How do the external drivers and internal synergies contribute to NOX reduction and carbon mitigation in economic systems? Evidence from a large economy

Air pollutants and carbon dioxide (CO 2 ) shows synergistic reduction potential. However, the synergistic mechanism between pollutants and CO 2 emissions remains unclear on network structure, sectoral interactions, and system evolution characteristic. This research takes China’s economic sectors as a case study, identifies the external drivers affecting nitrogen oxide (NO X ) and CO 2 emissions employing the structural decomposition analysis, and assesses the structure of NO X and CO 2 emission networks and their emission exchange mechanism among sectors in 2012, 2017 and 2020 applying the flow-based and information-based ecological network analyses. The findings reveal: (1) Direct emission intensity, technology level, and composition of final demand categories drive the reduction of 110.30% NO X and 44.54% CO 2 emissions, while final demand per capita, population, and consumption structures drive emission growth. (2) Sector Petroleum extraction and Power and heat production are the major control (flow output) sectors of NO X and CO 2 emission-flow networks, and optimizing their control measures is crucial for reducing emissions of the whole network system. Sector Services is the key dependent (flow input) sector. Mutualism relationships in both the NO X and CO 2 emission-flow networks are mainly related to energy production and conversion sectors. (3) The NO X and CO 2 network systems are both operating in a state of low aggregation, high dispersion from 2012 to 2020. CO 2 systems have lower robustness values than NO X systems and their system resilience is relatively weaker. Differentiated emission reduction schemes for variously structured emission-flow networks should be encouraged, and measures related to carbon emission reduction are prioritized in synergistic control. • External drivers and internal synergies of NO X and CO 2 emissions are investigated. • The structure, state and pairwise interactions of NO X and CO 2 networks are explored. • NO X and CO 2 networks are in a state of low aggregation and high dispersion. • Systems resilience of CO 2 emission network is weaker than that of NO X network. • Measures related to carbon emission reduction are prioritized in synergistic control.