An international team of researchers found that global emissions of methanea powerful greenhouse gas, rose faster than ever in the three years ending in 2022. new report of the Global Carbon Project, dozens of scientists reviewed many different emitters of methane and found that two-thirds of methane emissions came from human activities in 2020, while the rest came from natural sources such as wetlands.
The way we eat, and the way we dispose of food, play a major role in humanity’s growing methane problem. The report zooms in on roughly two decades of data: one from 2000 to 2009, and another from 2010 to 2019. (It also includes analysis of emissions in 2020 and beyond where data was available.) The authors found that agriculture and waste — including landfills and wastewater management — was responsible for releasing nearly double the methane emissions into the atmosphere than fossil fuel production and use from 2010 to 2019.
The trend is hardly surprising to experts who track global greenhouse gas emissions. This is the Global Carbon Project’s fourth report tracking the sources and sinks of methane emissions, and in the last global methane budget, published in 2020, agriculture and waste also contributed about twice as much methane emissions as the methane released during extraction. the air leaked out. of oil, gas and coal. But the findings come at a time when more than 155 countries have committed to it to reduce their methane emissions by 30 percent by 2030, indicating that the amount of work left to do to meet this climate goal has grown. This is both a problem and a potential opportunity, said one report author.
The numbers detailed in the report, particularly from the agricultural sector, are not “hard numbers,” said Peter Raymond, a professor of ecosystem ecology at the Yale School of the Environment and one of dozens of scientists contributing to the methane budget report. contributed. .
Agricultural production uses up just under half of the planet’s habitable landwhich represents a lot of room for intervention. Animal agriculture is a particularly large contributor to global methane emissions: The largest source of methane emissions within the agricultural sector is livestock. Ruminants such as cattle and sheep release methane into the atmosphere when they farm. This source of methane is technically known as enteric fermentation.
Reducing meat consumption – especially red meat, especially in high-income countries – represents an opportunity to lower methane emissions. “There is a place to change our diet,” said Richard Waite, director of agricultural initiatives at the World Resources Institute.
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For regions that “consume more meat than the global average,” Waite said, “shifting from meat especially to plant-based foods” presents a real opportunity to reduce methane emissions.
Raymond noted that other climate solutions are emerging that target enteric fermentation; it includes animal feed additives such as seaweedwhich can reduce cattle’s methane production.
The other two major sources of methane from agriculture are manure management and rice production. In those areas, there are also a number of possible solutions that would reduce methane emissions, such as separating animal waste through liquids and solids and finding alternatives to flooding rice paddies.
Raymond pointed out that governments are particularly interested in solutions to reduce methane emissions because “it is also seen as a possible way to buy time” while governments and the private sector tackle the monumental task of replacing fossil fuels with renewable energy. CO2 represents more than 99 percent of the greenhouse gases in the atmosphere by concentration, and it is responsible for 64 percent of the heat trapped in the atmosphere. That, he said, makes carbon “a much bigger nut to crack.”
Methane spends much less time in the atmosphere than carbon dioxide; about 20 years after it is released, most of it will have decayed, while carbon dioxide remains in the atmosphere for hundreds of years. But methane also generates heat much more easily than carbon dioxide — about 80 times more in its first 20 years in the atmosphere — meaning it contributes significantly to global warming in the short term. This is good news – sort of – because by the same token, any reduction in methane emissions will immediately have more of an impact on the climate.
The fact that researchers have found that a majority of methane emissions stem from human activity is “a blessing and a curse,” said James Gerber, a senior scientist focused on agriculture and land use at Project Drawdown, a climate solutions -nonprofit organization. “It’s sobering that so much of it is people’s fault,” he said. But “we can actually do something about it if we’re a big part of the problem.”
The differences between the agricultural and the energy sectors really illustrate the challenges of decarbonizing food systems. The largest source of man-made greenhouse gas emissions is the energy sectorand within that, the burning of fossil fuels such as oil, gas and coal to create electricity. Therefore the path is to decarbonisation is obvious: Move away from fossil fuels to renewable energy.
For consumers, that transition will happen almost in the background; once the necessary changes are made to power grids, “you flip a switch, and the adoption is automatic,” says Mario Herrero, a professor at Cornell University’s school of agricultural sciences. With agriculture, decarbonization will likely require the adoption of technological solutions by farmers, as well as dietary shifts by consumers. These kinds of behavioral changes are tricky; Herrero points out that policy incentives may be needed to get farmers on board with new practices. “The adoption of new technologies in the livestock sector has been about 20 percent over 15 years,” Herrero said. “So it takes forever.”
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Still, when it comes to food, change is possible, Waite said. “Food is something we can all talk about,” he said. “We are all familiar with it. We all make our own decisions about it three times a day or more.” System-level change is needed to make a difference on a global scale — but it can start at the consumer level, Waite said.
Our food systems also play an important role in potentially reducing emissions from landfills. The Methane Budget report found that waste accounted for nearly a fifth of global methane emissions in 2020. And while not all of it comes from food waste, a good portion of it does. For example, in the US, 58 percent of landfill methane emissions come from food wasteaccording to the EPA.
The role that waste systems play in methane emissions is getting more attention, says Emily Broad Leib, who heads the Food Law and Policy Clinic at Harvard Law School. “I think there’s a growing awareness that this is something we need to address if we really want to make an impact on methane emissions,” she said.
Certain countries have made significant progress in diverting food waste to compost, such as South Korea, which basically eliminated food waste by making organic waste in landfills illegal. In France, a ban on throwing out unsold food at grocery stores led to a decrease in waste. But agriculture and waste – which somehow represent the beginning and end of our food systems – are still major emitters of methane in the Global South, according to the Methane Budget report.
The imperative is therefore to scale and translate solutions to work in even more environments. “There’s a familiar playbook emerging around the policy tools that can get food out of landfills,” Broad Leib said. “And we need to roll it out faster.”
