Mangroves are weeds; if you give them half a chance they grow in some of the most inhospitable environments; with their knees in seawater and their trunks in the air. They create forested barriers between the wrath of the seas and our coastal communities providing benefits in coastal defense and fisheries. Unfortunately there are too many examples where we have not given mangroves half a chance; hundreds of thousands of hectares have been lost to pollution, aquaculture and other developments. These represent real losses to the coastal communities – often some of the most vulnerable communities living in the highest risk areas.
Why does this happen? It happens in part because the economic value of the benefits from mangroves and other habitats are not measured in terms relevant to Ministries of Finance, Development, and others and thus discounted in policy and management decisions.
But fortunately this is a problem that can be solved. The Philippines is a country that recognizes that mangroves forest can provide real benefits in risk reduction to people and property – the big questions were when and where do they provide these benefits and how valuable are they.
Last year, the World Bank WAVES program in partnership with The Nature Conservancy and others published Guidelines on how to rigorously value these coastal protection benefits to be considered in national accounting and other management decisions. Over the past year, we have worked closely with the Philippines government to assess the value of mangroves nationally using these approaches.
The Philippines is among the most vulnerable countries in the world to flood damage from typhoons and extreme events: Typhoon Haiyan alone caused more than 6,000 deaths and over US $2 billion in damages. Between 2005 to 2015, 56% of property damage in the Philippines was due to typhoons and storms, and another 29% due to floods. These impacts underlie why decision-makers are looking for effective and cost effective approaches for flood risk reduction.
Mangroves can protect coastlines by decreasing the risk of flooding and erosion. Mangroves also support livelihoods and reduce social vulnerability by providing resources such as fish.
Yet mangroves continue to be lost at alarming rates. For example, 19% of the world’s mangroves were lost between 1980-2005. In the Philippines, mangrove loss has occurred primarily due to conversion of land to other uses, including aquaculture and development.
Our team, led by The Nature Conservancy and IH Cantabria, worked with the WAVES program to identify where mangroves provide the greatest protection benefits; the results are available in a Technical Report and summarized in a Policy Note. Using high-resolution, probabilistic flooding models, we compared flooding for scenarios with and without mangroves and estimates the expected benefits of mangroves for protecting people and property in social and economic terms. Without mangroves, flooding and damages to people, property and infrastructure would increase annually by approximately 25%. Across the Philippines, mangroves reduce flooding to 613,000 people annually, of whom more than 23% live below poverty, and avert more than US $1 billion in damages to residential and industrial property. If mangroves were restored to their 1950 distribution, there would be additional benefits to 267,000 people annually, including 61,000 people below poverty, and US $450 million in annual averted damages. Mangroves provide the most significant benefits for the most frequent storms (e.g., the 1 in 10 year storm) but even for extreme, 1-in-50 year events, mangroves avert more than US $1.7 billion in damages (Figure 2 below).
This work shows that the protection benefits of mangroves and other coastal habitats can be measured and valued, and that these benefits are incredibly important. Mangrove conservation and restoration can reduce coastal flood risks and this work identifies where mangroves provide the greatest benefits to the people of the Philippines.
These results can also be considered in risk industry models in the Philippines and in the development of innovative finance mechanisms such as catastrophic hazard and resilience bonds to support mangrove restoration.
By valuing these coastal protection benefits in terms used by finance and development decision-makers (e.g., annual expected benefits), these results can be readily used alongside common metrics of national economic accounting, and can inform risk reduction, development and environmental conservation decisions in the Philippines. Globally, this work can inform the development of national accounts for natural capital, which can ensure that these ecosystem services are valued and accounted for in policy and management decisions.