This article explains how food choices drive land-use changes and climate outcomes in En-ROADS. Watch the video below for a summary.
The impact from the food and agricultural sector on greenhouse gas emissions and removals comes from four major sources.
Diets and agricultural practices in En-ROADS affect CO2 emissions released from deforestation, CO2 removals from forests that are left intact, N2O emissions from fertilizer use, and CH4 emissions from livestock and crops.
Plant-based diets and food waste affect the amount of emissions
En-ROADS includes options to bolster plant-based diets and reduce food waste. Both contribute to reducing the amount of crops needed, resulting in less deforestation and less greenhouse gas emissions.
The “Food from animals” and “Food waste” sliders, located in the advanced view for Agricultural Emissions, show the significant impact that food has on forests. For example, when both sliders are set to the maximum rate of reduction, like in the scenario shown in the graphs below, less food production is needed, which requires a smaller area of farmland (left graph) and the deforestation rate (right graph) declines significantly. To learn about the implications of this for climate outcomes, read the Explainer on Land and Forests in En-ROADS.
Adopting improved agricultural practices can also reduce the emissions intensity of crop and livestock production, so that less greenhouse gas is emitted per unit of food produced. The “Methane and nitrous oxide from livestock” and “Methane and nitrous oxide from crops” sliders simulate best practices that reduce these emissions.
The best graphs to see the change in the net greenhouse gas emissions, when plant-based diets are increased and food waste is reduced, are the “CO2 Net Emissions from Land Use” and “Non-CO2 Greenhouse Gas Emissions” graphs (below and in this scenario).
Feedbacks in the climate, food, and land systems
Beyond dietary choices, food waste, and agricultural practices, three other factors drive global food demand in En-ROADS: global population, GDP, and crop yield. However:
Climate change reduces crop yield and economic growth, which affects food demand and deforestation.
In the Baseline Scenario, crop yield is growing throughout the century. This trend aligns with the growth of crop yield that has occurred historically with advancements in science and technology to meet food demand. However, crop yield growth is slowed by climate impacts such as more frequent and intense droughts and floods, which can be observed in the “Crop Yield” graph (under Graphs > Land, Forestry, and Food) below and the “Decrease in Crop Yield from Temperature” figure (under Graphs > Impacts). This feedback from temperature change can be modified by the slider “Effect of temperature on crop yield” (found under Simulation > Assumptions > Agriculture).
The feedback whereby climate change reduces economic growth is covered in detail in the Economic Damage from Climate Change section of the En-ROADS Dynamics chapter in the User Guide. This feedback has a wide array of impacts, not limited to food and agriculture.
The following sections provide more detailed context.
Context and background
The expansion of agricultural land for food production is one of the major causes of deforestation. When the farmland available is insufficient to meet the crop production required, more deforestation occurs. Nearly 4900 million hectares of land are currently being used for farmland globally—this includes land for growing commercial crops and grazing land for livestock. In the Baseline Scenario, global forest area declines as food demand leads to greater farmland expansion.
Producing animal-based foods uses more land, on average, than plant-based foods, because large areas of cropland are used to produce animal feed rather than to feed humans directly. The “Food from animals” slider is the global average percent of food that comes from animal sources (such as dairy products, meat, and eggs) in 2100. En-ROADS uses the 2022 indicators of the FAOSTAT statistical database1 to determine the current value of animal-based global food consumption at around 24% of diets.
Addressing food waste can reduce the amount of farmland needed to meet global food demand. The “Food waste” slider in En-ROADS represents the global average percent of food wasted, which is currently about 30% according to the IPCC (2019).2 Food waste occurs both in the supply chains that move food from farms to consumers (e.g., when there are limitations on refrigerated storage and transport networks) and when food isn’t sold or consumers don’t use what is purchased.
Understanding the dynamics
The amount of crop production needed, whether for growing food for human consumption or for animal feed, and the productivity of the land (i.e., crop yield and grazing productivity on pastures), determines how much farmland is required to meet global food demand. When the land available for farming is insufficient to meet the crop production needed, the expansion of the farmland area comes partly from forests, which are often fertile for growing crops when cleared. Crop production and deforestation generate greenhouse gas emissions that contribute to worsening climate change impacts.
Advanced features
In addition to the graphs featured above, here are a few others that are helpful for testing the food-related features. The majority of the relevant graphs can be found in the Graphs > Land, Forestry, and Food category.
The “Crop Production Needed” graph is the best graph to see the impact that more plant-based diets and less food waste have on the total amount of food needed, which then drives the farmland area needed to produce the food, and the consequent deforestation rate.
The “Percent of Food from Animals” graph displays the percent of diets that are animal-based food. To calculate the plant-based food consumption, subtract the value on the graph from the 100% of the total diet.
Adoption of best practices in agriculture
Methane and nitrous oxide emissions are affected by both the scale of agriculture and the emissions intensity of agricultural production. Adopting best practices for livestock management (such as using feed additives to reduce enteric fermentation, or improving manure management) can reduce the amount of CH4 and N2O emitted per ton of animal product. The Agricultural Emissions main slider controls the emissions intensities of crop and livestock production, and these can be modified individually in the advanced view. Learn more in the Explainer on Methane in En-ROADS.
Methane and nitrous oxide emissions are shown by their sources under Graphs > Greenhouse Gas Emissions. Users can test how different actions in the food and agriculture sectors in En-ROADS can reduce agricultural emissions (the yellow wedge). Note that food waste is accounted for in the agriculture wedge of these graphs, rather than in the waste wedge.
1. Food and Agriculture Organization of the United Nations. (2022). FAOSTAT statistical database.↩
2. IPCC. (2019). Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems.↩