Interpreting conflicting sustainability indicators: The paradox of coupling and coordination in Hainan's urban-ecological system

Abstract

Sustainability indicators are intended to guide environmental policy, but what happens when they tell conflicting stories? This study confronts this critical governance paradox through an in-depth case study of Hainan Island, a globally significant ecological hotspot undergoing intense urbanization. We employed the Coupling Coordination Degree (CCD) model to analyze two decades (2000–2020) of urban and ecological data, quantitatively assessing both the intensity of their interaction (coupling degree) and its quality (coordination degree). Our results reveal a stark “separation phenomenon”: while the coupling degree remained exceptionally high (>0.94), suggesting a tightly integrated system, the coordination degree collapsed from a healthy 0.724 to a state of imbalance at 0.544. This divergence exposes a dangerous phase of “exploitative coupling,” where urban expansion efficiently consumed natural capital, creating a misleading picture of systemic health. This research provides a crucial, actionable lesson for environmental management: coordination, not mere coupling, is the true compass for sustainability. Our findings directly inform an adaptive governance framework that uses indicator divergence as an early warning trigger for policy intervention. We argue for a fundamental policy shift towards fostering “synergistic coupling,” offering a new model for navigating the complex trade-offs between development and conservation in sensitive regions worldwide.