Is this really climate related? My initial suspicion is that as technology advances, we just have more complicated (expensive) systems and infrastructure that are harder to repair because of the expertise required. We also become more and more reliant on technology every day, but also more and more incompetent when that technology suddenly fails. It is sort of a 'house of cards' effect.
Whereas we definitely have more sensitive equipment inside a given building, we also have improved materials and designs that can better-withstand weather events.
I wonder to what degree events that would have formerly been billion-dollar disasters have dropped off this chart, because power plants, hospitals, etc are resisting forces that would have seriously damaged older buildings.
And on the other side, I wonder to what degree our lax infrastructure spending has exacerbated the cost of these disasters. Truly if we were spending on levees and spillways at engineer-recommendations, recent hurricanes and floods would have caused notably less damage [1].
I guess my only point is that while I concur that it's careless to try to draw conclusions from this data, I don't think we can clearly assume that progress alone shows us which direction the data is skewed and why.
[1] Would we have even had to open the Morganza spillway if Louisiana's levees had been maintained and updated over the years?
The part I found most interesting was the points-of-origin graph, and how closely that correlates with the Tropic of Cancer. But, there's also a historical graph there for your edification.
The historical graph here does not appear to show any upward trend 1950 to present for frequency of EF3-EF5 tornadoes; if anything, they may be becoming slightly less common.
In their report, they found no long term trend for drought conditions. I can find nothing that casts doubt on their research.
If I were serious about figuring out whether the cost figures for natural disasters were attributable primarily to increased costs or primarily to increased severity of natural disasters, I'd use earthquakes as a comparison -- if it's an increase-of-cost issue, then I'd expect to see the same increase-of-cost for historical earthquakes. If the increase-of-cost for earthquakes is substantially less than of the natural disasters in this report, then I'd be inclined to attribute it to a greater frequency and severity of natural disasters.
* If I were serious about figuring out whether the cost figures for natural disasters were attributable primarily to increased costs or primarily to increased severity of natural disasters, I'd use earthquakes as a comparison -- if it's an increase-of-cost issue, then I'd expect to see the same increase-of-cost for historical earthquakes. If the increase-of-cost for earthquakes is substantially less than of the natural disasters in this report, then I'd be inclined to attribute it to a greater frequency and severity of natural disasters.*
On the other hand, we've got a lot better at building earthquake-resistant structures.
Also, the number of earthquakes causing any significant damage in the United States over the past two hundred years is small enough to be statistically iffy.
