As in previous reports and studies, the 2018 EPI shows a positive correlation with country wealth, as measured by per capita GDP. Figure 3-1 illustrates the relationship between EPI scores and wealth. One of the consistent lessons of the EPI is that achieving sustainability goals requires the material prosperity to invest in the infrastructure necessary to protect human health and ecosystems. In a rapidly urbanizing world, it is important to build facilities that deliver improved sources of drinking water, manage wastewater, and mitigate pollution– as through smokestack scrubbers. The inherent tension of sustainable development is that income growth too often comes at the cost of the environment, especially through exploitation of natural resources and unchecked industrialization. The trade-offs between environmental performance and country wealth are also confounded by trade. So far, the spillover costs of trade are poorly captured in most metrics on the environment, though this is an area of active scholarship (Sachs, Schmidt-Traub, Kroll, Durand-Delacre, & Teksoz, 2017). Our pilot metrics further explore current efforts to improve global accounting methods to achieve the Sustainable Development Goals (SDGs) and Targets.
Another enduring finding from the EPI is that the policy objectives constitute distinct dimensions of sustainability. Figure 3-2 illustrates the relationship between sub-scores for Environmental Health and Ecosystem Vitality in the 2018 EPI. While positively correlated, there is substantial variation in both dimensions. The figure suggests tension, as economic growth creates resources to invest in environmental protection while adding to pollution burdens and habitat stress.