Lithium is a critical material for the energy transition, but its mining causes significant environmental impacts that will intensify due to surging global demand. Here, we conduct a mining site-specific environmental impact assessment of lithium on a 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 4 times for GHG emissions to 2885 times for land use. 56-68% of environmental impacts generated in the mining countries were embodied in internationally traded lithium flows. 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.