Posted on September 9, 2021
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Climate change may raise waters and more Americans than ever live in floodplains, but technology and infrastructure protect them.
Though the images of abandoned cars in waterlogged East Coast streets might make you think otherwise, the relative toll that floods take on the U.S.—in property and lives—has decreased over time. Flooding costs as a share of gross domestic product declined almost 10-fold since 1903 to 0.05% of GDP, while annual flood death risk—fatalities per million—dropped almost threefold. World-wide data are sparser, but flood research shows costs relative to GDP and deaths relative to population have decreased globally from 1980 to 2010.
Scary headlines about rising flood costs tend to come from misleading statistics of total damages, which say more about U.S. economic growth than they do about climate change. Since the start of the 20th century, the U.S. population has quadrupled and annual GDP has increased 36-fold. There are more people and structures in the U.S. than ever—including in floodplains. A flood that hits, say, Atlanta, will encounter far more people and buildings today than 30 years ago. The number of exposed housing units in the city’s floodplain went up by 58% from 1990 to 2010. At the same time, greater wealth and better technology have made people and property in low-lying areas safer from floods. Only when you look at damages in the context of GDP can you filter out what’s a sign of growing wealth and what indicates flood resiliency or vulnerability.
Though it hasn’t been well publicized, the U.N. Intergovernmental Panel on Climate Change says it has “low confidence in the human influence on the changes in high river flows on the global scale.” It expects more areas will see the frequency of floods go up than go down—a negative impact of climate change, but one that’s much less dramatic than media coverage might suggest. And as the world grows richer, infrastructure and technology are likely to drive down relative flooding costs and deaths. The data show they already are.
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