High Tides Hit Home
High Tides Hit Home
King Tides are a non-scientific term for the highest tides of the year, occurring when the gravitational pull from alignment of the Earth, moon, and sun align brings ocean water higher up our beaches and into low-lying neighborhoods. Here is a scene from Marina Beach, or Mother’s Beach, in Marina del Rey during a recent high-tide flooding event. Kick off 2026 by getting out and documenting high water during the next King Tide event, January 2 and 3.
Our “King Tides season” occurs during the winter — typically November through January — and serves as a preview of where baseline water heights will be with continuing sea-level rise. This regular and predictable occurrence offers a critical community science opportunity. Through photo-documentation, community and climate scientists can: document current flood risk and impacts in coastal areas; visualize the impacts of future sea-level rise in a community; ground-truth and validate climate change models by comparing predications with observations; and, serve as a living record of change for future generations. This is essential data for actions needed today and for planning for tomorrow. Here we take a deeper dive into local sea-level rise.
What is sea-level rise?
When water warms it expands and when more water is put into a vessel the level goes up. This is what’s happening due to human-driven global heating from the burning of fossil fuels. The oceans have absorbed much of this excess heat, and hotter air temperatures are melting land-based glaciers and ice sheets, which are draining into the oceans. Sea-level rise is one of the stresses of climate change that exacerbates other event-based hazards or shocks, in this case coastal hazards such as high waves and erosion. There has been gradual measured sea-level rise through the 1900s with an accelerated rate in recent decades.
How will it affect L.A. County shorelines -- in near future and in decades to come? And, what are the biggest threats facing residents and animal life?
The LA County Climate Vulnerability Assessment evaluated the social and physical risks of climate hazards. Sea-level rise impacts are both visible and not. Sea-level rise exacerbates our known coastal hazards, such as high tides, coastal storms, and erosion processes. Sea-level rise can also raise water tables near the coast, increasing severity of flooding and affecting below-ground infrastructure, and increasing the pressure of saltwater intrusion into coastal aquifers.
Absent proactive work this can mean nuisance or permanent flooding of streets and property, insurance impacts due to greater flood risks, damage to infrastructure, and other economic losses to businesses, tourism, etc. It can also result in ecosystem degradation from eroding beaches or drowned wetlands, impacting important wildlife habitat and those natural systems that also provide storm and flood protections for human communities.
Among the most alarming, predicted impacts:
- Southern California could lose up to two-thirds of its beaches by 2100 to sea-level rise and erosion if we fail to act.
- Disappearing or impaired beaches in Santa Monica Bay could lead up to $60M of losses in annual economic activity.
- Nearly one in six federally listed endangered species are at risk of extinction to sea-level rise due to loss of habitat.
How have our local shorelines evolved over time?
The coast is a dynamic setting, always undergoing natural and manmade changes. The L.A. County coast as we know it today is constructed: from the Ports of Long Beach and Los Angeles, to breakwaters and piers and marinas, and previously, oil wells that littered the coast. Historically the beaches were not as wide as they are today. Through the 1900s there were many large-scale sand placement and beach nourishment projects and other coastal developments on top of coastal dunes and on the ocean side of the Pacific Coast Highway, including sea walls.
What can we do now to best prepare against inevitable sea-level rise?
Ensuring access to and along the coast for recreational, subsistence, and economic benefits will require continued coastal management. Enhancing and protecting coastal habitats will require both hands-on and hands-off measures. This will all require community discussions and alignment on the objectives of coastal management and support for those actions. Fortunately, community planning and projects development are underway. Additionally, the 2025 OurCounty Sustainability Plan outlays several actions that ensure that land use, infrastructure, and coastal habitats and natural resources protections are future-forward and guided by sea-level rise projections. The good news is that studies have shown that every $1 invested now in shoreline resilience, such as building sand dunes and other natural buffers, will save taxpayers an estimated $10 in future damages.
What steps are County leaders taking to build in more resilience along the shorelines? What are some specific programs being put in place?
The County Department of Beaches & Harbors completed a Coastal Resilience Study and, in partnership with the coastal cities from Malibu to Torrance, is developing a Regional Coastal Strategic Adaptation Plan for the stretch of coastline from Leo Carrillo Beach to Torrance Beach. The plan aims to coordinate resilience efforts across multiple jurisdictions and will be informed by both scientific data and community input. As part of this effort, the County has launched a regional shoreline monitoring program to collect data that supports long-term planning and decision-making. The final plan will identify and prioritize resilience projects, recommend funding strategies, and outline coalition structures to support implementation.
The County is also developing and implementing demonstration living shoreline projects with input from coastal management partners, community-based organizations, academia, and the public. Additionally, to combat coastal erosion, the County is piloting the beneficial reuse of sediment from inland sources, such as flood control infrastructure. The Sand Compatibility & Opportunistic Use Program (SCOUP) aims to increase the resilience of coastal areas by streamlining environmental review and regulatory approval for beach nourishment with locally available sand sources. Lastly, in addition to recently securing several state grants, the County is developing a first-ever Climate Budget, to best-align our investments with our sustainability and resilience goals.
What role can federal and state agencies play in protecting against SLR?
There are multiple regulatory and resourcing roles that the federal and state governments serve for shared coastal management with local governments. The California Coastal Commission provides support and decision-making guidance for local coastal adaptation plans. The California Coastal Conservancy funds nature-based resilience projects along the coasts, to enhance climate resilience. Similarly, the U.S. Army Corps of Engineers is a permitting agency for certain coastal and marine efforts, as well as, a funding and/or project partner on other efforts such as harbor dredging and beach nourishment.
How can residents help?
There are many opportunities for residents to be directly hands-on and lend their voice to find the best paths forward. Residents can participate in the King Tide data collection process by documenting high-water level events. Residents can volunteer at events to support dune, wetland, and coastal habitat restorations and cleanups. Residents can research local resilience plans and attend public meetings to share their visions and support for community coastal resilience. Residents can participate in local elections and vote for policies and leaders that prioritize climate change resilience and adaptation work, and advocate for protection of communities most impacted by climate change.
How do we put sea-level rise in context with other environmental priorities? Aren’t there more immediate concerns to address?
Sea-level rise is one of many pressing community and climate concerns to address, along with, for example, wildfire threats, air quality concerns, drought, extreme heat, and housing affordability. Sea-level rise is a climate stress. It is a changing baseline, and its rate of increase is accelerating. It makes other coastal hazards more severe. Though it can seem an issue of limited scale and impacts may seem far-off, we also know it takes time to coordinate community visioning, and design, fund, and take actions. Sea-level rise affects multiple systems, and preparation increases resilience for coastal communities and habitats, and non-coastal residents and visitors, shaping the L.A. County coast for generations to come. With change coming to our shoreline the time for action is now.