Hierarchical assessment of the environmental trade-offs in global agricultural trade

Multiple environmental impacts are embodied in agricultural trade, yet trade-offs may exist among impact categories and hinder comparisons across countries. We conduct a hierarchical assessment of the embodied environmental impacts (EEIs) in agricultural trade by first mapping four specific EEIs: greenhouse gas emissions (GHG), nutrient pollution (NP), habitat disturbance (HD), and freshwater consumption (WC), and subsequently developing two composite indices, namely cumulative EEI (CEEI) and CEEI efficiency (CEEIE), to evaluate environmental trade-offs. It was found that global agricultural trade in 2017 embodied flows of 1431.9 Mt CO2eq of GHG, 17.6 Mt of NP, 276.5 Mhaeq of HD, and 129.7 km3 of WC. Although a handful of exporters dominated across various EEI categories, the specific countries leading in each category varied, and they did not necessarily shoulder a significant CEEI burden. The composite indices identified India as the top CEEI exporter, primarily attributable to its unsustainable trade practices. However, five major exporters, namely the USA, Canada, Russia, Brazil, and Australia, contributed to global food security and hunger reduction at relatively higher CEEIE levels. Global agricultural trade mitigates local impacts of NP by 168.5%, HD by 49.6%, and WC by 83.4%, but introduces a 32.7% increase in GHG compared to the no-trade scenario. Further trade concentration risks increasing vulnerability in the global food market and may exacerbate environmental impacts. However, a 34.3% reduction in global CEEI can be achieved when the environmental intensities of agricultural production at the country level align with the global median. These findings facilitate the shaping of sustainable agriculture and trade practices. Graphical Abstract