The impact of climate change and human activities to vegetation carbon sequestration variation in Sichuan and Chongqing.

Exploring the vegetation carbon cycle and the factors influencing vegetation carbon sequestration in areas with complex plateau-basin topography and fragile ecosystems is crucial. In this study, spatial and temporal characteristics of carbon sequestration by vegetation in Sichuan and Chongqing from 2010 to 2020 and the influencing factors were investigated through simulations of net primary productivity (NPP) using the modified Carnegie-Ames-Stanford approach (CASA) and the Thornthwaite Memorial (TM) model and using chemical equations of photochemical reactions. The results indicated that: The spatial distribution of carbon sequestration capacity (CSC) trends showed an increase in the east (the most prominent increased trend along the mountainous areas of the basin) and a decrease in the west (western Sichuan plateau). Differences exist in the impact factors of CSC in different regions. In the basin margins and mountainous areas, where the proportion of forests was high, a combination of climate change and human activities contributed to the increase in CSC. The relatively warm and humid meteorological conditions in the hinterland of the basin were more conducive to the increase in CSC, and climate change also affected the region more significantly. In contrast, in the relatively high altitude of western Sichuan, controlled human activities were the key to improving CSC. The results of the study contribute to the understanding of the basic theory of vegetation carbon cycle in areas with complex plateau-basin topography and fragile ecosystems, as well as to provide suggestions for ecological shelter construction and ecological restoration in the upper Yangtze River.

The Russia-Ukraine war disproportionately threatens the nutrition security of developing countries.

While the ongoing Russia-Ukraine war threatens global nutrition security, the magnitude and extent of its impact remain underexamined. Here we show that, with the lowest level of war duration, severity, sanction, and countries involved, the direct and indirect impacts of the war and sanctions could newly place 67.3 million people (roughly equals the total population of France) in undernourishment and 316.7 million people (roughly equals the total population of Bangladesh and Russia) suffering from extreme national food insecurity. Approximately 95% of the affected population are from developing countries, highlighting the vulnerability of food supply in these countries. Both the undernourished population and its inequality across countries will substantially grow, if war duration and severity increase. If the war is prolonged to early 2024, future agricultural growth cannot fully offset the negative impacts, and global hunger will still very likely exacerbate. We conclude that targeted measures should be placed in developing countries and their vulnerable populations to reconstruct a just, healthy, and environmentally sustainable food system. Supplementary Information: The online version contains supplementary material available at 10.1007/s43621-022-00112-8.

The impact of urbanization and consumption patterns on China's black carbon emissions based on input-output analysis and structural decomposition analysis.

Urbanization in China has dramatically increased from 39.10 in 2002 to 58.52% in 2017. Studies have discussed the impacts of urbanization and its corresponding changes in consumption patterns on carbon dioxide emissions; however, little is known about their impacts on black carbon (BC). Therefore, we collected data on the BC emissions of various sectors to calculate the consumption-based BC emissions in China, and we used an input-output analysis (IOA) and structural decomposition analysis (SDA) to explore the impacts of urbanization and changes in consumption patterns on BC emissions from 2002 to 2017, focusing on sectoral BC emissions. The total BC emissions of various sectors first increased and then decreased. BC emissions increased from 1083.47 in 2002 to 2550.83 Gg in 2012. They were then reduced to 2478.63 Gg in 2017. Additionally, with the rise in the urbanization rate, household consumption BC emissions increased from 446.18 in 2002 to 1080.12 Gg in 2017. Urban consumption, rural consumption, and BC emission intensity were the three main contributing factors to household consumption BC emission changes. Transport, storage, postal, and telecommunications services (TSP); farming, forestry, animal husbandry, and fishery (FFA); and residential and other industries (RES) contributed the most to the urbanization-related BC emission increase. In particular, the TSP sector contributed the most to the BC emission increase because of the increasing TSP needs related to urbanization. Therefore, it is necessary to formulate mitigation policies for the TSP sector.

[Analysis of Transport Pathways and Potential Sources of Atmospheric Particulate Matter in Zigong, in South of Sichuan Province].

Atmospheric particulate matter pollution in Zigong City in southern Sichuan is quite severe. The average concentrations of PM10 and PM2.5 from 2015 to 2018 were (95.42±9.53) µg·m-3 and (65.95±6.98) µg·m-3, with an obvious trend of decline. The concentrations of PM10 and PM2.5 in winter were much higher than in other seasons, with the highest average concentrations being(138.08±52.29) µg·m-3 and (108.50±18.05) µg·m-3 in January, respectively, whereas in summer, the average concentrations were lowest. The average ratio of PM2.5 to PM10 is 69.12%, and the ratio in winter is about 1.17 times that in summer; thus, PM2.5 is mainly responsible for the air pollution. To explore the potential sources of fine particulate matter (PM2.5) in Zigong City and the pollution contributions of different sources in different seasons, the concentration of PM2.5 in Zigong and the daily trajectory after 72 h were calculated and clustered by the combined use of a variety of potential source analysis methods and data. These methods and data included the hybrid single particle lagrangian integrated trajectory (HYSPLIT) model, global data assimilation system (GDAS) meteorological data, potential source contribution analysis (PSCF), and concentration of weight trajectory analysis (CWT). The results showed that the area near Zigong is mostly controlled by southeasterly, westerly, and northwesterly winds in all seasons, and the high PM2.5 concentration is mostly located in the low-wind-speed zone of 0-2 m·s-1. The influence of different seasons and transport routes on PM2.5 pollution in Zigong is significant. In spring, it is mainly affected by short-distance air flow from the west and north; in summer, the pollution mainly comes from the southeast air flow of short-distance transportation; in autumn, it is mainly affected by short-distance transportation air flow from Ziyang, Suining, Chongqing, and Neijiang; and in winter, it is not only affected by the surrounding cities such as Ziyang, Suining, and Neijiang but also by the long-distance transportation air flow from central Tibet. In general, the potential source area of particulate matter in Zigong City is mainly located in the border area between the west of Chongqing and the south of Sichuan. In winter, the main contribution area is at its widest, while in summer, the potential source area is smallest.