New opportunities for our natural coastal infrastructure

Million Dollar coral reefs: more than 325 kilometers of reefs reduce storm damages across the US by more than over $1M/km.

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Five years after the Paris Climate Agreement, 2020 ended as the second warmest year (just behind 2016 according to NOAA) and with the hurricane season in the North Atlantic setting a new record of 30 storms. Natural disasters cost US 2010 billion globally, more than the previous year. Record numbers for natural hazards are a cause for concern because the adaptation gap (i.e. the difference between existing adaptation efforts and adaptation needs) keeps increasing and with mounting economic costs. Yet, both the public and private sector are taking steps to understand and drive climate risk response (for example, in 2020 risk modelers rolled out the first climate change models that extend the industry models to capture near and long-term impacts posed by climate change) as we prepare a green recovery from the global pandemic. I believe that our natural infrastructure (i.e. natural ecosystems and nature-based features that are actively managed for climate resilience benefits) can be an important part of these efforts. 

As a civil and coastal engineer, my work is centered on ocean climate hazards and their impacts. I believe in multidisciplinary and solutions-based science to inform sustainable solutions for the natural and built environment. My research focuses on demonstrating how coastal communities can align resilience and environmental goals by using coastal ecosystems as a natural infrastructure. Most recently, we demonstrated the value of US coral reefs for flood risk reduction.

In a recent article, we showed that it is possible to identify and quantify where ecosystems can prevent flood impacts to the built infrastructure. Across the U.S., coral reefs provide over $1.8 billion annually in flood prevention. By combining climate, hydrodynamic, engineering, economic and geospatial modeling, we quantified how and where the loss of reefs would increase flood damages to people, buildings, economic activity and critical infrastructure (e.g. hospitals, schools, or roads). The role of reefs and other ecosystems in attenuating waves and flooding had been widely acknowledged in the past. Yet, spatial socioeconomic valuation remained challenging given the complexity of these environments, the spatial scales involved, and the precision needed to map flooding at the local level.

However, the distribution of these benefits matters a lot. Many coastlines in Florida and Hawai’i receive annual benefits of over $10 million/km. For example, along the shorelines of Oahu or Miami (see Maps below), specific reef systems concentrate a majority of these benefits. The rigorous assessment of these benefits and such spatial concentration open up new opportunities to better manage this natural infrastructure. 

Million Dollar Reefs. There are more than 325 kilometers of $Million Dollar coral reefs across the US that reduce storm damages by >$1M/km annually. Map developed with J. Kendall and C. Lowrie. 

For example, coastal management approaches (e.g. the ridge to reef approach in islands) could be advanced to incorporate these 'Million Dollar Reefs' in an explicit manner, as specific coastal zone management units, in addition to other geophysical and socioeconomic criteria (for an example see the National Coastal Management Plan in Seychelles developed by the World Bank). Such ‘Reef-lined management zones’ could help maintain reefs' flood risk reduction functions, while also contributing to address their stressors (e.g. runoff). 

Coastal ecosystems need to be conserved for all their benefits they provide to people and nature, but with limited funding for their conservation (mostly from public and philanthropic sources) other innovative funding models are also needed. The value of US reefs for flood protection makes a strong economic case for their maintenance and conservation as natural flood protection. Therefore, these risk reduction benefits allow exploring climate financing mechanisms to align hazard mitigation and environmental goals. One clear example is through insurance mechanisms, as demonstrated in Quintana Roo in Mexico where an insurance policy covers hurricane risk for the Mesoamerican barrier reef along 160 kms of coastline (see the feasibility analysis for parametric insurance for coral reefs in the U.S. based on these results by The Nature Conservancy). 

This research work also showed that we should have a broader discussion about the metrics used to measure risk.  Whereas economic valuations are important (e.g. for hazard mitigation funding from FEMA), our results show that social vulnerability aspects are critical to understand risk. We found that the impacts of losing reefs would disproportionately affect minorities and low-income people in Puerto Rico, American Samoa and USVI (areas still recovering from past hurricanes). As the U.S.  start planning an ambitious infrastructure plan, these social metrics should be considered for prioritizing resilience investments, especially because some of the most vulnerable communities could benefit the most from ecosystem-based adaptation strategies. 

Five years after Paris, I believe there are important global opportunities to be seized for ecosystem-based adaptation and the use of ecosystems as natural infrastructure. As we prepare for a post-pandemic green (and blue) recovery in the context of the Biodiversity Conference of Parties and the UN Climate Change summit (COP26), nature-based sustainable approaches can help us meet both the green growth and the climate resilience agendas. 

Borja Reguero

Associate Research Professor , University of California Santa Cruz

Ocean modeling, coastal hazards, climate resilience, natural infrastructure, climate change adaptation, engineering.