The graph above is an update from a version I first showed in Congressional testimony in 2013 (PDF). It shows US flood damage (as recorded by the NWS in 2013 $) as a proportion of US GDP (as recorded by the OMB, also in 2013 $, Table 10.1 here). The graph starts in 1940 because this is the start of the OMB GDP dataset.
The US is prone to very large flood events, resulting in tens of billions of dollars in losses. However, the trend since 1940 is striking. As the nation has seen its economic activity expand by a factor of almost 13, flood losses as a proportion of that activity have dropped by about 75%.
Please don’t use this data to say anything about the incidence of flooding in the US or changes in climate. For that, I urge you to look at data and research, discussed here. You’ll find very little evidence of increasing flood frequency or magnitude either in the US or globally. Regardless, the diminishing economic impact of floods in the US is undeniable.
The Climate Fix 
Reblogged this on I Didn't Ask To Be a Blog.
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I don’t think comparing agricultural flood losses to GDP is very instructive. The proportion of income spent on food declines as productivity increases. So the graph (I think) says more about productivity gains than anything about flooding or flood mitigation.
Consider a case where every year 20% of agriculture was lost to flooding — with no trend either way. The percentage of GDP lost to agricultural flooding would still decrease. The graph would probably look very similar to the one you posted.
A quick Google found a random graph that claims to show agriculture as a percent of GDP in the US over time. I make no claims to the quality of the data, but my guess is that it is representative: http://i.bullfax.com/imgs/3c09f51195ac4942fb8ab21ae27049d399796a79.jpg
I think it would be instructive to see the flood damage as a percent of agricultural output.
Thanks,
tim
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I think it would be instructive to see the flood damage as a percent of agricultural output.
How would that help, if most of the damage is non-agricultural?
Generally floods spoil a single crop, not even spoiling the land it is on, whereas infrastructure can be set back decades as roads and (very expensive) bridges are washed away.
To take a counter example. If we took losses as a percentage of the urban infrastructure, the decline is probably steeper (as over the period of the data there has been massive industrialisation and urbanisation).
GDP is a way to allow for the fact that the economy has changed.
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Hello, Dr Pielke. I messaged you on Twitter as well… have you updated your US Flood Damage as Proportion of GDP slide? Thank you, Dan (12/2/2106)
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