Sea-level rise can be confusing. Here we answer basic questions.

The Basics

The planet is warming from heat-trapped gases. That’s causing ice sheets and glaciers to melt, and warming sea water to expand. Greenland and Antarctica are home to most of earth’s glacial ice and the only places with ice sheets or thick slabs on ice up to 15,000 feet thick.  This is where most of the freshwater is stored on Earth.  As heat is absorbed in the ocean, temperatures increase, causing expansion. To test this, place a flask of cold water and measure the level. Then heat the water up and measure the rise in the level.  Warmer water expands and takes up more volume.  This is happening at a global scale.

Unfortunately, no. Even if we ceased all greenhouse emission today, the seas would still rise because of all the damage we’ve done over the past 50 years. Sea level rise can’t be halted, but it can be managed. Most preparation will be conducted by local governments, which need to create formal adaptation plans. That means earmarking funds to conduct vulnerability studies and building resilience into all civic planning.

The state, coastal communities, and private property owners essentially have three categories of strategies for responding to the threat that sea level rise poses to assets such as buildings, other infrastructure, beaches, and wetlands. Specifically, they can (1) protect, by building hard or soft barriers to try to stop or buffer the encroaching water and keep the assets from flooding; (2) accommodate, by modifying the assets so that they can manage regular or periodic flooding; or (3) relocate, by moving assets from the potential flood zone to higher ground or further inland.

Predicting flood risk involves estimating future sea level rise compared to elevation, and our knowledge of both are limited The placement of defenses like levees, canals, and water diversion systems defy predictions.  Extreme high tides in winter (King Tides) and high rainfall during El Nino events pose extreme risk to low-lying coastal areas. Extreme winter storms are causing catastrophic flooding and erosion in places like San Francisco Bay, Pacific, and Imperial Beach.  Inland communities are also witnessing effects. Seawater is pushing farther inland through rivers and aquifers, threatening groundwater supplies.  Wells and groundwater in Salinas Valley, Los Angeles and Oxnard are becoming salty as the sea marches inland.

The Impacts

Nearly six out of 10 California beaches could disappear by century’s end.  If a beach is trapped between rising seas and coastal development, it cannot move inland.  Beaches will become squeezed, with the loss of beach space up and down our state.  This mean loss of recreational space for people, and less habitat. Rising seas will drown most wetlands on the U.S. West Coast within the century. Losing coastal marshes causes much harm, as they protect us from storm surge and store carbon that helps slow warming trends.

More frequent flooding and inundation threaten coastal communities and their public services.  Major roadways, hospitals, ports, marinas and utilities are in the cross-hairs. Our most critical transportation hubs are at risk, which could lead to billions of dollars in lost productivity and shutdowns. Places like SFO airport, the Port of Long Beach and San Diego harbor could need billions of dollars to upgrade, according to a report from the state's Legislative Analyst's Office. Erosion and flooding could cripple coastal connectors like Pacific Coast Highway and Amtrak rail lines. Power plants and sewage treatment plants could be forced to retrofit or relocate at great cost. Those expenses will ultimately be passed onto the public or communities.

Nearly $150 billion in property statewide is at risk of flooding by 2100. Salt-water intrusion will hurt California’s $50 billion agricultural industry. Increased salinity in farming areas decreases yields and revenue. Even worse, residents could be on the hook fo billions in repairs statewide.  If we fail to fund resilience planning now, the price is sure to rise exponentially in decades to come.

More than 1 million Californians are employed in ocean-related industries, which would suffer the brunt of impacts. The good news is that resilience planning could provide thousands of new jobs while protecting existing ones.

Yes, sea level rise impacts will be felt most immediately in coastal regions particularly in low-income neighborhoods. But the threats reach far beyond the shoreline. Whether you live in Malibu or Modesto, you will be harmed by rising oceans. The defining feature of our Golden State – its iconic coastline and beaches – are in danger of being washed away. And beaches belong to all Californians, not just homeowners along the coast. On the economic front, residents could on the hook for up to billions in infrastructure repairs if we fail to act.

While many coastal regions contain affluent neighborhoods, many communities include more vulnerable populations, such as Imperial Beach in San Diego County.  Low-income residents and communities of color have fewer resources to withstand impacts. Others at greater risk include the disabled, renters, the elderly and people who are linguistically isolated. In the event of a four-foot sea level rise, nearly 28,000 San Francisco residents classified as “socially vulnerable” would experience daily flooding, according to a recent study.

Flooding has the potential to inundate coastal beaches, dunes, and wetlands. This threatens to impair or eliminate important habitats for fish, plants, marine mammals, and migratory birds. Higher sea levels will also cause salt water to encroach into—thereby degrading—coastal estuaries where fish and wildlife currently depend upon freshwater conditions. A 2018 report by the State Coastal Conservancy and The Nature Conservancy found that 55% of California’s existing coastal habitats are highly vulnerable to five feet of sea level rise. The researchers estimated that five feet of sea level rise would also drown 41,000 acres of public conservation lands and add stress to 39 species whose populations have already been classified as rare, threatened, or endangered.

Stemming the Tide

Although much of the work to prepare needs to take place at the local level, the state can help. For example, the state can help (1) foster regional‑scale collaboration; (2) support local planning and adaptation projects; (3) provide information, assistance, and support; and (4) enhance public awareness of risks and impacts. Please see, Preparing for Rising Seas: How the State Can Help Support Local Coastal Adaptation Efforts for more discussion of how the Legislature can support local governments in their preparation efforts.

Predicting exactly how much seas will rise in California in the coming decades  -- and how individual communities will be impacted  -- is an inexact science. Thus, it’s impossible to put a definitive price tag on the multiple resilience projects that will need to be undertaken in the coming decades to protect homes, businesses, wetlands, beaches and key infrastructure.

Securing funds for necessary adaptation and resilience projects along the California coastline is a complex task, involving federal, state, regional and local agencies.  Potential federal funding sources include the Federal Emergency Management Agency, the Army Corps of Engineers, and community block grants from the Department of Housing and Urban Development. State legislators may look at creating bond measures to protect infrastructure and natural places, following funding mechanisms that allow us to manage water supply or prepare for earthquakes. At the local level, cities are issuing local resilience bonds, increasing stormwater fees or creating special service districts in which residents tax themselves to pay for resilience planning, wetlands/dune restorations and other adaptation projects.

In early 2020, the California Natural Resources Agency (CNRA) and the California Environmental Protection Agency (CalEPA) convened two high-level meetings of 17 state agencies to develop and approve overarching state Sea Level Rise Principles for use in planning, policy setting, project development, and decision making. The Principles have been endorsed by both CNRA and CalEPA secretaries and all departments within these agencies. The Principles are a living document, and formal endorsement of the Principles from other agencies will be added as received. The following State agencies are involved CNRA, CalEPA, SF Bay Conservation and Development Commission, California Coastal Commission, California Energy Commission, California Department of Fish and Wildlife, Caltrans, Delta Stewardship Council, Department of Water Resources, Ocean Protection Council, Governor’s Office of Planning and Research, Office of Emergency Services, State Coastal Conservancy, State Lands Commission, State Parks, State Water Resources Control Board and Strategic Growth Council.

The vision of the Leadership team is to reduce risks from sea level rise, storms, erosion and other coastal hazards, as individual agencies, collectively, and with the efforts of other partners. The Leadership Team works to increase its collective capacity to address sea level rise, implement the State’s Safeguarding Plan, coordinate on key actions and legislative briefings, and communicate how California state agencies are collectively addressing risk reduction for sea level rise.

Government entities can not hope to solve the battle single-handedly. Most resilience planning will be done at the local level. Community stakeholders — homeowners, business owners, environmental organizations and social service nonprofits — know local economic and geographic conditions best. They must work together — with state guidance — to arrive at common-sense solutions that provide long-term resilience at a reasonable cost.

Success is a California that is resilient to a 3.5 foot sea level rise by 2050.  In addition, California should have a flexible statewide adaptation plan in place, and every local county should have adaptation plans with tangible solutions included.  We will know we are making progress when California has scaled up resiliency efforts through aligned strategies that create efficient, consistent decision-making processes and actions through working collaboratively with state, local, tribal, regional and federal partners.

How You Can Help

Planning and adaptation is a multi-step, multi-decade initiative. The first step is increasing public awareness about rising seas in California and creating a greater sense of urgency about the need to actively plan and prepare at the local level. Simply put, the campaign aims to put sea level rise higher on the list of considerations for the average California resident. The campaign aims to educate Californians about the challenge and how to best meet it, while encouraging them to nudge local elected leaders to prioritize funding for local resilience planning. The campaign is funded by a state grant from the California Natural Resources Agency that is administered by nonprofit California Marine Sanctuary Foundation.

Beyond this website, residents can get regular updates about sea level rise by signing up for our newsletter, following our social media feeds and keeping any eye out for our digital promotions. We’ll keep you updated about the progress of resilience projects throughout the state and how you can get involved in local efforts to better prepare.

You can help educate California by sharing information on your networks. Sign up for our newsletter. Follow our feeds. Post a photo. Apply a filter to your IG stories. Talk to your family, friends and co-workers. Ask the hard questions of your city council or county board of supervisors: Does our community have a coastal resilience plan? If so, have we prioritized adaptation plans in the highest risk zones? If not, how do we secure funds to conduct vulnerability studies? 

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