Consequences of diet shifts for the greenhouse gas balance of agricultural soils in Denmark

Modern food diets are often characterized as imbalanced and linked to adverse human health  outcomes. Furthermore, current food systems account for approximately one third of anthropogenic greenhouse gas (GHG) emissions. Therefore, consumers' dietary preferences  directly affect the sustainability of our environment. Various studies have assessed the impact of dietary preferences on the environment. While these studies offer valuable insights into the  complex relationship between food production and the environment, the methodologies used so far to predict the consequences for GHG emissions have important limitations, especially with respect to the consequences of diet shifts for the soil GHG balance. In this study, we employed a two-sided approach to investigate the impact of dietary changes following the EAT-Lancet diet guidelines on GHG emissions from agricultural soils. Firstly, we utilized the outputs of the economic general equilibrium model MAGNET to quantify the demand-driven changes in food  consumption at the national level for the European Union (EU) under a diet shift scenario. We then employed the DayCent biogeochemical process-based model to assess the implications for the GHG balance of agricultural soils at a regional scale, with Denmark serving as our case study. Our findings indicate that, compared to business-as-usual diets, a diet shift scenario would cause agricultural soils to experience significant carbon loss (up to 15 Mg of CO2e ha-1), a potential  increase in N2O emissions by up to 2.5%, while methane emissions from enteric fermentation show a considerable reduction of 32%. These findings underscore the challenges faced by policies aiming to create healthier food environments, which need to be aligned with efforts to reduce anthropogenic GHG emissions and protect agricultural soils.