Billion dollar weather disasters in the United States have increased dramatically over the last 30 years, according to the annual “State of the Climate” report in the August edition of the Bulletin of the American Meteorological Society.

The first graph at right shows the number of disasters per year. From an average of 1.8 per year in 1980 – 1984, the number has increased almost five-fold, to an average of 8.8 per year in 2008 – 2012. The black line shows the trend over the period.

Damages have also increased: from an average of $15.7 billion in 1980 – 1984 to an average of 67.6 billion in 2008 – 2012. That is more than a four-fold increase. The second graph at right shows the amount per year. The black line shows the trend over the period. Dollar amounts have been adjusted for inflation using the CPI.

Deaths, however, have not increased, they have declined. The third graph at right shows the number of deaths each year.

The chart of deaths is the least complex to understand, so let’s start there. Weather related deaths occur each year, but large weather-related disasters don’t automatically cause lots of fatalities. There are three large spikes in the number of deaths: 1980, 1988, and 2005. The spike in 2005 was almost entirely from Hurricane Katrina. The other two were from powerful heat waves that caused increased death rates due to heat stress. The trend is toward fewer deaths. Because the decline can’t be attributed to a decline in the number or power of the disasters, I suspect that we have improved our ability to anticipate them, take appropriate protective action, and respond once they do occur.

Damage from the weather-related disasters shows the significant variability from year-to-year. There is a huge spike in 2005; that was the year that multiple catastrophic hurricanes struck the United States. Damage from Hurricane Katrina alone was greater than the total loss for all of 2012 (which included Hurricane Sandy in New York)! The graph shows other spikes in 1988, and 2012. The damage in 1988 was mostly from a drought and heat wave in the eastern and central U.S. In 2012, it was mostly from Hurricane Sandy, but also from a drought and heat wave. While there is a correspondence between the number of disasters and the total damage, it is far from perfect (correlation = 0.41). It depends a great deal on the kind of disaster and where it occurs.

The number of disasters shows the least variability between years, and the most consistent trend.

Since the data has been inflation adjusted, the increase in the number of disasters and the damage they cause are probably not related to inflation. One possible explanation might be that increased development has put more property in harm’s way. This might be especially true in coastal areas that are vulnerable to hurricanes. Another possibility might be that weather extremes are more extreme than they used to be. Although previous posts showed that the number of powerful tornadoes has not increased, heat waves, floods, or hurricanes may have. This data does not say.

The next post takes a look at similar data for Missouri.

Sources:

Smith, A., Sidebar 7.1: Billion-Dollar Weather and Climate Disasters: 2012 in Context, [in “State of the Climate in 2012, Bulletin of the American Meteorological Society, 94, (8), S151. Downloaded from: http://www.ncdc.noaa.gov/bams-state-of-the-climate/2012.php.

Billion-Dollar Events, Billion-Dollar Weather/Climate Disasters, National Climatic Data Center, http://www.ncdc.noaa.gov/billions/events.