Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice

TLDR

Agriculture feeds over 7 billion people but is a leading cause of environmental degradation. The study aims to understand how alternative production systems, input efficiency, and food choice drive environmental degradation to reduce agriculture’s impacts. Per unit of food, the meta‑analysis of 742 life‑cycle assessments shows that organic systems use more land and cause more eutrophication but emit similar GHGs as conventional systems, grass‑fed beef uses more land with similar GHGs, low‑input aquaculture and non‑trawling fisheries have markedly lower GHGs, increasing input efficiency benefits both crops and livestock, and plant‑based foods have the lowest environmental impacts, with ruminant meat about 100 times higher, indicating that dietary shifts toward low‑impact foods and higher input efficiency yield greater benefits than switching to organic or grass‑fed systems.

Abstract

Global agricultural feeds over 7 billion people, but is also a leading cause of environmental degradation. Understanding how alternative agricultural production systems, agricultural input efficiency, and food choice drive environmental degradation is necessary for reducing agriculture's environmental impacts. A meta-analysis of life cycle assessments that includes 742 agricultural systems and over 90 unique foods produced primarily in high-input systems shows that, per unit of food, organic systems require more land, cause more eutrophication, use less energy, but emit similar greenhouse gas emissions (GHGs) as conventional systems; that grass-fed beef requires more land and emits similar GHG emissions as grain-feed beef; and that low-input aquaculture and non-trawling fisheries have much lower GHG emissions than trawling fisheries. In addition, our analyses show that increasing agricultural input efficiency (the amount of food produced per input of fertilizer or feed) would have environmental benefits for both crop and livestock systems. Further, for all environmental indicators and nutritional units examined, plant-based foods have the lowest environmental impacts; eggs, dairy, pork, poultry, non-trawling fisheries, and non-recirculating aquaculture have intermediate impacts; and ruminant meat has impacts ∼100 times those of plant-based foods. Our analyses show that dietary shifts towards low-impact foods and increases in agricultural input use efficiency would offer larger environmental benefits than would switches from conventional agricultural systems to alternatives such as organic agriculture or grass-fed beef.