Lithium is a critical material for the energy transition, but its mining causes significant environmental impacts, which will intensify due to surging global demand. Here, we conduct a mining site-specific environmental impact assessment of lithium at global scale, focusing on greenhouse gas (GHG) emissions, water use, and land use. We then track the production and international trade flows of all lithium-containing commodities to assess how lithium mining impacts are distributed across global supply chains. Results indicate that environmental impact intensities of battery-grade Li2CO3 production from various mine sites differ between four times for GHG emissions to 2,885 times for land use. 56%-68% of environmental impacts generated in the original mining countries were embodied in internationally traded commodities. On the production side, China, Australia, and Chile were the top-3 countries accounting for 91%-94% of environmental impacts. Regarding final demand, China was the major consuming region, inducing 46%-47% of the environmental impacts of global lithium mining, followed by Korea (17%-18%) and the EU-27 (9%). Our findings reveal the need for spatially explicit information to accurately assess the environmental impacts of lithium mining and highlight that mitigation requires cooperation between major producer and consumer countries.