If it seems as though there are a lot more news stories than there used to be about billion-dollar weather disasters, it’s not your imagination and it’s not “fake news.” It’s because there are a lot more billion-dollar weather disasters than there used to be.
NOAA has released their latest data on billion-dollar weather disasters striking the USA (corrected for inflation of course). The number of such disasters per year, and their total cost, are both trending upward, those trends are “statistically significant,” and last year (2023) set a new record for the most such events, although it didn’t come close to 2017’s record cost of nearly $400 billion:
Clearly “more disasters” doesn’t always equate to “more cost” because not all weather disasters cost the same. In fact, not all weather disaster types tend to cost the same. NOAA has conveniently separated the billion-dollar disasters into 7 categories:
1: Drought
2: Flood
3: Freeze
4: Severe Storm
5: Tropical Cyclone
6: Wildfire
7: Winter Storm
The one that’s costing us the most is Tropical Cyclone (I’ll call it “TC”), to the tune of $31.3 billion per year. That’s the average for the period of record from 1980 to now, but the last 10 years have cost more, about $67.6 billion per year. The increase is mainly because there are more TCs bringing billion-dollar disasters to our shores; the overall average is 1.4 such events per year, but over the last decade it has been up to 2.4.
The simple fact is that TCs are the most expensive on a per-event basis, and that’s how they take the “gold medal” for highest average cost per year, and how 2017 set the all-time cost record when a mere 3 TCs cost over a $300 billion.
The “silver medal” for the 2nd-highest cost goes to Severe Storm (we can call it “SS”), at $10.3 billion per year. It earns a spot in the top three not by costing the most on a per-event basis (it actually costs the least of al 7 categories), but by occuring so often: over the 44 years of record there have been an average of 4.2 billion-dollar storms per year. Lately (over the last decade) it has been even higher, with 10.4 billion-dollar storms per year, raising the average cost to $24.1 billion per year.
The bronze medal is in dispute, because over the entire record the 3rd-costliest type has been drought at $8 billion per year, but I award it instead to Wildfire because over the last 10 years that has moved into third place at $10.4 billion per year. Both of these categories share an unusual way of counting, that each year’s count is 0 or 1, i.e. there either is or isn’t a billion dollars damage from that category in the given year.
The trends of individual categories also tell an interesting story. Both drought and flood show an increasing trend in number, but not in cost. Billion-dollar freeze events have significantly reduced their cost but not their number. For the big 3, TC and SS and wildfire, the increase is statistically significant for both the count and the cost. One category, Winter Storm, does not show a significant trend.
Some might think this increase in weather disasters and their cost takes a horrible toll on human life, bringing suffering to millions of people. Some might mention the unfairness that the wealthy can buy their way out of danger while the underpriveleged are doomed to suffer the consequences.
And some might recognize that these are statistics about billion-dollar weather disasters. Whatever the cost in human suffering, and however unfairly the pain might be spread around, there is no doubt that the cost will ultimately fall on all of us; this much economic damage, year after year, takes a toll on all of our lives and prosperity. Even the most die-hard conservatives — the smart ones, at least — are coming to realize this.
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There are some issues with the dataset. The biggest is that it only adjusts for inflation, so that increased population and increased “stuff” that each individual household isn’t taken into account. Something like Current-Cost Net Stock of Fixed Assets and Consumer Durable Goods takes that into account. From 1980-2022, it went up by a factor of 9. Inflation’s gone up by a factor of 3. Inflation-adjusted, a $100 million damage event in 1980 would produce ~$300 million in damage now. We explored this with respect to tornadoes a couple of decades ago. https://journals.ametsoc.org/view/journals/wefo/16/1/1520-0434_2001_016_0168_ndfmti_2_0_co_2.xml
Every time I’ve pointed this sort of thing out to a “skeptic,” the response is always that the real reason for the increasing costs is that the US is more built-up every year.
In other words, more stuff gets wrecked because there’s more stuff TO wreck.
I have no idea how this could be resolved statistically.
[Response: Here’s one way: the re-insurance giant Swiss Re keeps similar data over more than just the USA, and their classifications include both weather events (like hurricanes) and non-weather geophysical events (like earthquakes). Both of course are subject to “more stuff to wreck” but guess what? — the increase in weather-disaster damage is strong and overwhelmingly statistically significant, but not for non-weather geophysical damage.]
tamino: I have looked online for that Munich Re data as I would like to have it on file but I cannot find the original source for your statement. Do you have it? Thanks.
[Response: I don’t, but I did at one time digitize one of their graphs.
]
Even without the Swiss RE earthquake v. weather comparison, one would hope* that with better technology we’d be building more resilient infrastructure, such that, in the absence of changes in event frequency, the increase in damage would be expected to be smaller than the increase in amount of stuff exposed.
*Not that we are always great about resilience even to expected events, much less events that change due to more intense storms with more rainfall and higher storm surge due to higher sea level.
Chris: I have heard that claim many times about the increase in population, not just in the U.S. but globally, and/or the claim that disasters are more likely to be reported now than in the past due to increased media coverage. The response below your post is a very good counterargument, using geological natural disasters as a control group and comparing. It is analogous to the claim that bicycle helmets save lives on a population scale by comparing helmet wearing frequency with cyclist deaths and noting they both drop over time, but then it is pointed out that pedestrian deaths also decrease at a similar rate.