Not only is California threatened by droughts and heatwaves, but also gradual sea level rise along the state’s coastal regions. In both cases, climate change is largely to blame, and as the planet continues to experience increases in temperature, these impacts are expected to worsen. Here, we examine the current state of sea level rise in California and future projections. 

Between 2020 to 2050, sea levels along the coastlines of the United States are expected to rise between 10-12 inches, with some variance due to regional differences in geography. Along the west coast alone, a rise of four to eight inches is projected, threatening the state of California. While these numbers may seem insignificant, this incremental rise also corresponds with extreme coastal flooding and more severe storm surges which will reach further inland. Predictably, these changes are caused by factors of human activity and climate change, associated with the burning of fossil fuels which creates greenhouse gases. In turn, this warms the atmosphere and melts ice caps and glaciers, causing expansion in ocean water. At current emission levels, by 2100, sea levels are expected to rise by two feet across US coastlines, and a failure to curb emissions effectively would cause an additional 3.5-7 feet of sea level rise.

Higher waters would drown coastal regions, and in the United States, 40% of the population lives within 60 miles of coastlines. Across the Californian coast, flooding of just one foot would cause 15 billion dollars of property damage, and significantly impact the livelihoods of 38,000 people. Low-lying communities along cliffs and beaches are at the most risk of such damages, where erosion and coastal degradation would reduce the amount of livable space. Aside from property, damages to public infrastructure would limit state capacities in providing health, transportation, power generation, waste processing, and water treatment services. Access to natural resources and agricultural supplies are also threatened due to saltwater intrusion within freshwater sources, or toxic contamination from hazardous pollution. Disruptions of access to ports and railways would cause billions in revenue loss for the entire state, severely impacting economic activities.

Thankfully, sea level rise in California is a slow and incremental process, one that can be addressed given the appropriate allocation of time and resources. The California Ocean Protection Council recently published a detailed action plan, outlining a five-year roadmap of agenda items designed to help the state adapt to sea level rise. It includes measures to improve the resilience of coastlines, inland areas, bays, and estuaries against the threats of flooding, erosion, and habitat degradation. In brief, the plan is based upon several principles, taking advantage of scientific knowledge, strategic partnerships and alignment, transparent communications, local involvement, long-term resilience projects, and social equity. 

In practice, the state is already beginning to implement certain resilience measures. For example, the community of Gleason Beach, located on the Sonoma Coast, has been experiencing gradual cliff erosion by one foot a year, which is causing damage to sections of a nearby highway. Under a 26 million dollar project, people, buildings, and infrastructure are being relocated further inland. This process, called managed retreat, also involves accommodation and protection by building flood-resistant buildings, or by installing engineered barriers along beaches and waterways to improve land retention. In addition to man made structures, there are natural barriers that help protect coastlines and beaches from erosion, storm surges, and flooding. 

Coral reefs, aside from providing a healthy ecosystem for marine life, also serve as breakwaters, armoring vulnerable shores from the kinetic energy of wave impacts. Though coral reefs around the world are threatened by warming oceans and sea level rise, in 2020, over 30 acres of new reef habitats were constructed off the coast of southern California, as part of a habitat restoration project. Conversely, mangrove forests, which prevent coastal erosion and reduce the severity of tidal currents, also offer another natural alternative form of coastal protection while serving as valuable carbon sinks. Native to tropical regions, red, black, and white mangroves can be found within wetlands across the Baja California Peninsula. Together, reef restoration and mangrove proliferation can be utilised in conjunction, on top of existing efforts, to aid in protecting coastal regions.

Even if climate change is anthropogenically driven, the solutions need not rely upon the human factor, and natural options should be considered first when addressing sea level rise. With some help, coral reefs and mangroves, where their growth is supported by the optimal environment, would be instrumental by being relatively simple to implement, at the same time as yielding positive long-term results through habitat restoration and carbon absorption. In more ways than one, on coastal fronts, these natural solutions can address the causes and impacts of sea level rise.