New research published recently in the journal Proceedings of the National Academy of Sciences reports on the economic toll that intensifying flooding from climate change has heaped on the US over the last thirty years. This report from Stanford scientists provides more support for the economic incentives of addressing climate change head-on.
"The fact that extreme precipitation has been increasing and will likely increase in the future is well known, but what effect that has had on financial damages has been uncertain," said lead author Frances Davenport, a PhD student in Earth system science at Stanford's School of Earth, Energy & Environmental Sciences (Stanford Earth). "Our analysis allows us to isolate how much of those changes in precipitation translate to changes in the cost of flooding, both now and in the future."
Davenport and fellow scientists determined that one-third of the financial costs of flooding in the United States from 1988 to 2017 were a result of intensifying precipitation. These costs tallied to nearly $75 billion of the estimated $199 billion in flood damages during that period. The key to obtaining these numbers was being able to isolate the factors contributing to flooding and their associated financial costs.
"Previous studies have analyzed pieces of this puzzle, but this is the first study to combine rigorous economic analysis of the historical relationships between climate and flooding costs with really careful extreme event analyses in both historical observations and global climate models, across the whole United States," said senior author and climate scientist Noah Diffenbaugh, the Kara J. Foundation Professor at Stanford Earth. "By bringing all those pieces together, this framework provides a novel quantification not only of how much historical changes in precipitation have contributed to the costs of flooding, but also how greenhouse gases influence the kinds of precipitation events that cause the most damaging flooding events," Diffenbaugh added.
In order to do this, the researchers designed a cause-and-effect economic model that controlled for factors that could affect flooding costs. Using data on observed precipitation and monthly reports of flood damage, they calculated the change in extreme precipitation in each state as well as the economic damages that would have incurred had not such extreme precipitation occurred.
Co-author Marshall Burke, clearly a basketball fan, comments: "This counterfactual analysis is similar to computing how many games the Los Angeles Lakers would have won, with and without the addition of LeBron James, holding all other players constant.”
The results from their analysis show the importance and urgency of investing in climate change action policies. It also shows the economic value in it. "Accurately and comprehensively tallying the past and future costs of climate change is key to making good policy decisions," concludes Burke. "This work shows that past climate change has already cost the U.S. economy billions of dollars, just due to flood damages alone."