As people’s incomes rise, they tend to shift from “starchy staples” like grains, potatoes, and roots to meat and dairy products. “You’d think there would be big cultural differences between human populations in these patterns,” says Thomas Tomich, a food systems economist at the University of California, Davis, who was not involved with the new paper. “There is some, But it’s amazing how nearly universal this shift is: how rising incomes, especially moving from poor to middle class, really affects people’s consumption of livestock products.”
However, livestock and dairy are especially critical to the climate conversation because they are massive sources of methane emissions. Ivanovich’s model shows that by 2030, ruminant meat alone could be responsible for a third of the warming associated with food consumption. Dairy products would make up another 19 percent and rice another 23 percent. Together, these three groups would be responsible for three quarters of the warming of the global food system.
However, there is a silver lining: The team believes that we can avoid helping with this warming by improving our food systems and diets. That starts with eating fewer cows and other ruminants: the fewer stomachs that ferment, the better. New food technologies can certainly help, like plant-based meat imitations like the Impossible Burger or meats grown from cells grown in labs, also known as cellular agriculture. The researchers are also experimenting with feed additives for cows that reduce the methane in their burps.
In the fields, rice farmers can significantly reduce methane emissions by switching between moisturizing and drying pads, instead of leaving the plants flooded. Researchers are also developing crops that fix their own nitrogen, in an attempt to reduce nitrous oxide emissions. (Legumes do this automatically, thanks to symbiotic bacteria that live in their roots.) A team has made rice plants that grow a biofilm to act as a home for nitrogen-fixing microbes, thus reducing the need for synthetic fertilizers. The production of such fertilizers is very energy intensive, so reducing reliance on them will further reduce emissions.
But Ivanovich stresses that wealthy nations certainly can’t force methane-conscious diets on economically developing countries. In some parts of the world, a cow is simply food and milk, but for a subsistence farmer, it can be a work animal or currency. “It’s really essential that changes to diet composition are not made without making them culturally relevant and supporting local production practices and how they contribute to economic livelihoods,” he says.
Ivanovich’s 1 degree figure is an estimate, not a prophecy. For one thing, he can’t intricately model how new food and agricultural technologies could reduce emissions in the coming decades. And environmental scientist Adrian Leip, lead author of last year’s IPCC report on climate mitigation, notes that while these technologies hold promise, it’s unclear when, or how quickly, people will adopt them. “At some point, one of those technologies – I don’t know if it will be cellular agriculture or if it will be plant-based analogues – will be very cheap. It will be so tasty and nutritious that people will start thinking: Why the hell did I ever eat an animal?says Leip, who was not involved in the new paper. “I think it must happen, because I really don’t see good reasons No happen. So if social norms start to change, it can be very fast.”
To further complicate matters, there is an additional feedback loop: as the food system increases global temperatures, crops will have to endure more heat stress and increasingly ferocious droughts. “This is really a dynamic two-way interaction of change,” says Ivanovich, “where our agriculture that we produce affects our changing climate, and our changing climate really affects how well we can grow crops and support our global population. ”
But it does offer a note of hope: methane rapidly declines once people stop making it. It disappears from the atmosphere after a decade, while CO2 lasts centuries. “If we cut emissions now, we’ll experience those reductions in future warming pretty quickly,” she says.
