A recent Stanford study found that climate change caused one-third of the flood damage over the past thirty years in the United States. Increased rainfall due to warmer weather caused nearly $ 75 billion of the estimated $ 199 billion. This devastation occurred from 1988 to 2017.
The researchers published their research on January 11, 2021, in the journal
The goal of the flood damage study
This study helps resolve an ongoing debate about the growing financial burden of floods due to climate change. It also sheds light on the total financial costs of global warming.
Lead author Frances Davenport, Ph.D. A student at Stanford’s School of Earth, Energy, and Environmental Sciences said:
“It is well known that extreme rainfall has increased and is likely to increase in the future. But it’s not clear what effect that has had on financial damage. Our analysis allows us to isolate how much of those changes in precipitation translate into changes in the cost of flooding, both now and in the future. “
However, until recently, scientists weren’t sure whether climate change contributes to rising flood costs. And they wondered, if so, how much. Researchers have been debating this issue for decades. We also saw this in the recent climate report from the US government and the IPCC.
At the center of the debate is whether the costly floods were primarily due to socioeconomic factors. These include an increase in population, housing development, and increasing property values. Much of the previous research focused primarily on detailed case studies of specific disasters or long-term changes in certain states. Some of the research also addressed the correlations between increased rainfall and flood damage across the United States.
How Scientists Showed Climate Change Is Causing Increasing Flood Damage
To test their theory, the scientists started with higher resolution climate and socioeconomic observations. They then applied advanced economic techniques to understand the correlation between historical variation in rainfalls and flood costs. In addition to this, they used statistical calculations and climate science to understand the relationship between increased rainfall and the costs of flooding.
Their in-depth analysis found that climate change has contributed significantly to the increase flood costs In the US In addition, scientists believe that continued global warming will lead to more cases of these extreme floods. Unless all the United Nations Paris Agreement countries agree to cut emissions, floods will likely only increase in severity and frequency.
“Previous studies have looked at pieces of this puzzle, but this is the first study that combines a rigorous economic analysis of the historical relationships between climate and flood costs with really careful extreme event analysis in both historical observations and climate models. global, across the United States. “Said lead author and climate scientist Noah Diffenbaugh, a professor at the Kara J. Foundation at Stanford Earth.
“By putting all of those pieces together, this framework provides a novel quantification of not only how much historical changes in precipitation have contributed to flood costs, but also how greenhouse gases influence the types of precipitation events that they cause the most damaging floods ”.
Scientists compare their analysis with other cause and effect scenarios. For example, they saw how raising the minimum wage would affect employment. Or how the addition or subtraction of a specific player contributes to the victories of a basketball team, for example.
In their study, the research team developed an economic model based on observed precipitation and monthly flood damage cases. Then, they controlled for other factors that could affect flood costs, such as rising home values. They then calculated the variation in precipitation intensification over the 30-year study period. Finally, they calculated the economic cost if the fluctuations in rainfall had not occurred.
“This counterfactual analysis is similar to calculating how many games the Los Angeles Lakers would have won, with and without the addition of LeBron James, holding all other players constant,” said study co-author and economist Marshall Burke, an associate professor at Earth. systems science.
Implications of this study for the future of climate change research
After completing these calculations, the research team concluded that precipitation caused 36% of the flood costs from 1988 to 2017. To reach this conclusion, they totaled the amounts of rainfall in all individual states in the US. They also found that the changes in rainfall were mainly due to increases in extreme flood events. These have been responsible for the majority of flood expenses historically.
“What we found is that, even in states where long-term average precipitation has not changed, in most cases, the wettest events have intensified, increasing the financial damage relative to what would have occurred without them. changes in precipitation, ”he said. Davenport, who received an Interdisciplinary Graduate Scholarship from Stanford in 2020.
The research team takes note of their analysis of the financial costs of climate change It could apply to other natural disasters.
“Getting an accurate and complete account of the past and future costs of climate change is key to making good policy decisions,” Burke said. “This work shows that past climate change has already cost the US economy billions of dollars, just by flood damage alone.”
The team says their economic model could be applied to other natural disasters in the United States and around the world. It can also be used to understand climate impacts in various sectors of the economy. Finally, it could help with cost-benefit analyzes of climate mitigation and adaptation strategies.
“The fact that these results are as robust and definitive as our understanding of the role of historical precipitation changes in the financial costs of flooding really advances,” said Diffenbaugh.
“But more broadly, the framework we developed provides an objective basis for estimating what it will cost to adapt to ongoing climate change and the economic value of avoiding higher levels of global warming in the future.”