Spatial-temporal differentiation, agglomeration characteristics and coordinated development of greenhouse gas emission efficiency in the Jing-Jin-Ji metropolitan area under the background of regional integration

This study focuses on the greenhouse gas emission efficiency of the Jing-Jin-Ji metropolitan area, employing spatial econometric methods to analyze its spatiotemporal disparities, trend surface characteristics, and agglomeration features. The goal is to examine how effectively the Jing-Jin-Ji integration strategy has improved greenhouse gas emission efficiency within the urban cluster. The study finds that the integration strategy influences emission efficiency in multiple ways: Temporally, the metropolitan area’s greenhouse gas emission efficiency follows a U-shaped trend, with most cities experiencing an initial decline followed by an increase. Spatially, two regions with high emission efficiency stand out—Beijing and the Langfang-Cangzhou-Hengshui area—while other cities show no significant spatial patterns. In terms of trend surface characteristics, both east-west and north-south directions exhibit an inverted U-shaped spatial pattern. Regarding agglomeration, the integration strategy has shifted the distribution of emission efficiency from agglomerated to more random. Beijing, as the core city, has not exerted significant neighborhood or spillover effects on surrounding cities. Therefore, the Jing-Jin-Ji metropolitan area should synergistically improve its greenhouse gas emission efficiency through four key policy mechanisms: establishing a unified coordination body, increasing transfer payments and technology transfer, implementing differentiated industrial policies, and building a cross-regional greenhouse gas information sharing mechanism.