Abstract: The Beijing-Tianjin-Hebei (BTH) urban agglomeration is characterized by rapid urbanization and coordinated development. It is important to clarify the changes of regional carbon sources and sinks, and to reveal the state and dynamics of regional carbon budget balance for achieving the “dual carbon” target and regional sustainable development. In this study, we used the static and dynamic analysis methods of carbon source-sink matching relationship to analyze the change of carbon budget balance state and the evolution of matching relationship in the BTH region. The results showed that carbon emissions due to human activities were higher than carbon sequestration from natural vegetation in the BTH region, indicating an obvious carbon deficit. The carbon balance index remained at 14%-27%. The net carbon emissions increased from 254.67 Mt in 2000 to the highest value of 678.08 Mt in 2013, and then tended to be stabilized as 668.98 Mt in 2019. The carbon balance matching varied greatly among the cities. From the static perspective, Zhangjiakou and Chengde were in “high carbon sequestration and low carbon emission” type in 2019, with an obvious carbon sink function. Among the other cities, six were in “low carbon sequestration and high carbon emission” type, four in “low carbon sequestration and low carbon emission” type, and one in “high carbon sequestration and high carbon emission” type. From a dynamic perspective, the 20-year evolution trajectory of carbon source-sink matching relationship in the BTH region was at an “emission increase-sink increase-unsustainable” type, and the evolution trajectory of a single year was highly variable. Among the various cities, the 20-year evolution trajectory of carbon balance matching relationship of Beijing was at an “emission increase-sink increase-sustainable” type, and its development path was more in line with the carbon neutrality target and low-carbon transition requirements.

Key words: carbon neutrality, carbon emission, carbon sequestration, four-quadrant method, dynamic evolution