気候変動：世界の食料システムに由来する温室効果ガス排出だけで2100年の気温が約1℃上昇するかもしれない

Emissions resulting from the global food system could add nearly 1 °C of warming to the Earth’s climate by 2100, a modelling study published in Nature Climate Change suggests. The findings also indicate that improvements to production and consumption practices could avoid 55% of this projected warming.

Global food production is a considerable source of greenhouse gas emissions, particularly methane, nitrous oxide and carbon dioxide. Previous attempts to model these interactions have failed to account for continuous and evolving emission levels and require an arbitrary timespan to weigh the importance of different gases, commonly 100 years, which skews the climate impacts of either short- or long-lived greenhouse gases.

Catherine Ivanovich and colleagues use current global food production and consumption patterns to project future warming impacts throughout the twenty-first century under five population scenarios. They developed a detailed inventory of current greenhouse gas emissions for 94 different food items based on an extensive literature review. They found that the food systems alone could contribute nearly 1 °C to climate warming by the end of the century. Methane accounts for nearly 60% of warming associated with the food system, and carbon dioxide and nitrous oxide account for around 20% each. The authors also found that improving the production practices of foods associated with the highest relative contribution (ruminant and non-ruminant meat, dairy and rice) could avoid nearly a quarter of the predicted warming by 2100.

Ivanovich and colleagues argue that adoption of a medically recommended diet across the globe—which would entail reducing dietary protein content in some geographies and increasing it in others—combined with energy decarbonization and a coordinated effort to reduce food waste, could lead to another quarter of a degree of avoided warming by the end of the century.