Impacts of cross-regional population migration and agglomeration on carbon emissions in China

Urbanisation and population agglomeration have significantly increased China's CO2 emissions. Migration has altered the quantity and spatial distribution of CO2 emissions, yet these changes have not been quantified. This study used a counterfactual analysis to determine the impact of migration on CO2 emissions. Specifically, we used a multi-scale geographically weighted regression to estimate the marginal effects of net immigration on CO2 emissions, an environmentally extended multi-regional input-output model to determine how migration impacts the CO2 emissions of inflow and outflow regions as well as the regional transfer of CO2 emissions, and structural path analysis to identify key sectors and their emission paths. The results indicate that population emigration from less-developed regions was primarily responsible for reducing CO2 emissions. Upon migration to urban agglomeration areas, individuals chose cleaner fuels and used public services more frequently, which resulted in a significant reduction in the intensity of local emissions. Furthermore, migration led to a narrowing of spatial disparities in indirect emission reductions. Provinces in eastern and north-eastern China were less affected by indirect CO2 emissions caused by immigration. Additionally, the eastern and central regions exhibited 'regional agglomeration' and 'self-circulation' in the emission paths of key sectors.