Divergence in International Shipping CO2 Emissions across Economies from an Export Perspective.

International shipping plays a vital role in global trade but remains a significant source of CO2 emissions, posing challenges for global climate goals. This study systematically investigates the evolution of shipping CO2 emissions associated with countries' maritime export trade from 1995 to 2021 using a trade-driven approach and evaluates disparities in national emission patterns. Results show a shift from a high-income dominance toward a more balanced distribution, with growing contributions from upper-middle-income and emerging economies. While the global average GDP-normalized shipping emission intensity declined by 33.6% during the study period, substantial variations exist across economies. Middle-income countries once exhibited nearly twice the GDP-based emission intensity of high-income economies, but this gap has narrowed with economic diversification. Per capita shipping emissions saw only modest growth globally, yet differences across countries remain pronounced. High-income countries account for over half of global emissions despite representing only 15% of the world's population, maintaining persistently above-average per capita levels. Major emitters─including the United States, Australia, Brazil, and China─show striking contrasts: Australia records both GDP- and population-normalized intensities well above the global average, whereas China's values fall below it, underscoring structural inequities in the distribution of the shipping-related carbon burden. These findings highlight persistent disparities in maritime emissions and underscore the need for a differentiated, multimetric framework to guide equitable responsibility allocation.