Building resiliency in the face of a rising sea: How coastal communities can learn from nature

By Jacques Chirazi

Climate change is one of the biggest challenges the world has ever faced. Flooding, storm surge, and sea level rise are serious threats to natural resources, infrastructure, and human communities in coastal areas. In an effort to adapt to these changing conditions, planners and policymakers should consider nature’s strategies when developing coastal resiliency plans to protect communities from increasing coastal erosion and flooding due to rising sea levels. For example, green infrastructure like wetlands and sand dunes can be used to break up the waves and reduce their speed, reducing the waves’ erosive power. These approaches can also limit the area which waves can reach, preventing flooding.

The Problem

The recent Paris agreement sets out a global action plan to put the world on track to avoid dangerous climate change by limiting global warming to below 2°C. However, given the high concentration of carbon dioxide already in the atmosphere, the climate will continue to change (see Figure 1), impacting both human communities and the environment.

Since 1870, global sea level has risen by about 7.5 inches. Estimates of future sea level rise vary for different regions, but studies project global sea level to rise by another 1 to 4 feet by 2100, with an uncertainty range of 0.66 to 6.6 feet.  It is now widely accepted that the world’s coastlines and coastal cities will be faced with seas that are rising faster than ever experienced. In California, we are very likely to experience a sea level rise of 16 inches by 2050 and 55 inches (1.4 meters) by 2100.

Sea Level Rise Adaptation & Mitigation Strategies

The potential impacts from sea level rise to the state of California’s economy and infrastructure include projected impacts on coastal agriculture, the fishing and aquaculture industry, tourism, ports, roads and bridges, and water and power infrastructure. Public agencies need to develop and implement viable adaptations plans to mitigate climate change impacts. California water agencies will have to deal with changes in flow, facilities at risk, and saltwater intrusion into intake systems. Airports and ports will have to contend with shoreline infrastructure that is not at the right sea elevation. For example, the ports of Los Angeles and Long Beach are vulnerable to significant flooding from sea-level rise. Given that these two ports handle about 50% of the containers shipped into the United States, the rise could disturb the efficiency of goods movement, resulting in serious economic implications for California and the country. Transit and transportation agencies will be faced with roads, railways, and subways vulnerable to flooding. Parks, planning agencies, and coastal cities will have to tackle the issue of  floodwater in industrial and residential communities, especially in those areas that are least prepared to cope with these new risks, such as disadvantaged communities.

Ultimately, it is going to be up to local governments to ensure that their communities adapt to this new reality. Most local governments in California have what is called a local coastal plan (LCP), which sets ground rules for land use in coastal zones, as described by state law. These plans are certified by the California Coastal Commission (CCC), which has planning, regulatory, and permitting responsibilities, in partnership with local governments (60 cities and 15 counties), over all development taking place within California’s 1,100-mile coastal zone.  About 90 percent of the state’s coastal zone falls into an LCP. However, most of these plans were developed in the 1980s, before potential sea level rise became a growing concern for coastal communities, and there is no legal requirement for them to be updated.