Highlights:

The world's food system network generates between 21% and 37% of the planet's greenhouse gas emissions each year. With the global population approaching 10 billion by mid-century, greenhouse gas emissions of the global food system—if left unchecked—could grow to 50% and 80% by 2050.

The study uses a global food system model to explore the influence of consumer choice, climate-smart agro-industrial technologies, and food waste reductions for achieving net negative emissions (i.e., where GHG sinks exceed sources sector wide) for the year 2050.

The results reveal a high-end capacity of 33 gigatonnes of net negative emissions per annum via complete food system transformation, which assumes full global deployment of behavioral-, management- and technology-based interventions.

The most promising technologies for achieving net negative emissions include hydrogen-powered fertilizer production, livestock feeds, organic and inorganic soil amendments, agroforestry, and sustainable seafood harvesting practices. On the consumer side, adopting flexitarian diets cannot achieve full decarbonization of the food system but has the potential to increase the magnitude of net negative emissions when combined with technology scale-up.

Previous research suggests that such GHG emissions can be reduced by ~50–70% via worldwide adoption of diets with smaller contributions of animal sourced foods than average diets, such as a Mediterranean, pescatarian, or vegetarian diet. Our model suggests a similar magnitude of global GHG emissions abatement via the adoption of a flexitarian diet, which is higher in fruits, vegetables, legumes, whole grains, and nuts, and lower in red meat, eggs, and starchy vegetables (potatoes) than the current average global diet.

Examples of technologies:

In a process called "enhanced weathering," for example, silicate rock dust can be added to crop soils every five years to accelerate the formation of carbonates. This process devours carbon dioxide, which can sequester several billion metric tons of carbon per year, according to the paper.

Through agroforestry, planting trees on unused farmland can impound up to 10.3 billion metric tons of carbon annually, while seaweed can be farmed at the ocean surface and then buried in the deep sea, removing up to 10.7 billion metric tons of carbon dioxide.

Supplementing livestock feed with additives could reduce methane emissions by 1.7 billion metric tons and applying biochar to croplands may reduce nitrous oxide emissions by 2.3 billion metric tons.