A comprehensive empirical study spanning 35 countries between 2003 and 2019 has revealed a consistent positive relationship between public infrastructure development and carbon dioxide emissions. Using an improved entropy method, researchers constructed a composite index of infrastructure incorporating four dimensions—energy, propagation, transportation, and technology—to quantify its scale and quality. This multidimensional measure allowed for a robust examination of infrastructure’s environmental footprint across diverse economies.
The analysis confirmed that, at the global level, infrastructure expansion is currently not aligned with greenhouse gas mitigation goals. Fixed-effects regression models, controlling for economic growth, foreign investment, industrial evolution, population density, and labor force, consistently produced significantly positive coefficients for infrastructure, indicating that more construction correlates with higher CO₂ emissions. This finding held across multiple robustness checks, including alternative dependent variables, regression strategies such as feasible generalized least squares and instrumental variables, and the removal of data from disruptive periods like the 2008–2009 financial crisis.
Sectoral data underscore the scale of the challenge. Thermal power generation emissions rose from 7.5 billion tons in 1990 to 13.2 billion tons in 2020, steel industry emissions reached 2.72 billion tons in 2020 after a 1.5-fold increase over three decades, and cement sector emissions nearly doubled to 2.52 billion tons over the same period. Vehicle-related emissions grew by 75% in 30 years, hitting 5.7 billion tons in 2020. These figures reflect the carbon intensity of foundational infrastructure sectors and the lock-in effect that long-lived assets impose on future emissions trajectories.
The study also explored heterogeneity between Belt and Road Initiative (BRI) countries and non-BRI economies. While infrastructure expansion contributed to higher CO₂ emissions in both groups, the effect was markedly stronger in BRI countries. The likely drivers include weaker economic bases and less mature infrastructure systems, which may rely more heavily on carbon-intensive materials and energy sources.
Beyond direct impacts, the research examined mediation pathways through trade openness and industrial upgrading. Regression models showed that infrastructure fosters trade openness, which in turn increases emissions, confirming it as a valid transmission route. Conversely, industrial upgrading—measured by the ratio of tertiary to secondary sector output—emerged as a pathway that can reduce emissions. The Sobel and Bootstrap tests validated both mediation effects, revealing a nuanced dynamic: infrastructure can simultaneously exacerbate emissions via expanded trade while mitigating them through shifts toward higher-value, less carbon-intensive industries.
The environmental Kuznets curve hypothesis was supported in the data, with economic growth initially increasing emissions before eventually reducing them as economies mature. Foreign investment was associated with lower emissions, suggesting a role for capital inflows in supporting cleaner technologies and practices. Population density and labor force size were positively correlated with emissions, highlighting demographic pressures on environmental systems.
Policy implications drawn from these findings emphasize the urgency of integrating low-carbon principles into infrastructure planning and execution. Establishing green access standards, aligning site selection with environmental constraints, and promoting materials with lower embodied carbon are identified as critical steps. For BRI countries, embedding sustainability into overseas investment and expanding green cooperation fields are seen as essential to curbing the higher emission impacts observed.
Industrial upgrading is highlighted as a strategic lever for emission reduction in the infrastructure sector. Active industrial policies, regulatory support, and technological innovation are recommended to accelerate the transition toward cleaner production and service-oriented economies. By coupling macro-level policy frameworks with targeted technological advancements, governments can harness infrastructure’s economic benefits while steering it toward alignment with global carbon neutrality goals.