Emissions are estimated using the formula: Emissions (kg CO2e) = Weight (kg) / 1000 × Distance (km) × Emission Factor (g CO2e/tonne-km) / 1000. Emission factors are well-to-wheel (WTW) values from the GLEC Framework v3 (2023) and EcoTransIT (2024): Sea (Container) = 8 g/tonne-km, Air (Freighter) = 2000 g/tonne-km, Air (Passenger) = 1000 g/tonne-km, Road (HGV Truck) = 115 g/tonne-km. Assumptions include ~70% load for air and sea, ~60% for road with 20% empty running, and radiative forcing for air. Results are estimates; for compliance (e.g., ISO 14083), use carrier-specific data or tools like EcoTransIT.org.