Assessment of carbon emission efficiency in the Pearl River-Xijiang economic belt over the past 15 years and exploration of improvement opportunities

Carbon Emission Efficiency (CEE) serves as a crucial metric for assessing regional economic development and carbon mitigation. Enhancing CEE promotes synergy between economic growth and emission reduction, accelerating socio-economic green transformation. As China's first cross-basin ecological civilization pilot zone, the Pearl River-Xijiang Economic Belt (PXEB) exhibits significant upstream-downstream disparities in CEE, reflecting varying capacities to balance carbon reduction, economic growth, and ecological conservation. Investigating CEE determinants (including socio-economic and policy factors) is vital for designing spatially differentiated strategies aligning basin-wide sustainability with local development needs. Using 2005–2020 panel data from 67 PXEB districts, this study applies the SBM-DDF model and the Global Malmquist-Luenberger index to measure CEE, with GTWR modeling analyzing six influencing factors. Key findings: (1) During 2006–2020, PXEB's CEE showed fluctuating growth, with upstream areas having greater improvement potential. Upstream inter-county disparities constituted the primary source of regional imbalances. (2) CEE transition dynamics are spatially heterogeneous, where neighboring areas' improvements promote local upward shifts and curb declines within specific regional typologies. (3) Economic development level is the strongest driver of CEE improvement, while energy intensity constitutes the main barrier to enhanced CEE in the PXEB. This study comprehensively evaluates PXEB's CEE through dynamic-static dimensions, systematically examines drivers' spatiotemporally heterogeneous impacts, and clarifies mechanisms linking factors like population density to CEE, offering scientific support for tailored emission reduction policies. • Carbon emission efficiency and its potential for enhancement in PXEB were assessed. • The imbalance of CEE between upstream and downstream counties is prominent. • Enhanced upstream carbon governance critically improves CEE in the PXEB. • The evolution of CEE in the PXEB has obvious spatial spillover effects. • The drivers of CEE exhibit significant spatio-temporal non-stationarity in the PXEB.