The findings, published in the journal Proceedings of the National Academy of Sciences, shed light on the ongoing debate on how climate change has impacted growing costs of flooding and the heightened risk homeowners, builders, banks and insurers face as global temperatures continue to rise.
The losses resulting from worsening extreme rains comprise nearly one-third of the total financial cost from flooding in the U.S. between 1988 and 2017, according to the report, which analyzed climate and socioeconomic data in order to quantify the relationship between changing historical rainfall trends and historical flood costs.
Researchers found that global warming played a significant role in the rise in flood costs in the U.S. and warned that passing warming levels outlined in the global Paris Climate Accord will worsen extreme disaster events. The pact aims to keep the increase in global temperatures well below 2 degrees Celsius, or 3.6 degrees Fahrenheit, compared with preindustrial levels.
A record number of hurricanes, wildfires and floods cost the world $210 billion in damage last year, according to a recent report by reinsurance company Munich Re. The six most expensive disasters of 2020 occurred in the U.S., the worst of which was Hurricane Laura in August.
Even in states where long-term rainfall hasn’t changed, the wettest storms have intensified and caused more financial damage as a result, according to the report.
“Accurately and comprehensively tallying the past and future costs of climate change is key to making good policy decisions,” Marshall Burke, associate professor of Earth system science at Stanford and a study co-author, said in a statement.
“This work shows that past climate change has already cost the U.S. economy billions of dollars, just due to flood damages alone,” Burke said.
Across the country, millions of people are exposed to flood risk. More than 14 million properties are susceptible to flood damage, according to data from First Street Foundation, a nonprofit research and technology group.
However, many homeowners in high-risk areas still don’t have flood insurance because federal flood maps that guide insurance demand are often outdated and fail to factor in the impacts of climate change and intense rainfall. And minority communities in the U.S. tend to have a larger undisclosed flood risk.
Researchers hope their analysis will help assess the costs of other climate change-fueled disasters and result in better climate adaptation strategies across the country.
“The framework that we developed provides an objective basis for estimating what it will cost to adapt to continued climate change and the economic value of avoiding higher levels of global warming in the future,” Noah Diffenbaugh, a Stanford climate scientist and senior author of the study, said in a statement.