long heat and cold as being weather events, and tally up their direct and indirect death tolls, the list of top-twenty deadliest U.S. weather events of the past 50 years would become dominated by hot summers and cold winters.
Direct deaths due to cold weather in the U.S. averaged about 1300 per year between 2006 to 2010, according to a 2014 study by the CDC. As I explained in my previous post, this is likely an underestimate. A 2011 study, An evaluation of the progress in reducing heat-related human mortality in major U.S. cities, found that heat killed approximately 1300 people per year in 40 major U.S. cities between 1975 - 2004. This is also an underestimate, since the full population of the nation was not considered.
The CDC does not supply a year-but-year breakdown of the number of heat deaths and cold deaths for the U.S. If such a list existed, Hurricane Maria (2981 direct and indirect deaths) would probably be the only non-heat or non-cold event to make the top-thirty list of deadliest U.S. weather events of the past 50 years. The two deadliest events would likely be the heat wave of 1980 (10,000 direct and indirect deaths) and the heat wave of 1988 (5000 direct and indirect deaths).