Blue carbon ecosystems require conservation and restoration to maximize organic carbon (C_ORG) sequestration to ameliorate greenhouse gas emissions. Salt marshes, mangrove forests and seagrass meadows are all autotrophic and are considered blue carbon ecosystems. Macroalgae and tidal flats are currently not considered blue carbon habitats. Blue carbon ecosystems contribute globally to climate change mitigation and at local and national scales, especially in the provision of other ecosystem goods and services. Financial investment is constrained by large uncertainties in C_ORG dynamics and best practices in restoration, rehabilitation and conservation. Several key emerging perspectives include (1) the fact that groundwater discharge of dissolved carbon is a major pathway of blue carbon loss; (2) allochthonous C_ORG inputs are required to achieve ecosystem carbon mass balance; (3) blue carbon dynamics are enhanced by habitat connectivity and biotic activities; (4) CH₄ and N₂O emissions reduce blue carbon potential; (5) habitat destruction causes blue carbon stock losses, but variable gas emissions; (6) sediment blue carbon stocks are increasing at the poles; and (7) land-use and land-cover changes (LULCC) drive changes in blue carbon stocks and emissions. Further research is needed to clarify the applicability of these emerging perspectives.

As the climate problem becomes more serious, controlling greenhouse gas emissions has become an overarching issue facing all countries. The agriculture sector is one of the main sources of carbon emissions. The measurement of its carbon footprint not only can quantitatively evaluate agricultural greenhouse gas emissions but also provide technical support for low-carbon agricultural construction. However, most reviews focus on the carbon footprint of manufacturing or international trade. Thus, this study selects the agriculture sector and summarizes the literature associated with the carbon footprint. First, this paper analyzes the different definitions of carbon footprint at macroscopic and microscopic levels. Then, Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis is used to summarize the advantages and disadvantages of two main accounting methods, Life Cycle Assessment (LCA) and Input-Output Analysis (IOA). Third, the research on carbon footprint in the agricultural sector is concluded and quantified using CiteSpace. Therefore, this paper gives the implications and prospects of carbon footprint in the agriculture sector. It is necessary to further agree on the definition of carbon footprint and consider other pollutants, water, and energy footprints to optimize agricultural management. Additionally, establishing a carbon footprint accounting model in line with local realities will provide scientific support for developing low-carbon agriculture.

The ending of mangrove concessions for charcoal production in 1998 gave new impetus to mangrove conservation and rehabilitation in Thailand, including the designation of the Ranong Biosphere Reserve (RBR) to protect Thailand’s largest single mangrove ecosystem. Four of the dominant tree species in the RBR were planted as seedlings in single species blocks on a former concession site in 1994: Rhizophora apiculata (Ra) and R. mucronata (Rm); and 1995: Bruguiera cylindrica (Bc) and Ceriops tagal (Ct). Tree growth and natural recruitment of seedlings and saplings were recorded in 100 m² sampled quadrats in each species block in 1999, 2008, 2019 and 2023. All four species exceeded 10 m mean height by 2019 (range 12.1 ± 3.8 m to 19.6 ± 2.3 m), while mean DBH was 7.5 ± 3.4 cm to 9.1 ± 6.9 cm. There was evidence of self-thinning mortality by 2023, especially in the Ra and Bc blocks. Some illegal cutting of Bc trees between 2019 and 2023 further impacted the growth performance of this species, which exhibited a compensatory strategy of self-planting many seedlings. The height and DBH of the four planted species in 2023 were still less than in a mature Rhizophora- and Ceriops-dominated conservation forest area (mean tree height 17.4 ± 6.7 m; DBH 15.1 ± 7.3 cm). However, soil organic carbon (SOC) was high and not significantly different between the monoculture species blocks (525 ± 107 Mg C ha^-1 to 743 ± 31 Mg C ha^-1) and the conservation forest (616 ± 91 Mg C ha^-1). SOC accounted for 74%-90% of the total ecosystem C, which was 650 to 829 Mg C ha^-1 in the planted species blocks and 828 Mg C ha^-1 in the conservation forest. The estimates for plant, soil and ecosystem C are compared with those reported from other natural and planted mangrove sites in Southeast Asia, especially along the Andaman Sea coast. The findings confirm the importance of conserving the few remaining areas of near-primary mangrove forest in this region.

Carbon storage processes in mangrove ecosystems are summarized and future research directions are discussed based on findings from our long-term monitoring studies on Pohnpei Island in the Federated States of Micronesia. On Pohnpei, where coral reef-type mangrove forests dominate, Rhizophora communities maintain their habitat by accumulating mangrove peat at over 5 mm year^-1 in response to rapid sea-level rise, but surface erosion is progressing in communities where the tree density of Rhizophora spp. has declined through succession. However, high-resolution aerial photographs taken by drones have identified trees with reduced vigor even in Rhizophora forests, and if sea-level rise occurs at a rate close to the IPCC's maximum prediction, then Rhizophora forests, which are valuable carbon storage sites due to mangrove peat accumulation, are likely to disappear. The impact of relative sea-level rise is determined by the sum of the rate of ground-level change by the external sediment budget and the rate of ground-level rise with mangrove peat accumulation. In the future, each region will need to conduct its own quantitative evaluation.

Climate change is a major threat to the world. The cause for this global challenge is directly linked to greenhouse gas (GHG) emissions. In order to mitigate climate change, major policies such as reducing GHG emissions are required. Many countries have proposed carbon emission reduction targets at the national strategic level. A crucial issue in achieving the target is low-carbon energy transition, which requires a large amount of clean energy metals as supporting materials. This paper summarizes the latest research results of existing literature on the supply of clean energy metals in achieving the goal of carbon reduction, including the definitions, demand changes, supply capacity assessment, supply risk evolution, supply guarantee and policy system, etc. We point out that further research should be conducted in the following three directions in the future: firstly, strengthen research on the impact of trade and geopolitics on the supply of clean energy metals; secondly, further evaluate the effectiveness of minerals security policies in various countries; finally, broaden the analysis of the clean energy metals supply to encompass the entire industrial chain perspective.