Divergent futures for critical ecological areas: How climate pathways reshape the roles of ecosystem integrity,...

Critical ecological areas (CEAs) are essential for maintaining resilient ecosystems by providing vital services and regulatory functions. However, existing approaches for identifying CEAs predominantly rely on historical patterns, often overlooking their dynamic evolution under future climate scenarios, which limits the development of proactive adaptation strategies. To address this gap, this study develops a forward-looking assessment by exploring the future evolution of CEAs in the Yellow River Basin under four representative Shared Socioeconomic Pathways (SSPs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6), within the Ecosystem Integrity-Multifunctionality-Stability framework. Results demonstrate that by 2050, the spatial patterns of ecosystem integrity (EII) and multifunctionality (EMI) are projected to remain relatively stable. In contrast, areas of high ecosystem stability (ESI) expand as emission intensity increases, shifting towards the central basin and extending northward. Consequently, CEAs are also concentrated in the midstream region, exhibiting a northward trend under future climate scenarios. Lower emission scenarios, such as SSP126, are associated with the conversion of other areas into CEAs, while SSP245 plays a more significant role in maintaining and enhancing the quality of existing CEAs. Therefore, balancing ecological protection and economic development is crucial in future climate scenarios. Additionally, high-quality CEAs are most strongly associated with EII, although this relationship weakens as emission intensity increases. In regions showing consistent improvement across multiple scenarios, higher ESI is observed, with EMI being the second strongest association, while EII is generally lower compared to other areas. These findings emphasize that improving CEA quality is not dependent solely on enhancing a single attribute but requires a comprehensive strategy that safeguards landscape integrity while enhancing stability. Improving high-quality CEAs will promote sustainable ecosystem functions and meaningfully contribute to achieving sustainable development goals.