Current status and future emission reduction pathways of NOx in China

Understanding the spatiotemporal evolution and regional mitigation potential of NOx emissions in China is critical for designing targeted and effective emission reduction strategies. Using the MAKESENS model, this study first examined NOx emission trends from 2000 to 2020. We then constructed the GDP-NOx Curve (GNC) function to assess provincial responses to economic development. The provincial compliance with the 10 % reduction target of the 14th Five-Year Plan and the future reduction potential were also subsequently evaluated. The Geographically and Temporally Weighted Regression (GTWR) model was further applied to identify the impacts of seven driving factors across regions. Results show that China's NOx emissions peaked at 2.91 × 10⁷ t in 2012 and have since declined under stringent environmental policies, with eastern provinces reducing earlier and faster than those in the west. The GNCs revealed three distinct patterns: continuous decline, U-shaped, and inverted U-shaped, which were shaped by differences in industrial structure and technological development. More than 70 % of provinces were projected to meet the 10 % reduction target, with northern provinces showing the most significant potential for achieving this goal. We also found that climate mitigation measures can significantly accelerate reductions in emissions. Based on compliance levels, provinces were classified into four groups: highly compliant, compliant, non-compliant, and severely non-compliant. Their reduction potentials were ranked accordingly, and driving mechanisms varied across the groups. These findings advance the understanding of NOx mitigation in China and provide scientific guidance for developing region-specific and outcome-oriented reduction strategies.