# Towards a Single Integrative Metric on the Dynamics of Social-Environmental Systems
## 3 Empirical Evidence for IMoSES Applications
As expected, the steady increases in IMoSES for the six PEs in China corresponded well to the accession of China to the World Trade Organization (WTO) in 2001 [25; 30]. The differences among Chinese PEs might be further explained by various policies of the central government, including the drive to promote economic development in China's western regions [55; 56]. Clearly, institutional changes (including new policies, cross-country geopolitical conflicts, etc.) can have strong and lasting effects on IMoSES [29; 30; 57]. More importantly, the sensitivity of IMoSES to institutional changes further suggests IMoSES is a useful measure for quantifying SES dynamics. For the second question (i.e., Does IMoSES provide any new insights from its three components that describe social, economic, and environmental systems? ), we can compare IMoSES with three dominant components at PE and sub-region levels: GDP\({}_{\text{PC}}\), POP\({}_{\text{d}}\) and HANPP (Equations (3)-(5)). In this regard, we compared the long-term mean (SD) of IMoSES with GDP\({}_{\text{PC}}\), POP\({}_{\text{d}}\) and HANPP for the 18 PEs (Figure 4). The means and variations of IMoSES are very different from those of any three components among the PEs. By definition, IMoSES has a positive relationship with GDP\({}_{\text{PC}}\) and HANPP, but a negative relationship with POP\({}_{\text{d}}\) (Equations (1)-(4)). These relationships appear consistent, albeit with large differences among the PEs. Overall, Turkey, Kazakhstan, and Mongolia are the top three PEs for their IMoSES, which matches well with their relatively high HANPP (Figure 4d) and low POP\({}_{\text{d}}\) (Figure 4c). However, the high IMoSES for Kazakhstan is due to high GDP\({}_{\text{PC}}\) and low POP\({}_{\text{d}}\); whereas Mongolia and Turkey have relatively low GDP\({}_{\text{PC}}\). Among the PEs with low IMoSES, GDP\({}_{\text{PC}}\) and HANPP are comparatively lower while POP\({}_{\text{d}}\) is high. Increased IMoSES values can arise from rising GDP\({}_{\text{PC}}\) and HANPP and declining POP\({}_{\text{d}}\) over long time periods, except in times of armed conflict or a pandemic. In conclusion, we are convinced that IMoSES provides insights that none of the three components alone do. More importantly, the metric provides policymakers with some idea about the dynamics of each of the pillars, which can be used to identify SES dimensions requiring additional research and perhaps policy attention to move PEs toward improved and more sustainable IMoSES. For example, lessons from the different rebounding processes of Central Asian countries and Mongolia could identify constraining mechanisms in slowly recovering countries after the collapse of the USSR (Figure 3). To address the utility of IMoSES in our third question (i.e., Is IMoSES meaningful when compared with other independent measures of SES properties? ), we examine its relationships with other integrative measures of SES: (1) PDSI, which is an effective measure of environmental stress, and (2) HDI, which is a robust indicator of social conditions (Figure 5). We caution that PDSI is calculated with some common variables (e.g., temperature and precipitation), suggesting that IMoSES is not completely independent of PDSI. Overall, IMoSES increases with PDSI in dry-to-normal conditions (PDSI! 0) and decreases in normal-to-wet conditions (PDSI? 0) (Figure 5a). The changes in IMoSES with PDSI are similar to the environmental Kuznets curve depicting the relationship between environmental degradation and economic development [58]. IMoSES rises to its peak where water stress is minimal (i.e., not too dry or wet), after which, IMoSES declines as conditions become wetter (Figure 5a). This behavior suggests that deviations from the average PDSI for a region are negatively associated with SES functioning. More importantly, we used a quadratic model to estimate the upper envelope of values in the scatterplots--the potential maximum IMoSES for ADB countries.