They found combining a dietary shift, emissions pricing, and international income transfers could make the world’s food system emissions-neutral by the end of the 21st century - providing at the same time a healthier nutrition for a growing world population.
“Just shrinking the size of our current food system won’t cut emissions much. Instead, we need to transform the very nature of that global food system,” said Benjamin Bodirsky, researcher at PIK and the World Vegetable Center in Tainan, Taiwan and author of the study.
“That means on the one hand people consume what they need in terms of nutritional requirements, curb food waste and eat a more balanced diet, with much more vegetables and fewer animal products. On the other hand, a qualitative transformation means more efficiency, hence producing food in a less-polluting way: smarter dosing of fertilisers or planting higher-yield crops,” he added.
“Also, carbon pricing could help steer farmers towards lower-emission agricultural practices, because emitting less means paying less. Put together, this could drastically reduce greenhouse gas emissions,” Benjamin Bodirsky said further.
The way we produce food and manage our land is responsible for up to a third of global greenhouse gas emissions along the entire supply chain.
“So we looked at what this system would look like in a hypothetical degrowth world: On the basis of a review of degrowth proposals, we created a set of scenarios to feed into a food and land systems computer simulation to explore their effect on the food system,” David Chen, researcher at the Potsdam Institute for Climate Impact Research and author of the study, explained.
“We took a step back from the heated normative debates about degrowth. What we found is that the current food system is basically unsustainable for any society, regardless of economic growth rates,” David Chen stated.
The simulations show that simply curbing growth in rich countries would not yield sizable sustainability benefits in the food system. Financial transfers from higher to lower income countries within the current development paradigm may even increase emissions. That is because carbon-intensive diet changes towards animal products and processed foods are most pronounced when countries move from low to medium incomes.
A sustainable diet benefits planet and people
Yet when the scientists included consumption changes and efficiency gains incentivised by a price on carbon, the results showed an improved nutritional outcome for all consumers, lower greenhouse gas emissions, and in consequence also less economic activity in agriculture required for food production.
“For the food sector, we can say that a certain degree of degrowth would be the result of the sustainable transformation, not the starting point. So basically this is not really about less but about different growth,” said Hermann Lotze-Campen, co-author from the Potsdam Institute.
Importantly, a sustainable food system transformation that takes into account all costs for the environment would entail a slight increase in food prices, felt especially by the poor, the scientists show.
Any transformation hence must be accompanied by a well thought out policy mix of smart taxing schemes, social compensation for CO2 pricing, and international transfers. Also, making agriculture more climate-friendly, in example by controlling nitrogen flows in croplands, requires investment. These costs, however, are likely offset by the restoration of ecosystem services.