In the southernmost reaches of Burma (Myanmar), along the border with Thailand, lies the Mergui Archipelago. The archipelago in the Andaman Sea is made up of more than 800 islands surrounded by extensive coral reefs.

Working Group:
Coastal Defenses

Built levees, sea walls, and artificial barrier islands can be overcome by just one environmental event. However, mangroves, coral reefs and wetlands have been shown to protect lives and property. This Working Group explores how conserving and restoring coastal habitats can help protect coastal communities and livelihoods from the impacts of extreme environmental events.

Photo: NASA Earth Observatory | More Info
Photo: Duncan

Working Group Summary

Can Nature Help Reduce Our Risk from Coastal Hazards?

Surges from storms, hurricanes and cyclones. Sea-level rise, driven by climate change. Erosion of shorelines and homes. Hundreds of millions of people who live along the world’s coastlines are increasingly vulnerable to these and other natural hazards. Are sea walls and other costly engineered barriers — which can also further degrade coastal ecosystems — the only lines of defense? Or can nature play a cost-effective role in reducing the risk to people and property? The SNAPP Coastal Defenses Working Group is exploring how conserving existing coastal habitats, restoring what has been lost, and deploying innovative hybrid solutions can help protect coastal communities from the impacts of storms and other extreme environmental events. Learn about the Challenge

Photo: NASA/NOAA GOES Project

The Challenge

The World’s Coastlines: Rapid Change and Growing Risk

The world’s coastal zones are changing rapidly — and their rate of change is predicted to increase from coastal development and climate change, both of which will dramatically increase risks of catastrophic damage to coastal communities. In 2011, insured losses from natural disasters (especially coastal and riverine hazards) reached an all-time high, and impacts will continue to worsen with continued climate change.

In fact, the top 15 nations most at risk to natural hazards such as floods, fires and earthquakes are all coastal, tropical and developing countries (World Risk Report 2012). Erosion, inundation and extreme weather events already affect hundreds of millions of vulnerable people, important infrastructure, tourism, and trade — with significant losses to national economies and major impacts on human suffering. And ecosystem degradation raises these risks by further exposing communities and assets to more waves, winds and water.

Coastal and marine habitats — particularly coral reefs and wetlands — are at the front line of many of these changes, and are increasingly lost and degraded. Global losses of coastal habitats are as high as 85% for oyster reefs, 30-50% for wetlands, and approximately 30% for coral reefs. Often, the loss of these habitats is greatest around population centers — maximizing the loss of benefits to people.

Billions of dollars — from international agencies as well as national and local governments — are moving to reduce risks from coastal hazards and climate change, creating both threats and opportunities for natural systems. But most these funds are destined for the creation of “grey infrastructure” such as seawalls, which will further degrade coastal ecosystems, and may not be cost effective for risk reduction when compared to more natural and hybrid alternatives. Because of the wave of global science following Hurricane Katrina and the 2004 Indian Ocean tsunami, decision-makers now recognize that coastal habitats have some role to play in risk reduction.

Those decision-makers are rightly asking:

  • How cost-effective are natural ecosystems for coastal defense?
  • Where and how should we restore these natural defenses?
  • How do we create incentives to reduce risks by conserving coastal habitats?

Read about this Inquiry

The east side of Alligator River National Wildlife Refuge on Pamlico Sound is ground zero for the Climate Change Adaptation Project. Artificial oyster reefs are being installed just offshore, and water control structures are being added to prevent salt water from shooting straight up the canal into the heart of the refuge.

The Inquiry

Natural Defenses: Aims and Products of the Working Group

The Coastal Defenses Working Group — drawing on leaders from engineering, ecology, economics, and development policy — is moving quickly to address the above challenges. Within 24 months of inception, it will:

  • Provide evidence on when, where and how investments in natural defenses are cost-effective;
  • Develop practical guidance and tools for decision-makers and practitioners to implement solutions; and
  • Identify policy and financial incentives that lead to reduced risks for people and nature.

To enhance the pathways to impact and opportunities for practical implementation of its findings, the Working Group will convene a Resource User Group to test and provide feedback for its research insights and the resources it develops. It will also form a Recovery & Restoration Team to help policymakers use the Group’s findings and recommendations in the wake of coastal disasters. Meet the Coastal Defenses Team

Photo: U.S. Fish and Wildlife Service Headquarters | More Info

The Team

The Coastal Defenses Team

Recent Publications by Working Group Members

Papers & Reports

Coastal Wetlands and Flood Damage Reduction: Using Risk Industry-based Models to Assess Natural Defenses in the Northeastern USA. Narayan, S., Beck, M.W., Wilson, P., Thomas, C., Guerrero, A., Shepard, C., Reguero, B.G., Franco, G., Ingram, C.J., Trespalacios, D. 2016. Lloyd’s Tercentenary Research Foundation, London.

Managing coasts with natural solutions : guidelines for measuring and valuing the coastal protection services of mangroves and coral reefs. Beck, M.W. and G-M Lange (Editors); Wealth Accounting and the Valuation of Ecosystem Services Partnership (WAVES). 2016. Waves technical paper. Washington, D.C. : World Bank Group.

Coasts at Risk: An Assessment of Coastal Risks and the Role of Environmental Solutions. Edited by M. Beck. University of Rhode Island (Narragansett).

Guidelines for Coastal and Marine Ecosystem Accounting: Incorporating the Protective Service Values of Coral Reefs and Mangroves in National Wealth Accounts

The effectiveness of coral reefs for coastal hazard risk reduction. Ferrario, F., M. W. Beck, and others. 2014. Nature Communications 5,3794: 1-9.

Damming deltas: A practice of the past? Towards nature-based flood defenses. van Wesenbeeck, B.K., and others. 2014.Estuarine, Coastal and Shelf Science 140, 1-6.

The role of coastal plant communities for climate change mitigation and adaptation. Duarte, C., Losada, I., and others. 2013. Nature Climate Change 3, 961-968.

Coastal Ecosystems: A Critical Element of Risk Reduction. Spalding, M.D., Beck, M. W., van Wesenbeeck, B.K., and others. 2014. Conservation Letters 7(3), 293-301.

Coastal risks, nature-based defenses and the economics of adaptation: an application in the Gulf of Mexico. B. Reguero, D. Bresch, M. W. Beck, J. Calil & I. Meliane. 2014. Proc Int Coastal Engineering.


Coastal Defenses: Advisory Group

The Advisory Group members are specialty advisers to the Coastal Defenses Working Group and contribute to discussions regarding the Working Group’s questions, analyses, and results to help ensure the outcomes most effectively meet the needs of stakeholders and relevant decision makers.

Eron Blomgarden, EkoAsset Partners

Dr. David Bresch, Swiss Re

Dr. Todd Bridges, US Army Corp of Engineers

Christina Chan, U.S. State Department

Dr. Guillermo Franco, Guy Carpenter & Company, LLC

Dr. Nigel Pontee, CH2M HILL

Dr. Mary Ruckelshaus, Natural Capital Project, Stanford University

Dr. Cristina Rumbaitis del Rio, The Rockefeller Foundation

Photo: © Erika Nortemann