Polyethylene terephthalate (PET) is widely used as a primary plastic packaging material in the global socio-economic system. However, research on the metabolic characteristics of the PET industry across different countries, particularly regarding the entire life cycle supply chain of PET, remains insufficient, significantly hindering progress in addressing plastic pollution worldwide. This study employs the Life Cycle Assessment-Material Flow Analysis (LCA-MFA) method to comprehensively analyze the environmental impacts of PET plastics, with a focus on the processes from production to disposal in 12 regions (covering 41 countries) in 2020. By constructing 13 scenarios and analyzing the development trajectory of PET plastics from 2020 to 2030, this study provides scientific evidence and specific strategies for waste reduction and emission reduction measures in the PET industry. Overall, in 2020, the 12 regions (41 countries) consumed 7297.7 kilotons (kt) of virgin PET resin and 1189.4 kt of recycled PET resin; 23% of plastic waste was manufactured into recycled PET materials, 42% went to landfills, and 35% was incinerated. In 2020, the entire PET plastic supply chain emitted approximately 534.6 million tons (Mt) of carbon dioxide equivalent per year, with production emissions accounting for 46.1%, manufacturing stage emissions accounting for 44.7%, and waste treatment stage emissions accounting for 9.2%. Research indicates that under a scenario of controlled demand, resource efficiency improvement and emission reduction are the most effective, potentially reducing carbon emissions by up to 40%.

National parks play a crucial role in promoting the achievement of the Sustainable Development Goals (SDGs) and have become one of the key topics of global concern and discussion. However, it is still unclear whether national park development can effectively enhance the level of sustainable development in local communities related to social and economic dimensions of SDGs. In this study, we constructed an evaluation system based on the SDG assessment indicator framework, to evaluate the sustainable development level of local communities within Hunan Nanshan National Park (NSNP), China. We assessed the development level of various SDG indicators through field visits and structured surveys of local communities inside and around HNNP. We used the entropy method to determine the weight of each indicator and calculated the integrated development index of different communities within and around NSNP. The results indicate the following: (1) The integrated development index of communities within NSNP is generally lower than that of the surrounding communities, but it scores higher in the dimensions of SDG1 and SDG10. (2) The integrated development index within NSNP shows the highest in communities within original natural park, but the lowest in communities within original nature reserve. (3) The structured questionnaire surveys reveal that the primary cause of income decline of residents within NSNP is the restriction on land-use and resource exploitation, while ecological compensation and employment opportunities related to national park management can help improve local livelihoods and thereby promote development level of local communities. This study provides a technical framework for assessing the sustainable development of local communities in Chinese national parks and supports regional planning. It also offers a scientific basis for balancing national park conservation with local community development.