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The climate over the North Pacific and the related weather along the California coast have been related directly to Pacific Decadal Oscillation (PDO) cycles that oscillate between warmer, stormier, El Niñ o-dominated periods (in light gray) and generally cooler, calmer, La Niñ a-dominated periods (in dark gray). (Graphic courtesy JISAO University of Washington.)
Source publication
Coastal hazards involve the interaction or effects of natural coastal processes on shoreline development, infrastructure, and human activities. Future sea-level rise will affect California’s coastal development and infrastructure through both
flooding of low-lying areas and erosion of cliffs, bluffs, and dunes. The global rate of sea-level rise is...
Contexts in source publication
Context 1
... state's population grew from 9.3 million in 1945 to 22.8 million in 1978, or a 2.4-fold increase. In 1978, however, the climate over the North Pacific and along California's coast transitioned abruptly to a warm or positive PDO period characterized by larger, more frequent, and damaging El Niñ o events (Figure 8), which took their toll on coastal development and infrastructure (Griggs, Patsch, and Savoy, 2005). ...
Context 2
... large part of the motivation for the Coastal Act of 1976 was the need to provide protection for marine life and coastal habitats and to preserve public access to the shoreline, which was often under threat. It was written during the end of an approximately 30-year-long, relatively calm period in California's coastal climate (a cool or negative PDO cycle; Figure 8). Issues of coastal erosion and protection were less apparent than they would become in the subsequent warm or positive PDO period that began around 1978 and continued for the next 20 years. ...
Context 3
... state's population grew from 9.3 million in 1945 to 22.8 million in 1978, or a 2.4-fold increase. In 1978, however, the climate over the North Pacific and along California's coast transitioned abruptly to a warm or positive PDO period characterized by larger, more frequent, and damaging El Niñ o events (Figure 8), which took their toll on coastal development and infrastructure (Griggs, Patsch, and Savoy, 2005). ...
Context 4
... large part of the motivation for the Coastal Act of 1976 was the need to provide protection for marine life and coastal habitats and to preserve public access to the shoreline, which was often under threat. It was written during the end of an approximately 30-year-long, relatively calm period in California's coastal climate (a cool or negative PDO cycle; Figure 8). Issues of coastal erosion and protection were less apparent than they would become in the subsequent warm or positive PDO period that began around 1978 and continued for the next 20 years. ...
Citations
... Soft solutions are less effective in combating sea level rise and erosion to the coastal bluffs in California. Research has shown that beach nourishment, a soft solution, is not a sustainable strategy to mitigate sea level rise and erosion in California, as there are significant negative ecological consequences of beach nourishment (Griggs & Patsch, 2019). There have been several instances where beach nourishment has been attempted to reduce erosion and wave energy, but these have proven to be unsuccessful for coastal bluffs in California. ...
... There have been several instances where beach nourishment has been attempted to reduce erosion and wave energy, but these have proven to be unsuccessful for coastal bluffs in California. One example is the San Diego County Projects 1 and 2, also known as the Regional Beach Sand Projects (RBSP) I and II, which were implemented in various San Diego beaches (Griggs & Patsch, 2019). During the RBSP I and II, sand was placed in front of bluffs in an attempt to reduce wave energy and erosion (Griggs & Patsch, 2019). ...
... One example is the San Diego County Projects 1 and 2, also known as the Regional Beach Sand Projects (RBSP) I and II, which were implemented in various San Diego beaches (Griggs & Patsch, 2019). During the RBSP I and II, sand was placed in front of bluffs in an attempt to reduce wave energy and erosion (Griggs & Patsch, 2019). In these instances, 2.6 million cubic meters of sand was added to the county's beaches, most of which was eroded during the first year after nourishment (Griggs & Patsch, 2019). ...
... These structures can yield numerous positive outcomes when are properly designed and implemented [25,26]. Successful implementations can be found in the United States, Thailand, and Italy [22,27,28]. However, concerns remain about the environmental impact of these defense structures [26,29]. ...
Human activities like dam construction in rivers and urban development in coastal areas, combined with climate change, are degrading coastal systems. As a result, many European countries have implemented laws and strategies to protect their shorelines. This research focuses on Guardamar del Segura in Spain, where human actions in the Segura River basin and changes in wave patterns have significantly damaged the beach-dune system, with erosion rates reaching − 0.71 m/year. If these rates and extreme climate events continue to rise, the shoreline will keep retreating, leading to the destruction of beachfront houses and parts of the dune surface by 2050. This will cause changes in land ownership and irreversible ecological damage to the natural ecosystem. The Spanish Public Administration’s inaction on coastal protection is due to a lack of coordination between government levels, insufficient technical tools to combat erosion, and inadequate legal mechanisms to fund protective measures. In contrast, countries like Germany, the Netherlands, and the United Kingdom have effective models in place. Potential solutions for Guardamar del Segura include beach and dune restoration or adding sand through revetments. Another option is a managed retreat of the most vulnerable buildings to avoid continuous repair and maintenance costs. Coastal erosion is a growing issue, and preserving our coastal ecosystems requires proactive measures, so doing nothing is no solution.
... With options limited to unmanaged/unplanned retreat (i.e., do nothing), beach nourishment, hard armoring structures, living or green shorelines, and managed retreat or relocation, decisions will have a drastic effect on the future usability and accessibility of California's beaches (Caldwell and Segall 2007, Lester et al. 2022. Hard, shoreparallel armoring structures have been the typical historic response to coastal erosion in California, with 13.9% of the state's and 38% percent of southern California's coastline hardened with structures as of 2018 (Griggs and Patsch 2019b). California beaches -and their associated opportunities, features, facilities, and amenities 3 -are, therefore, caught in the so-called "coastal squeeze" (Lester and Matella 2016) between rising sea level and hardened shoreline development. ...
Climate change and associated sea level rise (SLR) will have substantial impacts on coastlines worldwide, threatening beaches, infrastructure, economies, and communities. In California, communities and individuals rely on the state’s public coastal access to physically reach and use the beaches and nearshore waters. Such use constitutes a key component of the state’s ocean-dependent coastal tourism and recreation sector,
and contributes significantly to state and local economies, coastal culture, and individual’s coastal attachment. This study
investigates the impacts of SLR on coastal access, first by using geospatial tools to develop a higher resolution database of the location and elevation of coastal access sites (opportunities,
amenities, and facilities, including parking) at various coastal access sites statewide. Then, using the Coastal Storm Modeling System (CoSMoS) SLR run-up model, we project the loss of coastal access opportunities due to SLR. We find that impacts to coastal access increase incrementally with SLR and vary widely by access feature type and location, with larger impacts accruing more rapidly in the southern half of the state. We project that access to California’s shoreline will drown at the rate of approximately 100 access opportunities per 1 foot of SLR. Losses of coastal access will impact individual communities and groups differently and are sensitive to the effects of different strategies designed to manage coastlines in the face of rising sea levels.
... Coastal defense strategies to mitigate flooding and erosion have historically relied upon the implementation of hard engineering structures such as bulkheads, seawalls, breakwaters, tetrapods, gabions, and groins (9,10). While these interventions can effectively reduce the impact of wave forces, they often come at a significant cost and can result in adverse wave reflection. ...
Increasing extreme weather events require a corresponding increase in coastal protection. We show that architected materials, which have macroscopic properties that differ from those of their constituent components, can increase wave energy dissipation by more than an order of magnitude over both natural and existing artificial reefs, while providing a biocompatible environment. We present a search that optimized their design through proper hydrodynamic modeling and experimental testing, validated their performance, and characterized sustainable materials for their construction.
... Wetlands remaining today are relatively small or discrete remnants comprising just 25% of areas that existed ca. 1850 due to land use conversion (Grossinger et al., 2011;Stein et al., 2014Stein et al., , 2020 and shoreline hardening (Griggs & Patsch, 2019). Wetlands here experience a semiarid, Mediterranean climate marked by dry, hot summers and cool, wet winters, making them sensitive to changes in hydrology. ...
The future of coastal wetlands will depend on the combined effects of climate change and human impacts from urbanization and coastal management. Disentangling the effects of these factors is difficult, but satellite imagery archives provide a way to track biological and physical changes in wetlands over recent decades to reveal how coastal wetlands have been changing in response to climate and human drivers. In this study, we used Landsat to monitor the conditions of 32 coastal wetlands in southern California from 1984 to 2019 and identify environmental and human drivers of these trends. Wetland conditions were characterized by vegetation greenness, using the normalized difference vegetation index (NDVI), and by habitat composition, derived from areal estimates of wetland and subtidal habitats. Overall, wetlands displayed three types of long-term response: greening and gaining wetland (10), greening and losing wetland (16), and browning and losing wetland (6). Regional environmental drivers with overall positive effects on wetland NDVI were sea level, wave height, and precipitation, whereas stream discharge, vapor pressure deficit, and air temperature had negative or nonlinear effects. Wetland area change was primarily correlated with sea level, but response was highly contextual among sites. Negative trends in wetland NDVI and area were more common in larger sites with low elevations and in sites with open inlets. Restoration had mixed effects, with only half of the restored sites showing positive changes in NDVI and wetland area post-restoration. The important work of managing and restoring urban coastal wetlands is complicated by variability and context and requires us to account for the influence of humans and climate as we build a regional understanding of historic, present, and future wetland health.
... This includes uncertainty in the trajectory of future changes related to climate forcing (e.g., sea-level rise, storminess), land use change and urbanization. It is also important to note that changes in political priorities may lead to certain management approaches being adopted (such as building a sea wall), whether or not it is appropriate [60,86,87]. This is because, from the viewpoint of politicians and local communities, NBS and enhancing the natural resilience of pre-existing coastal properties may be considered as a 'do nothing' approach rather than something that yields an immediate and decisive response to an issue of coastal erosion [87]. ...
... It is also important to note that changes in political priorities may lead to certain management approaches being adopted (such as building a sea wall), whether or not it is appropriate [60,86,87]. This is because, from the viewpoint of politicians and local communities, NBS and enhancing the natural resilience of pre-existing coastal properties may be considered as a 'do nothing' approach rather than something that yields an immediate and decisive response to an issue of coastal erosion [87]. Communication and education is, therefore, needed, which is why engaging with communities and stakeholders is important [69] (Table 1). ...
Natural coastal landforms such as sand dunes and sandy beaches have been proposed as green infrastructure that can reduce climate change risks along coastlines. As such, they can offer a nature-based solution to rising sea levels, increased storminess and wave erosion associated with climate change. However, these proposed advantages are not always based on a sound understanding of coastal sediment system dynamics or tested against field evidence of coastal morphodynamic behavior. This study critically examines the basis of the claim for coastal landforms as green infrastructure, by considering how and in what ways these landforms provide resilience against ongoing climate change along sandy coasts, and proposes a theoretical framework for understanding this relationship. The analysis highlights that natural coastal landforms do not always have properties that provide resilience against future climate change. They can only be considered as offering nature-based solutions against climate change when their pre-existing morphodynamic behavior is fully understood. Thus, not all coastal landforms can be considered as ‘green infrastructure’ and the resilience offered by them against climate change forcing may vary from one place or context to another. This should be considered when using landforms such as sandy beaches and sand dunes as nature-based solutions for coastal management purposes. A 10-step framework is proposed, guiding coastal managers on how such green infrastructure can be used to mitigate climate change risks along coasts.
... Adaptation options for responding to elevated sea levels and shoreline recession, whether short or long-term, are limited, and many coastal cities around the world are now struggling with future scenarios and risks to oceanfront development, whether public infrastructure or private development. While armor of one type or another (primarily seawalls and rock revetments) or beach nourishment have been the dominant historical approaches for dealing with shoreline recession or coastal erosion, the costs and impacts of these approaches have been questioned in recent years [6,7] with increasing proposals or recommendations for the use of living shorelines. This paper offers a critical assessment of the feasibility of using living shorelines along the high-energy California coast. ...
... In 1971, only 27.1 miles of the entire state's coast had been armored (2.5%), with 17 miles of that being in the four most densely developed southern California counties (Ventura, Los Angeles, Orange, and San Diego; [7]). By 1998, after two major El Niño winters, this had increased by 400%; 110.3 miles of the state's shoreline, or 10.3%, had been armored. ...
... A decade later, as more homes were threatened, armor coverage continued to expand so that by 2018, 148.7 miles had been protected, or 13.8% of the entire 1100 miles of state coastline. For the four most populated and developed southern California counties, these numbers reached 88.1 miles or 37.8%-over a third of the entire 233 miles of shoreline had been protected with some type of structure by 2018 (Table 1; Figure 3) [7]. The California Coastal Act of 1976 established a Coastal Commission of twelve politically appointed individuals to make decisions on coastal land use and permit issues and their consistency with the Coastal Act. ...
California and most other coastlines around the world are being impacted by both long-term sea-level rise and short-term extreme events. Due to California’s long and intensively developed coastline, it is an important area for evaluating responses to these challenges. The predominant historic approach to coastal erosion in California and globally has been the construction of hard coastal armoring such as seawalls and rock revetments. The concept of living shorelines—defined as using natural elements like plants, sand, or rocks to stabilize the coastline—has been widely proposed as a soft or green response to coastal erosion and flooding. However, these approaches have very limited application in high-energy environments such as California’s 1100-mile-long outer coast and are not realistic solutions for protection from wave attack at high tides or long-term sea-level rise. Each of the state’s coastal communities need to identify their most vulnerable areas, develop adaptation plans, and plan eventual relocation strategies in response to an accelerating sea-level rise.
... Assigned by the cabinet, the DPT has to ensure the well-being of coastal communities. It realized that the revetments can induce many environmental impacts (such as downdrift erosion, beach inaccessibility, and shortened front beach berm (Griggs and Patsch 2019). The DPT has carefully designed its revetment to minimize such negative shortcomings (Saengsupavanich 2022; Sanitwong-Na-Ayutthya et al. 2022). ...
Different countries practice various approaches to coastal erosion management, which have characteristics strengths and weaknesses. Protection of the land from coastal erosion is a complex task, and it depends on many socioeconomic and environmental factors. Asian countries have unique cultural, social, environmental, and political behaviors. Therefore, the objectives of this study are to analyze the current status of coastal management in Thailand, Malaysia, and Sri Lanka, and to synthesize a common coastal management framework for those countries. In this study, we analyzed the situation of coastal erosion, and the existing responsible government department and their legal authorities in Thailand, Malaysia, and Sri Lanka. After that, we evaluated specific challenges and common issues in the management of coastal erosion. The main challenges can be summarized as rapid urbanization and the construction of infrastructure along the coasts, rising sea levels as a consequence of climate change, inadequate coastal zone planning and management framework, a deficit of sediment supply compared to erosion rates, and face constraints in terms of financial and technical resources for coastal erosion management. A multi-faceted approach is required to address these challenges, and it combines both structural and non-structural measures. For example, this approach involves (i) sustainable coastal zone planning, (ii) the implementation of nature-based solutions, (iii) restoration of natural coastal features, (iv) regulation of coastal development activities, and (v) the integration of climate change considerations into coastal management practices. Finally, collaborative efforts among government agencies, researchers, local communities, and international organizations are crucial for successful coastal erosion management in Thailand, Malaysia, Sri Lanka, and potentially other Asian regions.
... In Italy, front beaches gradually became narrower after the implementation of revetments, and eventually disappeared altogether because they were experiencing a deficit in sediment supplies from rivers [46]. This conclusion was also supported by the findings of [18,45,47]; who mentioned that the fronting beach would be lost because of wave interactions with the revetments. The revetments can interrupt local sediment balance, whiles waves hitting the revetment are reflected downwards, scouring the toe of the revetment [48]. ...
... Beach beauty is a personal preference. Some coastal practitioners agree that the revetments enhance beach aesthetics [16,67], while some consider them an eye sore [18]. Reference [66] stated that repairing an aged revetment and topping it with a new pedestrian walkway was a preferred alternative to promote recreational activity and enhance an aesthetic view. ...
... They claimed that the recreational beaches in Puerto Rico were seriously degraded and even destroyed because the revetments were built on a crisis basis without considering other approaches. References [18,34] supported that the revetments would cause a loss in beach width, accessibility, and landscape quality, leading to a reduction in tourism attraction and a long-term negative impact on the tourism industry. However, removing the revetments for aesthetic reasons is not a wise choice because it can allow coastal erosion to re-happen and threaten nearby buildings' safety [41]. ...
Coastal structures, especially revetments, have been widely implemented to protect properties and infrastructures from erosive waves during storms. While being incompatible with nature-based solutions, revetments have still been constructed due to their effectiveness in solving coastal erosion. One of the most crucial concerns that should be considered as part of a revetment implementation is how to diminish and manage its possible impacts on the environment. Thus, a thorough understanding of how the revetments affect the surrounding environment must be achieved. This article critically reviews and summarizes their economic considerations, and environmental impacts on beach morphology, hydrodynamics, ecology, aesthetics, beach accessibility, beach recreation, and other notable aspects. Coastal practitioners and researchers, who are involved with the revetments, may increase their environmental awareness before implementing them. The revetments can be an excellent option to protect the eroding shoreline, if their possible environmental consequences are well-understood and properly managed.
... Humans are one of the world's great geomorphic agents and can both directly and indirectly influence the rate and nature of transgression (Lazarus et al. 2016); even modest amounts of development can override natural processes, altering coastal-system behavior across distances of hundreds of kilometers and for time periods lasting many decades (Armstrong & Lazarus 2019, Hapke et al. 2013). Along open-ocean coasts, direct human interference can accelerate transgression by reducing the resilience afforded by dunes (e.g., Nordstrom 2000) or slowing beach recovery following storms (e.g., Wernette et al. 2020) or can slow transgression through hardening of eroding cliffs or permafrost (e.g., Griggs & Patsch 2019, Liew et al. 2020, beach nourishment (e.g., Lazarus et al. 2016), and emplacement of hard or soft engineering structures and/or living shorelines (e.g., Alves et al. 2020, Cooper & McKenna 2008b. ...
Marine transgression associated with rising sea levels causes coastal erosion, landscape transitions, and displacement of human populations globally. This process takes two general forms. Along open-ocean coasts, active transgression occurs when sediment-delivery rates are unable to keep pace with accommodation creation, leading to wave-driven erosion and/or landward translation of coastal landforms. It is highly visible, rapid, and limited to narrow portions of the coast. In contrast, passive transgression is subtler and slower, and impacts broader areas. It occurs along low-energy, inland marine margins; follows existing upland contours; and is characterized predominantly by the landward translation of coastal ecosystems. The nature and relative rates of transgression along these competing margins lead to expansion and/or contraction of the coastal zone and—particularly under the influence of anthropogenic interventions—will dictate future coastal-ecosystem response to sea-level rise, as well as attendant, often inequitable, impacts on human populations.
Expected final online publication date for the Annual Review of Marine Science, Volume 16 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
