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.

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.

Migratory marine species are vital to ecosystem health and fisheries stability, yet their effective conservation is hindered by a mismatch between static protected areas and their dynamic migrations, as well as by anthropogenic pressure. Even advanced systematic conservation planning often relies on averaged data, overlooking spatiotemporal variations in habitat connectivity and risk. Here, we develop a generalizable framework integrating dynamic habitat connectivity with the spatiotemporal heterogeneity of fishing pressure, shifting focus from static locations to ecological processes. The framework combines machine-learning biomass predictions, circuit-theory connectivity modeling, and Bayesian spatiotemporal analysis of human pressure. Applied to the small yellow croaker (Larimichthys polyactis) in the Southern Yellow Sea and East China Sea, the framework captured seasonal migrations, revealing critical connectivity areas that shift from the nearshore waters of the Yangtze River Estuary in spring to offshore feeding and overwintering grounds. Fishing pressure was consistently elevated nearshore and increased over the study period in the Southern Yellow Sea. There was a pronounced spatiotemporal mismatch between the coverage of existing protected areas and areas at high risk of connectivity loss. In spring and winter, coverage of high-risk areas by existing protected areas was only 52.0

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

The ocean serves as a vital ecosystem for sustaining life on earth and ensuring human well-being. Presently, there is a significant surge in global demand for various ocean-based economic activities, including fishing, shipping, offshore wind energy production, maritime tourism, and so on. However, this growth has also resulted in an increase in emissions from marine sectors, which have not been thoroughly evaluated or analyzed. It is therefore necessary to conduct comprehensive evaluations of the current emissions, covering marine sectors. To address this need, through this Perspective, we have globally analyzed and discussed carbon emissions linked to maritime transportation, marine capture fisheries, marine aquaculture, offshore wind, ocean renewables, and crude oil production. Additionally, we explored country-specific scales for these emissions and discussed points for future research to address the existing gaps. By gaining a better understanding of emissions over the oceans, policymakers could prioritize policy measures for achieving emission reduction goals and promote sustainable ocean development.

Under the background of marine strategy and clean energy strategy, China has carried out large-scale construction around marine ranching and offshore wind farms and made great achievements. However, the problems such as high project cost, the fragmentation of marine habitats and maritime conflict are becoming increasingly prominent, which have led to the test and exploration of integrated development of offshore wind farms and marine ranching at home and abroad. Based on the analysis of relevant research and test work at home and abroad, suggestions are put forward for the current situation of integrated development of offshore wind and animal husbandry, as well as the difficulties and challenges in economic and policy feasibility, site selection and planning, fish species selection, supporting equipment development, ecological impact assessment (noise, electromagnetic field, base interference, heavy metal migration, etc.), etc.

Blue carbon is the carbon storage in vegetated coastal ecosystems such as mangroves, salt marshes, and seagrass. It is gaining global attention as its role in climate change mitigation and local welfare growth. However, a global assessment on the long-term spatiotemporal sustainable development status of blue carbon has not been conducted, and the relations among blue carbon ecosystems, driving forces for climate change mitigation, and socioeconomic interventions for development capacity on a global scale are still unclear. Here, we constructed a blue carbon development index (BCDI), comprising three subsystems: driving force, resource endowment, and development capacity, to assess the sustainable development level of 136 coastal countries' blue carbon over 24 consecutive years and explore the relationship among subsystems. We further propose a cooperation model to explore the feasibility of global blue carbon cooperation and quantify benefit allocation to specific countries. The results showed an upward trend in BCDI scores with variations in regional performance over the past two decades, and we found a positive correlation between development capacity and blue carbon resource endowment. Based on the scenario simulations of global cooperation, we found that coastal countries could improve the global average BCDI score, add 2.96 Mt of annual carbon sequestration, and generate $136.34 million in 2030 under Global Deep Cooperation scenario compared with the Business-As-Usual scenario.

Climate change has become one of the severe challenges faced by all countries. Carbon neutralization, through "carbon emission reduction" and "carbon sink increase", is a key way to address global climate change. Coastal blue carbon ecosystems, such as mangroves, salt marshes and seagrass beds, are huge and long-term sustainable carbon sinks. Therefore, protecting and restoring coastal ecosystems is one of the operable ways to increase carbon sinks. This paper explored the carbon pool and economic value of typical coastal blue carbon ecosystems in China. Two restored wetlands（Niyu mangrove and Yingwuzhou salt marsh）as examples are used to prove that increasing blue carbon by coastal ecosystems restoration is an effective way to realize carbon neutralization. The research results can provide theoretical basis and data support for coastal ecosystem restoration and the blue carbon trading, and further serve carbon neutralization.

Ninety-four percent of islands claimed by China are uninhabited. Due to the lack of protection awareness in developing and utilizing processes, many island ecosystems have suffered severe damage. The government has made measures to regulate the use of uninhabited islands and sea areas, but that is inadequate. We constructed a model of accounting for the natural resource stock and ecosystem services based on emergy analysis to incorporate the ecological cost into the current national uninhabited island use fee system. We used three uninhabited islands in Shanghai as case studies to elaborate on the valuing mechanism. The results illustrate that emergy analysis is applicable for measuring the ecological value of different ecosystems of uninhabited islands, and the price mechanism combined with the ecological capital cost fundamentally enhances the traditional use fee system within an acceptable increased price. The pricing model provides a powerful tool for sustainable use of uninhabited islands, helps policymaking, and can be extended to other uninhabited islands.

Eco-Civilization Construction has gone through 8 years since it has been included in the "five-in-one" overall layout in the 18th National Congress of the Communist Party of China. As an important part of Eco-Civilization Construction, Marine Eco-Civilization Construction (MECC) has also made great achievement in China. This paper was the first attempt to evaluate the performance of Marine Eco-Civilization Construction at county scale. Selecting 20 specific indicators from six subsystems, including resource, ecology, culture, governance, economy and society, we developed an evaluation system for MECC. With the combination of analytic hierarchy process (AHP) and the entropy method, we measured the MECC performance of all 32 coastal counties in Zhejiang Province from 2010 to 2016 and calculated the coordination degree among six subsystems. Temporally, the performance level of coastal districts and counties in Zhejiang was increased steadily, and spatially, the coordination degree however was relatively low in some counties indicating the spatial discordance. Our study could provide important insights for further promoting MECC in China at local scale as well as for other coastal regions' sustainability.

The bay area is a crucial land–sea junction zone containing essential urban clusters while receiving extremely complex internal and external disturbances that challenge more on its resilience management. However, a sound management tool based on the bay area’s resilience is widely lacking due to the difficulty of unifying resilience indicators and quantifying resilience relationships between regions. This paper tries to establish a comprehensive resilience index for coastal bays from four major resilience-related dimensions, namely, physical structure, social development, ecological environment, and hazards, and applies it into the three major developed bay areas in China. A coupling coordination degree model was used to further reveal the resilience development and its internal coordination by temporal and spatial differences. The results show that the index could clearly reveal the resilience changes from the year 2000 to 2020 of the three bays with the common key drivers of socioeconomic development. It also explains the resilience changes among three bay areas through analyzing synergistic and conflict relationships between the four sub-resilience systems.

Climate change has become a great challenge for humanity. However, the current climate change mitigation measures, primarily concentrate on land, more or less neglecting the vital role of the ocean-based solutions. While the ocean is a crucial regulator of the global climate, ocean-based solutions could also play an essential role in climate change mitigation and policymaking. This paper developed an Ocean-based Solutions Carbon Reduction Assessment Model (OSCRAM) that addresses coastal ecosystems, ocean energy, marine transportation, fishery, and seabed to estimate the oceanic contribution to climate change mitigation. It has been applied to evaluate the capacity of carbon emission reduction through oceans in China. We found that the total contribution for carbon emission reduction was about 6.86 Tg CO2 per year, and it may reach 139.39 Tg in 2030 under the target scenario. The results indicated that the ocean has huge potential to reduce carbon emissions. The development of marine energy and low-carbon marine shipping may have more potential for emission reduction in China, and the government should also protect and restore coastal wetlands for their enormous carbon storage. It can also provide a reference for the globe and other nations in achieving emission reduction goals.

自海洋生态文明提出以来,从中央到地方,各个沿海省市已开展了全方位的海洋生态文明理论与实践工作.本文在自然-社会-经济复合生态系统的基础上,构建包含社区、经济、管治、文化、资源和生态6个子系统共34个指标的海洋生态文明建设绩效评估指标体系,采用极值法对数据进行标准化处理,采用主、客观赋权相结合的方法确定指标权重,最终得到2010—2016年浙江省海洋生态文明建设绩效及其变化趋势.结果表明,浙江省海洋生态文明建设水平总体较高,处于快速增长阶段,但存在地区及系统间发展不平衡现象,后续应继续加强生态恢复和资源保护,完善管理体系,加强区域合作.

Over 90% of the world's fisheries have been fully exploited or over-fished. Included is the large yellow croaker (Larimichthys crocea), an important commercial fish species in China whose population was nearly depleted prior to the 1980s. Although overfishing and natural resources collapse present a daunting issue, some studies indicate that improved management strategies could aid in natural stock restoration to prevent depletion. We developed an integrated assessment method grounded on an ecosystem-based approach and deigned an integrated index with three key aspects of habitat suitability, natural population status and government & social interventions, to evaluate the potential restoration capacity of the species in a designated “national aquatic germplasm resource protected area” in Guanjinyang based on a data set spanning 1987 to 2015. The results show that although restoration efforts on research and rehabilitation have increased greatly since late 1990s, the effectiveness stays moderate and the natural population remains near depletion.

China needs to balance between current population pressures and a vulnerable marine environment, creating a national, political outline or management strategy dubbed an ecological civilization construction. The nation's effort to protect and maintain a sustainable ocean and address the relevant economic, resource and environmental issues relies on Marine Ecological Civilization (MEC) construction. The quantification of MEC progress is essential to track the management performance and guide the subsequent development and implementation. This study evaluates the performance of China's MEC from 2006 to 2016 based on a comprehensive index system. Our findings are as follows: During 2006-2016, the overall MEC performance score increased from 0.3426 to 0.4850 nationwide. Large space-time variations exist among the eleven coastal regions. The Shandong and Guangdong regions showed relatively good performances, whereas the Jiangsu, Guangxi and Shanghai regions had low scores. A decade long change in MEC scores showed that Hebei achieved the largest increase ratio. Marine management was improved by implementing various conservation strategies by China's government. Marine education and human talent introduction deserve more attention in less developed areas such as Hainan and Guangxi, and poor marine environmental quality was an urgent issue of the Yangtze river estuary economic zone. More accessible marine monitoring dataset are needed to track future space-time progress dynamics towards MEC construction. Our results provide a decade long retrospect of China's MEC achievements, and the quantified evaluation for each coastal region can provide valuable insight to policy-makers.