Contributions of natural systems and human activity to greenhouse gas emissions

In this study, we conducted a literature review of relevant research and then statistically analyzed global greenhouse gas (GHG) emissions from natural systems, including forest fires, oceans, wetlands, permafrost, mud volcanoes, volcanoes, and earthquakes. Drawing on the Global Carbon Project (GCP) report, we also summarized the global anthropogenic GHG emissions. We then compared the global annual GHG emissions from natural systems with those generated by human activity. The results indicate that the global annual GHG emissions range approximately between 54.33 and 75.50 Gt CO2-eq, of which natural emissions account for 18.13e39.30 Gt CO2-eq, with the most likely value being approximately 29.07 Gt CO2-eq. According to the GCP report, the global anthropogenic emissions have increased from 22 Gt CO2-eq in 1990 to 36.2 Gt CO2-eq in 2016. The amounts of natural and anthropogenic GHGs emissions are roughly of the same order of magnitude. Anthropogenic emissions account for approximately 55.46% of the total global GHGs emissions (2016 value), i.e., the ratio of natural to anthropogenic emissions is approximately 0.8. In addition, the annual amount of GHGs absorbed by Earth systems (ocean and terrestrial ecosystems) ranges between approximately 14.4 Gt CO2-eq and 26.5 Gt CO2-eq, with natural system GHG emissions and sinks also having roughly the same order of magnitude. This finding indicates that the GHG emissions generated by human activity exert extra pressure on what is otherwise a self-balancing Earth system.

Spatial association between landslides and environmental factors over Guizhou Karst Plateau,China

Guizhou Karst Plateau is located at the center of the karst region in Asia, where landslides are a typical disaster. Affected by the local karst environment, the landslides in this region have their own characteristics. In this study, 3975 landslide records from inventories of the Guizhou karst plateau are studied. The geographical detector method is used to detect the dominant casual factor and predominant multi-factor combinations for the local landslides. The results show that landslides are prone to areas on slopes between 10° and 35°, of clay rock, in close proximity to gullies, and especially in areas of moderate vegetation, dryland, and mild rocky desertification. Continuous precipitation over 10 days has a great effect on landslide occurrence. Compared with the individual factors, the impact of two-factor interaction has greater explanatory power for landslide volume. The volume of earthquake-induced landslides is predominantly controlled by the interactions of faults and slopes, while that of humaninduced landslides is affected by the interactions of land cover and hydrological conditions. For rainfallinduced landslides, the dominant interactions vary in different regions. In the central karst basin, the interactions between faults and precipitation can explain over 90% of the variations in landslide volumes. In the southern hilly karst region, the interactions between lithology and slope can explain over 71% of the variations in landslide volume and those between fault and land-use can explain 50% of the variations of the landslide volumes in the northeastern mountainous karst region.