How DARPA is Pursuing Nature-Based Solutions around the World

Seventeen hundred U.S. Department of Defense (DoD) bases around the world are subject to sea level rise, which has increased by seven to eight inches since 1900. Natural hazards, such as severe storms and hurricanes, are occurring more frequently; and climate change is changing the profile of those hazards. Innovative solutions are needed to protect these bases. In this episode we’re talking with Dr. Todd Bridges, Senior Research Scientist for Environmental Science with the U.S. Army Corps of Engineers and National Lead for Engineering With Nature®, and Lori Adornato, Program Manager at DARPA, the Defense Advanced Research Projects Agency, about the passion they share for oceanography and for solving future challenges by using innovative nature-based solutions.   Ensuring that DoD installations are resilient in the face of a broad range of natural hazards is critical and demands innovative, outside-the-box solutions. As Lori explains, numerous DoD installations around the world have “gray infrastructure,” bulkheads or seawalls made out of cement blocks that are placed in the water. These require considerable maintenance and can actually create additional problems like changes in the way water and sediments flow that can compromise both habitats and the structural integrity of structures and shorelines. Sustainable solutions are needed for coastal erosion, storm, and flood risks. Natural systems have been supporting such functions for millennia, including coral reefs in the tropics and oyster reefs in sub-tropical areas.   DARPA is investing in leveraging nature to support mission resilience by establishing the REEFENSE program (a combination of “reef” and “defense”), which Lori manages, to take advantage of the natural functions that reefs provide. REEFENSE isn’t a restoration effort. It is an initiative focused on building new, living reef structures through a combination of an engineered base structure, the “building power” the oysters and coral organisms provide, and the beneficial organisms that help to maintain the health of the reef – a nature-based combination that attenuates wave energy and protects shorelines. The goal is to support nature-based ecosystems that can sustain themselves naturally and grow and strengthen over time as calcium carbonate from the oyster shells and coral skeletons is deposited. As Lori explains, this allows the reef to keep pace with sea level rise following the same dynamic that you would find in a normal healthy reef ecosystem.   One of the challenges of this approach is using reef builders that can adapt to the rapid changes associated with climate change, particularly the rise in ocean temperature, which can cause coral bleaching and kill the coral. One way to address this is through adaptive biology, selecting organisms that can better withstand the temperature rise to help the reef system survive.   “It's fascinating, exciting, and inspiring for an agency like DARPA that’s known for ‘gee whiz’ technology to be doing research like this,” notes Todd. “It’s truly engineering with nature. Our EWN team is super excited about working with DARPA on this program, bringing these proposed structures into our laboratories to evaluate them and get at their engineering performance as they transition to deployment in the field.”   It is estimated that the U.S. already derives a flood risk reduction benefit of $1.8 billion annually from existing reefs. In some highly developed coastline areas like Florida and Hawaii, annual benefits exceed $10 million per kilometer of reef. These benefits were discussed in previous EWN podcasts, including Season 1, Episode 3, with Brigadier General Patrice Melancon and Season 1, Episode 6,