2026-06-22 カリフォルニア大学サンタバーバラ校（UCSB）
Photo Credit:Courtesy Image
A side-by-side comparison of Humboldt Bay sand dunes with data taken in 1854 (left), 1948 (middle) and (2016) right
＜関連情報＞
- https://news.ucsb.edu/2026/022658/california-has-lost-more-half-its-coastal-sand-dunes-first-ever-comprehensive
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025EF007790
深刻な沿岸砂丘の消失が、カリフォルニア州の気候変動への耐性と生物多様性の目標に課題を突きつける Significant Coastal Dune Loss Challenges California’s Climate Resilience and Biodiversity Goals
T. I. Baxter, I. J. Walker, J. E. Dugan, D. M. Hubbard, L. Engeman, K. A. Emery, S. Vitousek, K. K. Johnston, A. J. Pickart, S. Smith, D. R. Fee, D. Willett, J. Wisniewski
Earth’s Future Published: 22 June 2026
DOI:https://doi.org/10.1029/2025EF007790
Abstract
Coastal sand dunes support unique biodiversity and buffer beaches and communities against storm impacts. However, these sensitive and dynamic ecosystems are increasingly threatened by erosion, sea-level rise (SLR), and encroaching coastal development. Restoration projects designed to re-establish the eco-geomorphic functions of degraded dunes and associated ecosystem services present a viable pathway to relieve these stressors. Yet, even for populated coasts like California, insufficient information on the location of dunes and patterns of change over time constrain regional efforts to identify suitable restoration/conservation sites, and forecast future impacts on vulnerable beach–dune systems. Here, we present a comprehensive assessment of coastal dune extent and loss, spanning 165 years and 9.5° of latitude across California. Areas and drivers of change were quantified by comparing historical and current dune extents generated using historical surveys, high-resolution aerial imagery, and LiDAR, combined with a machine-learning tool. Coastal dunes currently extend along 352 km (22%) of California’s 1,625 km coastline, covering almost 300 km2. This represents a 60% (442 km2) decrease in area since the mid-1800s with the loss, degradation, and fragmentation of many dune ecosystems attributed to urban development, altered land-uses, and erosion. Strong regional patterns of dune loss were evident, reflecting population demographics and land uses. Densely populated areas of southern California experienced the greatest dune losses (95%, 108 km2), although substantial reductions were also found in central California (60%, 331 km2). Our results highlight the magnitude of coastal change in California over time and can inform future conservation, restoration, and resilience-planning efforts and priorities.
Plain Language Summary
California has some of the largest and most ecologically diverse coastal sand dunes in North America. These dunes protect coastal communities from flooding and have important ecological, recreational, and cultural benefits, but are increasingly threatened by rising sea levels and coastal development. Efforts to restore these vulnerable ecosystems and forecast future climate change impacts are hindered by a lack of information regarding the location and spatial extent of coastal dunes, and reasons for their demise. Using historical maps and modern aerial photographs, we conducted a comprehensive, statewide assessment of coastal dune extent and loss. Since the mid-1800s, total dune area has decreased by 60% due to urban development, erosion, and land use changes. Dune ecosystems are significantly more isolated and fragmented than in the past, with losses concentrated in southern and central California. The magnitude of these losses over the last 165 years represents a significant challenge to California’s climate resilience, SLR adaptation, and biodiversity goals. Our methods provide a framework for assessing large-scale habitat change that could be extended to coasts around the world to aid the identification and prioritization of suitable restoration sites, helping to offset past dune losses and mitigate future climate change impacts.
