Assess and compare the effectiveness and trade-offs of three carbon dioxide removal (CDR) technologies—direct air capture (DAC), bioenergy with carbon capture and storage (BECCS), and enhanced mineral weathering—when scaled to gigatonne-level CO2 removal. Evaluate cost, energy and land/water footprint, permanence and leakage risks, lifecycle emissions, environmental co‑benefits/impacts, scalability and deployment timelines, monitoring and governance challenges, and policy implications; justify conclusions with quantitative reasoning and sensitivity to key assumptions.