Climate Expert: U.S. Flood Damage As Percent Of GDP Decreased 90% Since 1940

Everything is getting worse, right? Flooding especially. NPR tells us that:

[H]eavier rainstorms driven by global warming are sending more water into residential neighborhoods from the Gulf Coast to New England to Appalachia to the Pacific Northwest.

A Federal Emergency Management Official official explained to The Washington Post:

We know that as climate changes, the impacts are getting worse. We’re seeing more and more flooding going on as a result.

Everybody knows this — it is conventional wisdom. [emphasis, links added]

Not only is the conventional wisdom on flooding wrong, but data show that flood impacts as measured by direct economic losses have actually decreased by about 90% since 1940 as a proportion of U.S. GDP.

The United States is, in fact, more resilient to flooding than it has ever been.

The reduction in flood impacts is an incredible story of success sitting out in plain sight that is completely ignored, in favor of stories that instead tell us that down is up.

The figure below shows U.S. annual flood damage as a proportion of GDP. In 1940 flood losses amounted to a 2023 equivalent of about $50 billion per year, and in 2022 they totaled about $5 billion, a reduction of over 90%.

The figure below shows annual losses adjusted only for inflation over the same period.

Over course, aggregate flood loss totals have increased — from 1940 to 2023 the U.S. population increased from about 130 million to over 330 million. Over that same period, U.S. GDP increased by more than 10x.

The math is simple: flood damage in constant dollars increased by about 3x (figure above) while GDP increased by more than 10x — that means that flood damage has dropped dramatically as a proportion of economic activity.

A word of caution — none of this tells us anything about the climate. If you want to explore climate trends, look at climate data, not economic loss data.

But it does tell us that those promoting trends in economic impacts of floods and other extremes as evidence of human-caused changes in climate are peddling misinformation.

What the most recent science assessments say about changes in extreme precipitation and flooding may be surprising.

For instance, the most recent National Climate Assessment (NCA) concludes (emphasis added):

The complex mix of processes complicates the formal attribution of observed flooding trends to anthropogenic climate change and suggests that additional scientific rigor is needed in flood attribution studies. As noted above, precipitation increases have been found to strongly influence changes in flood statistics.

However, in U.S. regions, no formal attribution of precipitation changes to anthropogenic forcing has been made so far, so indirect attribution of flooding changes is not possible. Hence, no formal attribution of observed flooding changes to anthropogenic forcing has been claimed.

Research published since the most recent NCA supports its conclusions (e.g., here and here). The lack of trends in flooding holds globally as well.

Because there is no evidence of a nationwide decline in flooding (just as there is no evidence for an increase), the dramatic reduction in flood losses as a proportion of economic activity must be the result of overall better collective decisions about where to build and how to manage floodplains.

It is apparently easy to confuse readily available social media postings showing flooding — which of course continues to occur — with the hyperbole of “America Underwater,” as The Washington Post put it.

Recent flood events in New York City and elsewhere show that there is still a lot of work to do to continue to improve the nation’s resiliency to floods.

Roger Pielke Jr. has been a professor at the University of Colorado since 2001. Previously, he was a staff scientist in the Environmental and Societal Impacts Group of the National Center for Atmospheric Research. He has degrees in mathematics, public policy, and political science, and is the author of numerous books. (Amazon).

Read rest at The Honest Broker

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