Stopping floods, protecting lives, and saving money? Mangroves do it all for free
By Ashley Marranzino, Marine Biology, University of Rhode Island
The team, led by Dr. Pelayo Menéndez from Spain’s Instituto de Hidráulica Ambiental de la Universidad de Cantabaría, modeled expected flood damages in coastal areas under different scenarios. This is not the first time scientists have tried to place economic value on ecosystem services, or the benefits we derive from the environment. A 2011 estimate put the global value of these ecosystem services at over $125 trillion USD per year.
Dr. Menéndez and the other researchers followed the recommendations of the World Bank to develop a risk-assessment model similar to those commonly used by insurance companies. They evaluated the expected flooding damage for 700,000 km of coastlines in the sub-tropics and tropics both with and without mangroves present. To determine the extent of damage mangroves prevent in an area, they subtracted the expected cost of damages in areas with mangroves from the total cost of damages anticipated if there were no mangroves present.
By modeling the total monetary cost of property damage, the area of land flooded, and the number of people impacted by flooding, the team was able to determine both the social and economic costs associated with mangrove flood protection. And they found that mangroves actively prevented more than $65 billion USD in property damage and protect over 15 million people every year worldwide.
The study estimates that for extreme storms with only a 1% chance of occurring each year – called a 100-year storm – mangroves will avert $270 billion in property damage, prevent nearly 100,000 km2 (24.5 million acres) of land damage, and protect 37 million people and their homes from injury and flood damage. Climate change and warming oceans are expected to increase the intensity and frequency of severe storms, making these “historic” storms more likely and elevating the importance of mangroves.