Encroaching Tides: How Sea Level Rise and Tidal Flooding Threaten U.S. East and Gulf Coast Communities over the Next 30 Years

Cambridge: Union of Concerned Scientists.This recent study examined coastal flooding along the Eastern and Gulf coasts of the US, and did not include the Great Lakes. However, the report concludes that extreme weather events and floods are occurring nationwide, and that other coastal communities are also at higher risk. Coastal communities and states, and the nation as a whole, need to prepare for near-term changes in tidal flooding, while working hard to minimize longer-term losses through efforts to both adapt to these changes and limit their extent. The report outlines steps to ensure more resilient coastal communities, which are extracted and reproduced below. “BUILDING COASTAL RESILIENCE IS A LOCAL IMPERATIVE . . . Over the next few decades—the time frame of our analysis—changes set in motion by our past and present heat-trapping emissions will largely drive the pace of sea level rise. The lag of several decades between the release of carbon into the atmosphere and the response of the ocean means that more tidal flooding is virtually guaranteed, and that communities need to act with urgency. Locally, there are many things we can do to help ensure enduring coastal communities, including: • Upgrade the built infrastructure in harm’s way. With help, communities can prioritize and incentivize flood-proofing of homes, neighborhoods, and key infrastructure, such as sewer and stormwater systems. • Avoid putting anything new in harm’s way. Communities can use a range of regulatory and planning tools to curtail new development in coastal locations subject to tidal flooding now and in the future. • Consider the risks and benefits of adaptation measures. Some measures to limit the impact of coastal flooding can provide multiple benefits, while others can alter shoreline dynamics and damage neighboring areas and ecosystems. Decision makers need to ensure that a rush to protect coastal communities builds broad-based resilience, rather than helping some areas while putting others at risk. • Develop a long-term vision. Communities that create a vision for both near-term protection and long-term resilience in the face of sea level rise—and craft plans for building better, safer, and more equitably—will be best positioned to thrive in the years ahead. . . . AND A NATIONAL ONE But local communities can’t go it alone—coastal challenges are too great, the costs are too steep, and too many people are at risk. Instead, we need a coordinated, well-funded national response to our country’s coastal vulnerability involving federal, state, and local collaboration. Federal and state governments can help build local resilience by supporting, incentivizing, regulating, and even mandating action. They can: • Build and maintain a coastal monitoring and data-sharing system equal to the threat. Key federal agencies can sustain and expand efforts to monitor and project sea level rise and flooding, and ensure that local decision makers have access to the data. • Encourage or mandate the use of good scientific information. Agencies can require that communities and other applicants for state and federal funds use the best available data, and demonstrate that new development and redevelopment projects can withstand projected tidal flooding and storm surges. • Support planning. More federal support for state and local planning and collaboration can accelerate efforts to build coastal resilience. • Mobilize funding. Adapting to sea level rise will require major, sustained investment. Federal policy makers need to develop new funding sources to support resilience-building efforts at the state and local level. • Improve risk management. The true costs of living on the coast are not reflected in the price of flood insurance and other risk management tools. But big increases in the cost of insurance are hard for many to bear. Federal incentives to reduce some property owners’ risks and costs can aid the transition to a more solvent flood insurance system and better risk management. • Ensure equitable investments. Federal investments in coastal resilience can prioritize households and communities with the greatest needs. • Reduce heat-trapping emissions. A near-term increase in sea level rise and tidal flooding may be locked in, but changes later this century and beyond are not fixed. To slow the rate of sea level rise—and enable coastal communities to adapt in affordable and manageable ways— we must reduce our global warming emissions.