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Carbon storage in terrestrial ecosystems plays a vital role in climate control. However, urban expansion and damage to natural areas, especially the rise of megalopolises, have affected carbon storage. To mitigate this damage, various policies have been established by international, domestic, and local governments. This study focuses on the establishment and management of environmental protection areas and analyzes their impact on carbon storage. The study targets the cities of Gyeonggi-do province, South Korea, which make up a representative megalopolis, and the effectiveness of protected areas was analyzed by typifying the cities based on the proportion of available development areas and environmentally protected areas. In this study, the SLEUTH (Slope, Land-use, Excluded Area, Urban, Transportation, Hillshade) land-use change model was used to predict future land-use changes, and carbon storage was estimated using the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) Carbon model. When operating the model, we tested a control group scenario that only preserves the water zone, a scenario that preserves the legally protected areas, and a scenario that protects the areas with high environmental value. There are two significant effects of setting up protected areas: First, the “development inhibition effect” of reducing the development area itself. Second, the “development replacement effect” of moving development to relatively low environmental value areas. These two effects differ depending on the availability of development areas, with “development replacement effects” prominent in areas with high development availability and “development inhibition effects” predominant in areas with low development availability. Future policies for setting up and managing protected areas can be used in megalopolis in conjunction with policies focusing on securing the area of carbon sinks.

Analysis of the correlation between vegetation greenness and climate variable trends is important in the study of vegetation greenness. Our study used Normalized Difference Vegetation Index-3rd generation data from the Advanced Very High-Resolution Radiometer - Global Inventory Modeling and Mapping Studies (AVHRR-GIMMS NDVI3g), land cover data from the Climate Change Initiative (CCI-LC), and climate data from the Climatic Research Unit global time series (CRU TS) of climate variables (temperature and precipitation, solar radiation) over the past 33 years. First, we estimated the overall trends for vegetation greenness and climate variables over five time periods. Second, we subjected the data to correlation, regression, and residual analyses to detect correlations between vegetation greenness and different climate variables. Third, we extracted trends and correlation results by primary land cover types for each climate zone. Our study was focused at the global scale, and findings indicate that the largest decreasing trend of vegetation greenness and grasslands occurred in the mid-latitude regions of the Northern Hemisphere and in parts of South America, Africa, Saudi Arabia, and south and northeast Asia. In particular, the cold climatic zones of forest (36.6%), cropland (36.6%), and grassland (14.1%) suffered significant decline in vegetation greenness. Anthropogenic activities are mainly responsible for declining vegetation greenness particularly in northern Africa, central and western Asia. However, residual analysis shows an increase in vegetation greenness in some parts of western Europe, southern Australia, and the northern part of South America. The study also identified temperature and precipitation as the main factors responsible for controlling vegetation growth. Hot-spot areas with the largest temperature increases were found in the Amazon, Central America, southern Greenland, east Africa, south-east Asia, and other areas. However, temperatures decreased in the western part of South America, Angola, the Philippines, Indonesia, and Papua New Guinea. Precipitation decreased the most from March to May over most parts of the world with high correlation (r = 0.88) in Russia Canada, northeast Asia, and central Africa. In general, climate factors were the principal drivers of the variation in vegetation greenness globally in recent years.

The threat of fine particulate matter (PM2.5) is increasing globally. Tackling this issue requires an accurate understanding of its trends and drivers. In this study, global risk regions of PM2.5 concentrations during 1998–2016 were spatiotemporally derived. Time series analysis was conducted in the spatial relationship between PM2.5 and three socio-environmental drivers: population, urban ratio, and vegetation greenness that can cause changes in the concentration of PM2.5. “High Risk” areas were widely distributed in India and China. In India and sub-Saharan Africa, the increased overall population was strongly correlated with PM2.5 concentrations. Urban ratio increased in both developed and developing countries. A “decoupling” phenomenon occurred in developed countries, where urban expansion continued while PM2.5 concentrations decreased. Vegetation greenness and PM2.5 were strongly correlated in High Risk zones. Although urban expansion and population growth generally reduce vegetation greenness, developed countries reduced PM2.5 while maintaining greenness, whereas developing countries increased PM2.5 with decreasing greenness significantly in High Risk regions. Ultimately, economic and national growth should occur without increasing PM2.5 concentrations. Recent cases from Europe and the eastern United States demonstrate that this is possible, depending on the development pathway.