Environmental-social-economic synergy of China's investment on BRI countries

China's substantial capital investments in the Belt and Road Initiative (BRI) countries spur significant economic growth but also lead to environmental pressures. Capital assets, vital as production intermediates, are treated as consumer goods in traditional accounting, overlooking their productive attributes. To bridge the gap, this study uses the flow matrix method to endogenize Chinese investment capital into a global input-output model. We found that China's investments in 120 BRI countries resulted in a 55 Mt carbon footprint, 2.8 % of these nations' global investment carbon footprint, while generating $78.16 billion in economic benefits and supporting 7.2 million jobs. Moreover, these investments significantly boosted local employment, with Chinese investment labor intensity (labor per emission unit) exceeding the global average. If China applied its domestic technical standards to overseas investments, the investment carbon footprint in these countries could drop by 15.4 % to 47.1 Mt, and value-added and labor intensity could increase by 16.7 %.