The Impact of Protein Production Systems on Greenhouse Gas Emissions

Abstract

Global demand for protein is rising due to population growth, urbanization, and changing diets. Although protein is essential for human health, its production—from livestock to plant-based and novel sources—has significant environmental impacts, especially greenhouse gas (GHG) emissions. Using the PRISMA method, scientific publications from 2013-2026 were collected, from 43 identified studies, finally 30 relevant articles were selected for analysis. Livestock, particularly cattle and other ruminants, contributes the most to methane and nitrous oxide emissions. Poultry and swine have moderate impacts, mainly from feed and manure management. Plant-based proteins generally produce lower emissions, although processing can increase energy use. Emerging sources such as insect protein, algae, and cultivated meat show strong potential for reducing emissions, with insect protein being especially efficient. Studies from Europe and Asia indicate that shifting diets toward plant-based proteins can significantly reduce GHG emissions, though effects on agricultural incomes differ. The review concludes that no single protein source is sufficient; a diversified approach—improving livestock efficiency, expanding plant-based options, and investing in novel proteins—is essential for balancing nutrition, sustainability, and economic outcomes.