How Urban–Rural Integration Reshapes the Carbon Source‐Sink Balance: A Carbon Offset‐Based Analysis Revealing Pathways and Scale Effects

Abstract

The transition toward carbon neutrality is critically shaped by the management of urban–rural interactions, yet the net carbon consequences of urban–rural integration (URI) remain poorly understood. We systematically assess how URI reshapes the carbon source‐sink balance via an integrated multi‐step analytical approach for 335 Chinese cities (2005–2020). We employ the carbon offset effect (COE)—the net balance between vegetation carbon sequestration (CS) and energy‐related emissions—as a key indicator. We reveal a persistent spatial mismatch between URI advancement and carbon sink capacity, with the national carbon deficit widening from 4.65 to 9.5 Gt CO ₂ and the share of emissions offset by vegetation CS falling from 21.98% to 10.41%. Crucially, we identify two competing pathways: A structural optimization pathway associated with improved carbon outcomes, and a spatial squeeze pathway associated with degraded carbon outcomes. The spatial squeeze pathway dominates, as the standardized coefficient of land urbanization level ( β  = −0.493) is 6.49 times larger in absolute magnitude than that of the structural optimization pathway ( β  = 0.076). The negative association between URI and vegetation COE exhibits scale‐dependent heterogeneity, weakening at higher integration levels and in larger cities, while local synergies between development and carbon sinks are attainable in some key ecological function areas. Our findings reveal the complex relationship between urban–rural transitions and terrestrial carbon dynamics, challenging the assumption that regional integration inherently yields ecological co‐benefits. Incorporating a net carbon‐impact lens into spatial planning is essential to unlock the climate mitigation potential of urban–rural systems, a lesson critical for rapidly urbanizing regions globally.