Food production could evolve from a climate catastrophe to climate champion, with a fleet of technologies that could lock away billions more tons of carbon than the industry produces, researchers on a new study say.
From sinking kelp into the deep sea, to spreading rock dust on farms, if such approaches were picked up at global scales, they would generate negative emissions on a scale that far outweighs the potential of dietary change alone.
Agriculture currently produces about a third of global anthropogenic emissions, and looking to the future, that could leap to between 50% and 80% by 2050 if the system is left unchanged, the new PLOS Climate paper says. Food system reforms are therefore deeply pressing, its researchers note, which is why they set about to interrogate what measures would achieve the deepest emissions cuts, as quickly as possible.
To do this, they developed an ambitious food system model that combined the effects of dietary change, drawing on the EAT-Lancet model, with food waste reduction, and a suite of interventions that can cut and sequester emissions linked to food. To choose interventions, they picked those for which there was peer-reviewed literature and the potential to scale up substantially this century.
This gave them a promising mix of 12 that included agroforestry, enhanced rock weathering, feed additives to reduce livestock methane, making fertilizer from renewable energy sources, sequestering carbon through kelp farming, and limiting seafloor trawling in fisheries. For each of these, the paper modeled the effects of a 25%, 50%, 75%, and 100% global adoption rate.
The question was whether a food system reformed by dietary change, reduced food waste, and agritech would not only produce enough food to feed a world population that could reach 10 billion by 2050, but with net zero emissions by that date as well.
Looking first at food, the model showed that if the whole planet agreed to a plant-focused, flexitarian diet, that would cut about 8.2 gigatons of carbon dioxide equivalent by 2050. An additional 1.1 gigatons could be locked away each year, if the abandoned farmland that was freed from livestock was rewilded.
These figures are huge, but they aren’t enough to reach net zero. This is where the agritech comes in—and where the findings get really interesting. For starters, the researchers found that technologies to cut emissions—especially making fertilizer with renewable energy sources instead of the energy-intensive Haber-Bosch process, emissions-slashing livestock amendments, and reduced trawling of the seabed—could reduce emissions by up to 6 gigatons of CO2-equivalent each year, if 100% adopted globally.
Meanwhile, the really mind-boggling numbers came from technologies designed to lock carbon away on farmland and at sea. Some of the standout options here are agroforestry, which could store over 10 gigatons of CO2-equivalent annually by foresting farmland landscapes, if adopted 100% worldwide. Farming carbon-hungry kelp and burying it in the ocean could remove an additional 11 gigatons of CO2 a year, if adopted wherever possible worldwide. Adding carbon-locking rock dust to farms every five years would lock away 5.2 gigatons of CO2 annually if all the world’s farmers embraced this technique.
If the full fleet of 12 technologies were deployed at a rate of even 50% worldwide, and even if global diets remained unchanged from today’s and there was no change in food loss or waste, they could still achieve net zero—in fact reaching net negative emissions of 13 gigatons of CO2-equivalent by 2050.
These impressive numbers are no excuse to ditch other sustainable behaviors, the researchers say. By far the greatest gains would come from combining technological interventions with dietary changes and steps to reduce food loss and waste. For example, food systems could achieve net negative emissions of 20 gigatons per year when combining 100% technology adoption with moves to halve food loss and waste. That leaps to 30 gigatons if also combined with the global spread of a flexitarian diet. In fact, “uptake of flexitarian diets increases the magnitude of net negative [greenhouse gas] emissions under all technology deployment scenarios,” the researchers write.
They paint a promising picture of what our future food systems could become—and a deeply ambitious one, which among other things will depend on huge investments to scale up expensive technologies like kelp burial. Currently the sinking process costs USD$543 per ton of sequestered carbon.
But the researchers hope the potential revealed by their impressive numbers will help to move our food systems in this direction, especially as so many of the featured technologies are already well within our grasp, and possible to implement with limited changes to supply chains and farming infrastructure—like feed additives and rock weathering.
And, with no cap on innovation, that potential will likely only grow. “We only looked at about a dozen technologies. But there are even more under development, which hold a lot of promise for the food system,” the researchers say.
Almaraz et. al. “Model-based scenarios for achieving net negative emissions in the food system.” PLOS Climate. 2023.
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