As the planet warms, the severity and frequency of hurricanes is increasing—and with it, economic losses from storm surge–related flooding. A new paper, published earlier this month in the journal Natural Hazards Review, assesses the impacts of rising seas and wetland change on storm surge flooding in a region expected to be a “hot spot” for sea level rise—the Chesapeake Bay.
The study results suggest that, particularly for strong storms in the future, the combination of wetland loss and sea level rise spurs significantly more property damage and affects more people than sea level rise alone.
“In low-elevation communities, even a small change in sea level can have a big impact,” said Margaret Walls, study coauthor and senior fellow at Resources for the Future (RFF). “Wetlands provide an important buffer to storm surge. In combination, wetland loss and sea level rise can create, almost literally, conditions for a perfect storm. This has serious repercussions for insurance markets, developers, and people living in this highly populated region.”
To quantify damages, the study authors model two historic hurricanes that hit the Chesapeake Bay region at the turn of the century: a relatively weak storm—Hurricane Dennis, in 1999—and a relatively strong storm—Hurricane Isabel, in 2003. By running computer simulations of these storms, in combination with coastal land use change tools from the National Ocean and Atmospheric Administration (NOAA), the team could model the combined and isolated impacts of sea level rise and wetland loss on coastal flooding in 2100.
They came to the following conclusions:
- Under maximum sea level rise scenarios, even relatively weak storms in 2100 are projected to have a greater impact on the Chesapeake Bay region than high-intensity storms today.
- The loss of wetlands significantly increases the amount of flooding in the region during strong storms—flooded area increases by a factor of 3.6–6.0 compared to current conditions. Without considering wetland loss, flooded area increases by a factor of 1.3–2.3.
- In a scenario in which wetland loss is considered alongside sea level rise, a strong storm could put 789,000–1,971,000 people at risk of coastal inundation in the future.
- Wetland loss combined with sea level rise would create $2.5 billion–$13 billion in property damage during a strong storm in 2100.
Notably, the modeling also shows that Virginia is likely to lose more wetlands than Maryland. However, Anne Arundel County, Maryland—which is located between Washington, DC, and Baltimore—has the highest number of people at risk from coastal flooding.
“The results show that coastal communities should be braced for a future marked by climate change and sea level rise,” Walls said. “Hopefully, our research will support efforts to develop adaptation measures that include conservation, restoration, and floodplain management measures. Natural infrastructure can go a long way to protect us in an uncertain future.”