Spatiotemporal Imbalance of Carbon Balance Pressure in Sichuan–Chongqing: Anthropogenic Emissions vs. Vegetation Sinks and Their Explanatory Factors

Regional green development requires balancing anthropogenic carbon emissions (CEs) with vegetation carbon sequestration (VCS). Using the CASA model and plant photosynthesis equation, we estimated VCS from net primary productivity (NPP) and proposed a Carbon Balance Pressure Index (CBPI) to quantify the imbalance between carbon sources and sinks. Spatial analysis and a geographic detector were applied to examine influencing factors of CBPI across Sichuan–Chongqing from 2001 to 2017. Results show that CE increased by 178%, while VCS rose by 27%. Regional CBPI thus enhanced from 0.35 to 0.76, aligning with CE trends. The CBPI presented a clear west-low (0–0.2, except Panzhihua), center-high (peak 3.1 in Chengdu), moderate-east (0.1–0.8) pattern. Geographic detector reveals that economic development and urbanization accounted for 80% of CBPI heterogeneity, followed by transportation (65%). Energy-intensive industries dominated developed areas, while construction-land expansion prevailed in developing regions. This study underscores region-specific emission-sink pathways and provides an empirical basis for differentiated low-carbon strategies in similar rapidly urbanizing regions in China.