Optimizing land cover planning for carbon neutrality: Policy insights from scenario-based vegetation carbon sink assessment in the Guangdong–Hong Kong–Macao Greater Bay Area, China

Mitigating national climate change requires achieving carbon neutrality, necessitating innovative land cover strategies that reconcile economic development with enhanced carbon sinks, particularly in rapidly urbanizing megaregions such as the Guangdong–Hong Kong–Macao Greater Bay Area (GBA) in China. This study developed a novel assessment framework that integrates Multi-Objective Programming (MOP) land cover simulations with a Carbon Neutrality Effect (CNE) matrix and a neighborhood proxy method. This framework provides a quantitative evaluation of vegetation carbon sink dynamics resulting from land cover transitions during 2020–2060 under four scenarios: economic development first (ED), carbon neutrality first (EC), sustainable development (EDC), and natural development (EN). Model validation achieved high accuracy (Kappa coefficient=0.77, Overall Accuracy (OA)=0.84). Projected land cover changes revealed distinct transition patterns. Specifically, under the ED and EN scenarios, land cover changes will dominate by the expansion of urban area at the losses of grassland and crop land; under the EC scenario, the new forested land is primarily from crop land and grassland; and under the EDC scenario, urban area and forested land will achieve simultaneous expansion. Moreover, this study found the net vegetation carbon losses of 51.43×10 10 and 274.54×10 10 g C under the ED and EN scenarios, respectively, undermining carbon neutrality. In contrast, there will be a significant net carbon gain (64.52×10 10 g C) under the EC scenario. Crucially, the EDC scenario demonstrates a viable balance, minimizing vegetation carbon loss (7.00×10 10 g C) while substantially enhancing both socioeconomic benefit (1.34×10 12 CNY/a) and vegetation carbon sink benefit (0.15×10 12 CNY/a). This study underscores the critical role of optimized land cover planning in fostering synergistic economic growth and carbon neutrality. The findings provide actionable insights for the implementation of ‘Dual Carbon’ strategy in the GBA and serve as a valuable reference for sustainable land management in climate-vulnerable coastal megacities worldwide.