Absolute environmental sustainability assessment of rice in Pakistan using a planetary boundary-based approach

The increasing anthropogenic pressure with high food demands requires fundamental changes in global food production practices while respecting the environmental and resource limits of the Earth. Half of the world population consume rice as a staple food which is grown in more than a hundred countries. This study aimed at evaluating the environmental repercussions of rice production in Pakistan following a novel approach. The adopted methodology, planetary boundary-based life cycle assessment, enabled the evaluation of the sustainable limits while respecting the carrying capacity of the Earth. The results revealed that the rice production had considerable impacts in terms of global warming (5632 ± 17.8 % kg CO2 eq), freshwater eutrophication (0.67 ± 43.5 % kg P eq), and water use (3928 ± 12.7 % m3) per tonne of milled rice; contributing to the triple planetary crisis, viz., global warming and nutrient pollution as well as unsustainable use of valuable resources. Field emissions due to microbial activity of methanogenic bacteria, fossil-based irrigation processes, and agrochemical applications were identified as the hotspots. Sensitivity analysis revealed that yield increment could be a beneficial approach to reduce environmental burdens; particularly where the impacts were surpassing the sustainable limits. Furthermore, sensitivity and uncertainty analyses also confirmed the obtained results for most of the impact categories (global warming, freshwater eutrophication, and water use) were significantly higher than the considered sustainable limits. Environmentally friendly irrigation systems, improved fertilizer use efficiency, and short-duration rice varieties with higher yield were recommended due to the substantial impacts reduction potential.