Coastal reclamation poses a significant threat to the ecological integrity and sustainability of China's coastal zone, prompting the implementation of stricter regulatory controls in recent years. However, a comprehensive understanding of long-term reclamation dynamics and the effectiveness of conservation initiatives over the past few decades remains limited. This study first quantified reclaimed areas and analyzed their spatial variability across multiple spatiotemporal scales using remote sensing-based land use and land cover change dataset (1990-2020). We then evaluated long-term trends in reclamation activities in relation to economic growth and policy interventions, which were hypothesized as primary drivers of reclamation dynamics. Our results indicate that land reclamation occurred extensively across all coastal regions, with the largest cumulative reclaimed areas concentrated in Shandong, Liaoning, and Jiangsu provinces. Each of these provinces exceeded 1,800 km2, collectively accounting for approximately 11,592.0 km2 of reclaimed land from 1990 to 2020. Reclamation expanded rapidly during 2000-2012 (40.9 km2 /yr), followed by a pronounced decline post-2012 (- 38.0 km2 /yr). This transition coincided with the implementation of policy-driven conservation measures, including the establishment of protected areas. Nevertheless, substantial spatial heterogeneity in reclamation patterns persisted, which reflected the influence of local development priorities and the variable effectiveness of regional conservation strategies. These findings suggest that China's coastal zone is undergoing a transformative shift from land-dependent development toward greener and more sustainable pathways. This study provides robust scientific evidence to support coastal management and offers critical insights for policymakers and stakeholders addressing coastal sustainability challenges at both regional and global scales.

Salt marsh soil organic carbon (SOC) is a key blue carbon pool affected by both disturbance and restoration; yet its long-term global dynamics remains poorly understood. Here we provide the global assessment of surface SOC changes in salt marshes from 2002 to 2019, combining multi-source remote sensing imagery with the machine learning calibrated by field observations. We find a net global SOC loss of 0.52 million tonnes, primarily driven by declines in North America and Oceania, which are only partially offset by gains in Asia and South America. The United States alone accounts for ~60% of the global loss, equivalent to 6.2 million tonnes of CO2 if fully released. Losses are concentrated in mature salt marshes with large SOC storage, while gains occur primarily in newly formed salt marshes with relatively low SOC density. These patterns suggest that global restoration efforts are failing to keep pace with degradation. To avert irreversible climate and ecological damage, the protection of mature, carbon-rich salt marshes must become a core component of global climate strategies.

Mangrove forests possess the capacity to respond to sea level rise, which can be decomposed into adaptability and resilience. Adaptability is primarily measured by the suitable habitat area of mangroves following landward migration, while resilience refers to the ability of mature mangrove forests to maintain their original distribution and functions under sea level rise. However, existing research rarely distinguishes between adaptability and resilience, nor explicitly differentiates the impacts of anthropogenic pressures on these two aspects. This study developed an integrated framework using Sea Level Affecting Marshes Model (SLAMM) to predict mangrove adaptability and resilience under sea level rise scenarios and Geographical Detectors for Assessing Spatial Factors (GeoDetector) to assess their exposure to anthropogenic disturbances. The research focused on Guangdong Province, the largest mangrove area in China, and provided projections for 2070 under the RCP4.5 and RCP8.5 scenarios. The results suggest that under the combined effects of sea level rise and coastal land use, mangrove resilience would decline more markedly than adaptability. By 2070, suitable mangrove habitat is projected to decline to 49.73 %-72.01 % of the current extent, with only 31.26 %-68.67 % of the present mangrove area persisting as resilient mangroves. A significant portion of the lost mangroves would consist of highly diverse, mature mangrove communities. Furthermore, the spatial distribution of terrestrial anthropogenic pressures, primarily from aquaculture ponds and industrial centers, would exert differential impacts on mangrove responses. Aquaculture would mainly affect mangrove adaptability, while industrial development would primarily influence mangrove resilience. By 2070, 28.89 %-40.23 % of the suitable mangrove habitats would be subjected to high levels of anthropogenic pressure, compared to only 0.92 %-2.08 % of the resilient mangroves. The study's findings suggest that enhancing mangrove adaptability and resilience in response to sea level rise will require differentiated approaches and measures. The proposed framework, which can be adapted to mangrove habitat studies in other regions with appropriate local datasets, provides practical tools for the adaptive management of mangrove ecosystems under global change.

Global environmental issues are becoming increasingly severe, with climate change imposing varying degrees of economic impact on different cities. It is crucial for cities to pursue efficient, low-carbon, and sustainable development pathways to cope with climate change. Carbon emission efficiency (CEE) is an essential indicator for assessing their performance and progress toward low-carbon growth. However, traditional CEE assessments have yet to integrate regional differences in the socioeconomic costs of climate change. To fill this gap, we have built a combined efficient frontier Data Envelopment Analysis (DEA) model based on the weighted carbon emissions of each city’s climate costs to evaluate the CEEs of 252 cities in China from 2006 to 2021. Meanwhile, city classification and spatial Markov chains are used for spatio-temporal heterogeneity analysis, and finally, the efficiency is decomposed to determine the impact of different factors on carbon efficiency. The results indicate that the average CEE of coastal cities (0.57) is lower than that of inland cities (0.63), mainly due to higher climate costs and unbalanced development. In contrast, megacities and super-large cities in coastal areas have the highest CEE levels because of economies of scale and technological advantages. Efficiency decomposition shows that pure technical efficiency (PTE) is the primary driver of CEE differences, contributing 33.37% to inefficiency differences. Our findings emphasize the need for targeted, differentiated policies to address unique urban challenges. Green technology investments should be prioritized in areas with high emission reduction potential, while cross-regional technology diffusion mechanisms should be established in areas with medium reduction potential to foster innovation. Overall, this study could offer valuable insights into the sustainable and low-carbon transition of urban development.

Marine trade, as a vital growth point for sustainable ocean-based economy, offers a critical pathway for achieving sustainable development goals (SDGs). Inclusive green growth (IGG) has become widely recognized as an important indicator to measure a country's progress toward SDGs. However, the mechanisms through which marine trade influences national IGG, as well as the varying degrees of its impact across countries, remain insufficiently understood. Anchored in the frameworks of blue growth and blue justice, this study constructs a theoretical model integrating factor integration, operational efficiency, and green low-carbon transition. Based on this framework, this study quantified marine trade in 62 representative countries and analyzed its impact on IGG through both theoretical and empirical according to the UNCTAD classification of sustainable ocean-based economy. The results revealed that the relationship between the scale of marine trade and national IGG follows a positive N-shaped curve. Furthermore, heterogeneity analysis indicated that marginal increases in marine trade have a more pronounced impact on IGG in African countries. These findings suggest that marine trade functions not only as an economic driver, but also as a governance mechanism that shapes ecological sustainability, institutional equity, and social inclusion. The study provides important insights for enhancing trade cooperation among leading maritime economies and informing policy design in developing countries with smaller markets and remote geographies. Ultimately, these findings advance global efforts toward achieving SDGs and fostering resilient ocean-based economies.

Maritime transport faces growing pressure to align with global net-zero targets, yet investment and operational decisions remain constrained by uncertainty surrounding alternative fuels and decarbonization technologies. Most existing assessments rely on static assumptions and do not capture how transition risks change in different scenarios or interact across political, economic, and technical dimensions. This study develops a multi-risk framework that evaluates six alternative fuels and a broad suite of energy-saving technologies by combining the Entropy Weight Method with Monte Carlo simulation. The framework not only generates risk indices and ranges but also projects the shifting profiles under multiple regulatory and market scenarios from 2025 to 2050. The results show that dominant risk drivers shift over time. Economic factors strongly influence near-term choices, while political and regulatory uncertainties become increasingly important as net-zero regulations tighten. The analysis also identifies a two-stage pattern in technology risks, where early risks are shaped by maturity constraints and later risks are shaped mainly by cost competitiveness. These varying risks create distinct trade-offs between affordability, risk exposure, and well-to-wake emission reduction. From the perspective of the individual performance of fuels and technologies, biofuels and operational measures support lower risk transitions in the short term, while green hydrogen and onboard carbon capture system may become attractive in stricter future policy environments because of their high emission-reduction potential. The study also develops a scenario-based combination evaluation framework to identify the optimal combined fuel-technology pathways under different decision supports for cost, risk, and emission reduction. The framework provides actionable evidence for shipowners, investors, and regulators seeking resilient pathways toward net-zero maritime transport.

Decarbonization is fundamentally reshaping maritime asset valuation, yet traditional models struggle to capture the complex, non-linear capitalization of environmental attributes. This study constructs an interpretable Stacking ensemble framework to decipher the value of green using the Fuel Efficiency Index (FEI), analyzing 5,645 second-hand bulk carrier transactions (2005-2023). The model achieves superior predictive precision (R2 = 0.9253, RMSE = 0,2043) compared to individual algorithms. Empirical evidence reveals that the capitalization of FEI is state-dependent and asymmetric, functioning primarily as a penalty for inefficiency rather than a uniform premium. Temporal interaction analysis identifies a structural intensification of this valuation effect following the 2018 IMO GHG strategy. Furthermore, SHAP analysis confirms that superior FEI effectively mitigates depreciation risks in older tonnage, identifying a mechanism for asset value recovery. Consequently, we propose a "Visibility-Valuation-Viability" policy framework to bridge information asymmetries and financing frictions, facilitating the decarbonization of the existing fleet.

Blue economy relies on a healthy ocean, where marine natural capital supports ocean industry activities and sustain the blue well-being that refers to a positive state for people which is determined by coastal and marine space. For coastal countries dominated by land-based economies, such as China, the development of the ocean industry is largely influenced by local land-based economies, which have significant impacts on the sustainable provision of blue well-being from marine natural capital. However, effects of land-ocean economic interaction on the exploitation of marine natural capital and blue well-being remain unclear. To fill these gaps, we quantified the marine natural capital of Chinese coastal waters at the county level, then explored the relationship between marine natural capital distribution and utilization, and land-ocean economic coordination level over a decade. We constructed an index of marine natural capital efficiency (MNCE) to reflect both the socioeconomic and natural wealth carried by per unit blue space and to determine which coastal regions’ marine natural capital were more effective in prompting objective blue well-being. The results indicate that the land-ocean economic coordination level has a significant positive association with MNCE. Marine natural capital in the coastal regions with low land-ocean economic coordination level are generally less efficient in objective promoting blue well-being. Based on an inter-regional coalition model, we offer recommendations for China’s coastal regions to select optimizing economic cooperation coalitions. Under the recommended coalition scenario, an improved land-ocean economic coordination level could increase the overall MNCE in China by 60.19%. This could either enhance the available marine natural capital flow by 69.89% or increase the ocean industry production by 69.68%, which could boost objective blue well-being through the efficient use of natural capital to promote broader ocean economy growth. We suggest strengthening regional cooperation and coordinating land-ocean economic interactions to boost objective blue well-being for coastal communities by using marine resources efficiently and equitably.

Promoting sustainable development worldwide requires collaborative efforts across interconnected systems under integrated frameworks. Here, we illustrate the integrated metacoupling framework as a holistic lens for analyzing human-nature interactions within and between systems to advance integrated sustainability analysis. We propose six interrelated steps to operationalize the framework for Sustainable Development Goals’ interaction analysis, progress assessment, and pathway modeling, contributing to the integration of knowledge for the 2030 Agenda and emphasizing “Leave No One Behind”. We demonstrate that the framework offers interdisciplinary researchers a practical toolkit and supports policymakers in developing synergistic cross-system strategies for sustainable development across local to global scales.

Climate change is reshaping marine fish habitats. Yet the future habitats' redistribution of fishes that are both critically endangered (CR) and globally commercially exploited remains poorly understood. Here, we assessed current and future suitable habitats for 24 CR commercial coastal demersal fishes selected on the IUCN Red List. Using ensemble species distribution models (SDMs), we projected habitat suitability under SSP1-2.6 and SSP5-8.5 by the 2100 s, and combined the projections with exclusive economic zones (EEZs), marine protected areas (MPAs), and fishing pressure. Most species were projected to experience net habitat contraction by the 2100 s, with stronger losses under SSP5-8.5 and pronounced declines in tropical and subtropical coastal waters. Across 145 coastal EEZs, projected species richness showed marked spatial heterogeneity, with Asia retaining the highest mean richness and Europe showing a net increase. Low-income and lower-middle-income countries supported substantial current species richness but faced stronger relative declines under SSP5-8.5. Projected habitats of CR commercial fishes intersected MPAs in only 49% of coastal countries, indicating substantial protection gaps. Overall, this study quantitatively delineates climate-driven habitat redistribution patterns of CR commercial fishes, suggesting potential implications for optimizing MPAs networks and advancing transboundary conservation strategies to promote marine biodiversity and sustainable fisheries development.

Long-term planning of offshore wind farms is essential for sustainable wind energy utilization. Currently, offshore wind farm siting in China is largely guided by policy priorities, often with insufficient integration of wind energy resource assessments and socio-ecological considerations. This may result in diminished project efficiency and elevated ecological and environmental costs. This study proposed a methodology that combined multisource heterogeneous data, enabling coupling of wind, ecological, and economic datasets. Using the Delphi method (Delphi) and Geographic Information System (GIS), scenarios were developed based on wind energy effects, ecological impacts, and economic costs. The results showed that ERA5 data was highly consistent with the regional wind energy performance. In the wind energy scenario, the high suitability sites were mainly located 50-75 km offshore in northern Fujian and southern Zhejiang, with an area of 142,114 km2. In the ecological scenario, the medium suitability sites were located at least 110 km offshore, and the high suitability sites were at least 260 km offshore. Although the ecological disturbance decreases with increasing offshore distance, the economic cost increases. In the economic scenario, the high suitability sites were located within 90-150 km offshore and covered an area of 150,769 km2. The total area of optimized high suitability sea area for wind farms was finally identified as 179,904 km2 through the weighting of the scenario indicators, of which 6106.83 km2 was located in the northern part of Fujian, 95 km offshore, and the rest of it was distributed in the sea area beyond 250 km offshore. In addition, current wind farms were mainly located in areas of low and medium suitability, emphasizing the potential for future wind power development in areas of high suitability. This novel approach provides a practical tool for optimizing offshore wind farm siting in China and offers a transferable framework applicable to other countries and regions with available multisource data, supporting more balanced and sustainable offshore wind development.

The port sector faces both challenges and opportunities in digital transformation and decarbonisation in the post-pandemic era. To address these issues, the Sixth Generation Port (6GP) model with smart ports comprising six aspects and 14 criteria was proposed, iteratively refined, and validated. In order to extend the test scope and assess the applicability of the 6GP model, this study aims to evaluate the performance of major world container ports, namely the Port of Singapore, Shanghai, Busan, Hong Kong, and Rotterdam, by applying the 6GP model with smart ports. An innovative hybrid methodology integrating CFPR, MOORA, and VIKOR was employed to explore the business needs and development priorities of port stakeholders and to assess each port’s performance with reference to the 6GP model. The test results indicate that the Port of Singapore, Rotterdam, and Shanghai performanc, with Asian container ports achieved better performance in "service" and "smart port governance system and policy". Specifically, Shanghai has emphasized automation optimisation to facilitate the seamless cargo and vessel flows, while Rotterdam achieved significant performance in digitalisation and decarbonisation by fostering a smart port–city symbiosis. The contribution of this study lies in theoretical, methodological, and empirical aspects. i) Theoretically, it validates the applicability of the 6GP model, enriching the existing literature on Port Devolution Theory by integrating digitalisation and decarbonisation into the 6GP model; ii) Methodologically, it applies a novel hybrid CFPR–MOORA–VIKOR framework to enhance multi-criteria decision-making in port studies; iii) Empirically, it offers a comparative evaluation of container ports in both Asia and Europe, providing actionable insights for policymakers and port managers, and advocates collaborative action among different stakeholders.

Amid intensifying climate urgency, decarbonizing marine economic sectors presents both a critical challenge and a pivotal opportunity in global mitigation strategies. However, systematic approaches to assessing reduction potential remain limited. Here, we developed an integrated analytical framework with statistical data and found a 28.35

Due to varying degrees of human disturbance, many estuaries face degradation and habitat collapse. It's urgent for us to acknowledge the estuaries' health status. Environmental carrying capacity (ECC) is a widely-used tool assess environments' sustainable condition, but effective evaluation methods especially for estuaries remain scarce. This study established a comprehensive estuary ECC assessment system based on pressure and support capacities and applied it to quantitatively evaluate the Aojiang estuary's ECC from 2005 to 2015. We also innovatively incorporated cumulative human pressures into the spatial quantification of ECC. Results show that Aojiang Estuary's ECC declined slightly from 1.01 (2005) to 0.94 (2010) and then to 0.97 (2015) while offshore places further away had higher human exposures and resultant lower ECC from the spatial view. We found the key drivers for ECC declining were rapid coastal reclamation, overfishing, industries activities, port development and tourism. Actionable policy suggestions are provided based the drivers analysis. The results enhance our understanding of spatiotemporal ECC patterns in Aojiang Estuary and other similar areas, helping policymakers to implement more targeted conservation policies to ensure a sustainable estuarine environment.

As maritime carbon emissions continue to rise, the need to improve the effectiveness and adaptability of global decarbonization policies has become increasingly urgent. However, fragmented governance structures and limited coordination among major actors have hindered progress toward a unified international transition. This study applies the Policy Modeling Consistency (PMC) index model to quantitatively assess the maritime decarbonization frameworks of the International Maritime Organization (IMO), the European Union (EU), and China across nine structural dimensions. The findings indicate that the IMO framework achieves the highest structural consistency with a PMC score of 8.017, followed by the EU Emissions Trading System (ETS) with 7.925, while China's national policies score 7.325. IMO policies emphasize global consensus and technical standard-setting but lack binding incentives, EU policies integrate legal mandates and market-based mechanisms with high coherence but heavy compliance costs, and China's framework demonstrates flexibility and fiscal support but weaker enforceability and limited engagement. These results highlight the methodological value of the PMC model in diagnosing policy strengths and deficiencies and provide evidence-based recommendations for enhancing international policy harmonization, adaptive carbon pricing, and balanced regulatory-incentive design to advance a coherent and resilient global maritime decarbonization regime.

Marine ecosystems provide material resources and development space for human production and life, which is crucial to economic development and human well-being. Coastal blue well-being refers to the positive states of human life in coastal areas supported by ecosystem services, including subjective emotional and cognitive dimensions as well as the objective natural, economic, and social dimensions. How to achieve the dual goals of protecting the ocean and improving human well-being is a core issue in ensuring marine sustainable development. When considering the connotation of coastal blue well-being, it is necessary to analyze the relationship between marine ecosystems and human well-being, and identify the coastal blue well-being components related to ecosystem services. Here, we sorted out the linkage framework and trade-off relationship between marine ecosystem services and coastal blue well-being based on the theory of well-being, and clarified the evaluation dimension of coastal blue well-being. This study would provide theoretical supports for dynamic monitoring of coastal blue well-being and the trade-off of related interests, as well as a theoretical basis for the program of improving coastal blue well-being.

Tidal variability and coastal upwelling are some of the most important processes in global shelf seas. With observations and high-resolution numerical simulation, we investigate the synoptic-to-intraseasonal variations in tidal temperature variability to the east of the Leizhou Peninsula and Qiongzhou Strait in the northern South China Sea and clarify the underlying dynamics. The results indicate that tidal temperature variability is most significant in a narrow meridional band in shallow waters (< 40 m) to the east of the Leizhou Peninsula and Qiongzhou Strait in the summer when there are strong thermal fronts located on the sea floor slope. The summer mean diurnal standard deviation of hourly temperature can reach up to 0.93°C. Tidal temperature variability in summer exhibits no spring-neap cycles but strong synoptic-to-intraseasonal variations, with the diurnal standard deviation of hourly temperature varying significantly from 0°C to 2.36°C. Further analyses indicate that synoptic-to-intraseasonal variations in tidal temperature variability in the summer are predominantly caused by wind-driven coastal upwelling. When southerly winds are weak, coastal upwelling is weak and leads to the offshore thermal front being located far away from the Leizhou Peninsula. Waters between the offshore thermal front and the Leizhou Peninsula/Qiongzhou Strait are mixed well and experience insignificant tidal temperature variability. When southerly winds are strong, coastal upwelling is strong and results in the offshore thermal front moving westward close to the Leizhou Peninsula. This facilitates the formation of the nearshore thermal front in combination with the complex topography and tidal currents. Tidal current-induced swinging of the nearshore thermal front then generates significant tidal temperature variability. The above results highlight the importance of coastal upwelling/downwelling in modulating tidal temperature variability near ocean thermal fronts in the shelf seas.

Commodities are usually transported in bulk and are associated with the risk of environmental pollution and cargo loss during intermodal transportation. This study discusses the containerization of bulk cargo with the coordination of bulk cargo transport and empty container repositioning. In such a transport network, a bulk cargo transportation company can use empty containers to load and deliver bulk cargo. We proposed models to analyze the optimal decisions regarding the number of leased empty containers under uncertain demand. We discussed three business modes to demonstrate the financial and resilience performance of bulk cargo containerization and supply chain coordination. Our results show that the trip-sharing mode can significantly increase the amount of bulk cargo containerization by reducing the transportation cost of empty containers that need to be repositioned. This model can help bulk cargo logistics companies determine the optimal number of released containers by considering profits and risk control. This study also sheds light on ways to promote supply chain resilience by incentivizing containerization and trip sharing.

To prevent excessive exploitation of sea resources by developers, countries around the world have established systems for managing sea use. The system of sea use fees in China is continually improving, but it cannot reflect the full value of marine natural resources. Therefore, an optimization mechanism for dynamic adjustment which considered the value of marine natural resources and the adjustment coefficient of sea area fees was constructed in the study. This study explored the difference between marine resources zoning and the dynamic adjustment standard of sea use fees collection and took Zhejiang province as an example. The results showed that the comprehensive scores of coastal marine resources were generally higher than those of the open sea in Zhejiang province. Furthermore, the comprehensive scores of important ecological areas such as bays and islands were higher than those of other marine areas, and the comprehensive score of Ningbo sea area was significantly higher than those of other sea areas. On the basis, there are six classes of the adjustment range of the sea use fees standard were divided in Zhejiang province in the study. The overall increase of fee was 3.9-8.0 %. The results of study can assist decision-making by evaluating the value of marine resources and the adjustment of sea area usage royalties, which will help to improve the efficiency of sea area management.