This paper is the result of environmental geological survey engineering.

Objective Against the background of global warming, this study aims to investigate the spatial and temporal evolution of carbon stocks in the Beijing-Tianjin-Hebei Urban Agglomeration region from 1990 to 2020, and to reveal the mechanism of spatial and temporal heterogeneity in the impacts of factors such as the natural environment, socio-economics, and landscape patterns on the carbon stocks, with a view to providing a scientific basis and data support for the realisation of the goal of carbon neutrality in the region. Research Methods In this paper, the Beijing-Tianjin-Hebei region is taken as the research object, and the change of carbon stock in the region between 1990 and 2020 is evaluated by using the InVEST model, the spatial correlation analysis is applied to verify the spatial autocorrelation characteristics of carbon stock in the study area, and the impacts of the factors of the natural environment, socio-economics, and landscape pattern on the carbon stock are analyzed by the spatial and temporal geographically weighted regression model (GTWR).

Results The total carbon stock of the four phases in the Beijing-Tianjin-Hebei region from 1990 to 2020 is 17.20×10⁸ t, 17.57×10⁸ t, 17.92×10⁸ t and 17.91×10⁸ t in order, and the ecosystems behave as carbon sinks, with the value of carbon stock increasing by about 4.16%, and the high-value area of the carbon stock is mainly concentrated in the line of the Taihangshan-Yanshan Mountains, whereas the low-value area is located in the North China Plain. There is a significant positive correlation between carbon stocks in neighboring geographic units at the county scale, with overall high - high and low - low aggregation. The spatio-temporal geographically weighted regression model (GTWR) analysis showed that there was significant spatio-temporal heterogeneity in the effects of factors on carbon stocks, and the factors that had a positive effect on the carbon sequestration capacity of the Beijing-Tianjin-Hebei region were, in order of magnitude, elevation (0.73), NP (0.17), NDVI (0.18), IJI (0.15), PARA_MN (0.14), and PD (0.06), and negative effect factors were population density (−0.12), temperature (−0.11), PRD (−0.04), and GDP (−0.03) in order. Carbon emission reduction strategies should be based on the enhancement of the carbon sequestration capacity of the natural ecosystem and the reduction of the negative impacts of anthropogenic activities on the carbon stock in order to integrate and formulate differentiated countermeasures according to local conditions.

Conclusion The optimization of carbon sequestration function needs to comprehensively consider the causal links between natural and socio-economic factors, and achieve the coordinated development of ecological, economic and social benefits through scientific planning and policy guidance. This study provides a scientific basis for the formulation of scientific ecological protection and carbon emission reduction policies, and helps the Beijing-Tianjin-Hebei region to realize the goal of "double carbon".