Carbon Footprint of Railway Projects Under the Belt and Road Initiative and the Future Low-Carbon Pathways

The Belt and Road Initiative (BRI) makes headway in constructing railway projects invested by China, yet related environmental impacts are rarely discussed. Here we quantify the carbon footprint of railway project construction (RPC) under the BRI and identify the drivers behind their variations to find possible carbon reduction pathways. Our results show that China-invested overseas RPC in BRI countries induced 2,095.2 Mt CO2 emissions through the global supply chains during 2008-2017. Specifically, 73% of the carbon footprint relies on supply chains in BRI countries, and 27% spills over to other regions serving as the suppliers of global resources. Upgrading key industries' technological levels in BRI countries to China's average level can mitigate the carbon footprint by 77%. Once all industries achieve China's average technological level, nearly 90% of the carbon footprint can be avoided. The findings potentially provide valuable insights into achieving sustainable project construction in cross-regional cooperation and promoting green development of the BRI. The Belt and Road Initiative (BRI) has promoted massive overseas infrastructure investment and construction in BRI countries, especially railway project constructions. The railway project construction promotes some targets of Sustainable Development Goals while hurting others directly and indirectly. The direct environmental impacts of China's overseas infrastructure projects in BRI countries have been fully investigated. However, the indirect impacts of these overseas railway projects are rarely discussed. Our study quantifies indirect CO2 emissions driven by railway project construction under the BRI through the global supply chains. We find that the carbon footprint mainly relies on supply chains in BRI countries but significantly spills over to the globe as well. Upgrading BRI countries' technological levels (Hereinafter, technological levels are proxied by country-level emissions intensity) to China's average technological levels can potentially mitigate 77%-90% of emissions. China-invested overseas railway project construction (RPC) under the Belt and Road Initiative (BRI) induced 2,095.2 Mt embodied CO2 emissions during 2008-201773% of CO2 emissions induced by RPC rely on supply chains of BRI countries and 27% spills over to other regionsUpgrading BRI countries' emissions intensities to China's current level mitigates 77%-90% of carbon footprint