Abstract
BACKGROUND: The transportation sector, as a significant contributor to global CO(2) emissions, demands urgent attention to align its decarbonization with national carbon neutrality agendas. Existing research disproportionately focuses on quantifying TCE (transportation CO(2) emissions) and mapping their spatio-temporal distributions. However, the evolutionary trajectories and sequential peaking dynamics of TCE across different national contexts remain unclear. To address this question, this study was conducted. RESULTS: A global comparative analysis of 115 countries was conducted, establishing a four-stage TCE development typology through three metrics: TCE intensity (A), per capita TCE (B), and total TCE (C). The analysis revealed a universal A → B → C peaking sequence, with Stage II (A to B transition) exhibiting a significantly prolonged duration (mean = 8.37 years) compared to Stage III (B to C transition; mean = 2.12 years). Developed economies predominantly occupy Stage IV, while developing countries cluster in Stage II and Stage III. Regionally, North American countries demonstrated extended durations in both stages, exceeding global averages. Regression analysis indicated that socioeconomic indicators have limited explanatory power in predicting stage durations, underscoring the individualized nature of TCE progression across nations. CONCLUSIONS: This study contributes by revealing the unified and diverse peak patterns of three core TCE indicators at national levels, while addressing a critical gap in global emission reduction strategies through cross-economy analysis. The findings confirm a predictable evolution in TCE across most nations but highlight significant variations between developed and developing economies. The prolonged duration of Stage II compared to Stage III suggests a more challenging transition phase for many countries. Moreover, the limited influence of standard socioeconomic metrics on stage durations emphasizes the need for nuanced, country-specific approaches to emissions transitions. The study proposes targeted TCE reduction measures differentiated by development stage and transportation sub-sector, providing scientific guidance for policy formulations.