Final answer:
The true statement among the options given is that the EKC turning point estimates for carbon dioxide are greater than those for local air pollutants. This reflects the idea that reductions in CO₂ emissions are more challenging and require substantive changes in energy use and infrastructure.
Step-by-step explanation:
The Environmental Kuznets Curve (EKC) hypothesizes that there is an inverted U-shaped relationship between environmental quality and economic growth. Among the given options regarding EKC turning points and air pollutants, the statement that the EKC turning point estimates for carbon dioxide are greater than for those of local air pollutants (option C) is true. This is because local air pollutants often experience decreases as countries grow wealthier and can afford cleaner technologies, whereas CO₂ emissions have been more persistent, and their reduction requires more significant changes in energy infrastructure and technology.
Moreover, empirical studies suggest that while some progress has been made in reducing overall carbon dioxide emissions in places like the United States, due to anti-pollution policies, reaching the EKC turning point for CO₂ on a global scale in the near term remains uncertain. This is especially challenging as both affluent and low-income countries grapple with the balance between economic growth and environmental protection.