Low-methane food can speed up planetary recovery
We’ve entered a decade-long race to prevent global temperatures from rising 1.5°C above pre-industrial levels. Rapidly halving our greenhouse gas (GHG) emissions is essential to our success. That’s where methane comes in. Reducing emissions of this short-lived but powerful super-heater could buy us enough time to avoid irreversible tipping points. The food system needs to cut emissions from livestock burps and rotting rice, but it’s currently lagging. How can it catch up?
Just like the glasshouse in your garden allowing vegetables to grow all year round, some of the gases we emit to maintain our modern lifestyles trap solar heat, leading to the greenhouse effect. Unfortunately, our ecosystems are ill-suited for the GHG-fueled hothouse we’re heading towards.
Carbon dioxide – the key driver of global warming – is most abundant in the atmosphere, where it lingers for centuries. But despite their lesser presence and comparatively short lifespan, other GHGs – nitrous oxide and methane notably – boast far greater capacity to radiate heat back into the atmosphere. As much as 84 times more in the case of methane. The gas, emitted mainly through human activity, has managed to contribute 30% of the overall warming of our planet though it only lives around a decade and impacts our climate for another. This illustrates how vital it is to cut our methane emissions. Fast.
This super-heater and its cataclysmic impact on climate have long been veiled by the systematic conversion of all GHG emissions to “CO2 equivalents”. Considering the tight ten-year deadline we are working with, it’s vital to redirect our attention to the gases that most deserve immediate action. The UN estimates that cutting methane releases by 45% will enable us to avoid around 0.3°C of warming by the 2040s. In its sixth assessment report published just today, the Intergovernmental Panel on Climate Change also stresses the urgency of cutting its emissions. “Methane reductions are probably the only way of staving off temperature rises of 1.5C,” says lead reviewer Durwood Zaelke.
Since on-farm discharges represent about 50% of all anthropogenic methane emissions and given its short-lived nature, detoxing the entire food system – or parts of it – from the potent gas today is likely to start having significant cooling effects already in the 2030s. That will require dramatic changes in agricultural practices, livestock management, as well as eating habits.
Setting the pace for planetary recovery with methane reduction
Atmospheric methane concentrations have gone up by 150% over the last two centuries, breaking records year after year. The Global Carbon Project attributes recent rises to agriculture and waste management. Other significant sources include leaks from oil and gas extraction as well as naturally occurring “background” methane from fissures in the Earth’s surface, volcanoes, wetlands, and decomposing organic matter in nature. And concentrations may soar even further as methane releases from thawing permafrost accelerate.
The good news is: we already have the tools to cut all human-generated emissions by 45% this decade, according to the UN’s 2021 Global Methane Assessment. The fossil fuel industry – responsible for about a third of anthropogenic emissions – would benefit the most from these existing technologies. The food system, however, will need to do the heavy lifting. Behavioral changes from producers to consumers should go hand in hand with emerging technologies in cattle raising and rice farming, the two major agricultural culprits, to maximize long- and short-term impact.
Cattle: Tweaking the diet of methane’s poster child
All ruminants, including sheep, goats, and deer, burp out methane when digesting grass fibers. Together, they account for a third of agricultural emissions, but none is as vilified as cows. Certainly because, in addition to releasing more of the potent gas per kg of protein, the extensive consumption of its meat and milk drives deforestation (to make room for grazing grasslands), runs water reserves dry, and increases risks of cardiovascular diseases.
Consuming considerably less ruminant meat is undoubtedly the ideal way forward and, it’s gaining momentum. A survey conducted by IPSOS in 2018 found that flexitarians represent 14% of the world population. Vegetarians account for 5% and vegans 3%. These shares have likely increased in light of the soaring number of those who tried veganism this January and the popularity of Meatless Mondays. But behavioral change can be a slow process. The Food system needs to introduce alternative low-methane diets to allow all population segments to join the race.
Recognizing the urgency to support methane-reducing efforts, the Food Planet Prize rewarded not one but two initiatives tackling our protein craze in its inaugural year. Prizewinners icipe and Future Feed respectively tap into the power of nutritious insects for human and livestock consumption, and methane-blocking seaweed as a feed supplement for cows.
Beyond seaweed, more and more researchers are investigating other methane-reducing feed supplements. In this category, one finds tannins, oils, grains, seeds, as well as garlic. All attack the problem at its source: they prevent bacteria in the cow’s first stomach from turning grass into methane.
But each solution comes with its own set of challenges. Corn production, for example, requires large fields, causing soils to release CO2 instead. Flaxseed increases the percentage of undigested fibers in manure, another source of methane. Mitigation through unprocessed cottonseed, which also improves dairy cows’ milk production, is offset by high nitrogen emissions.
That's why some scientists intend to avoid these trade-offs by repurposing methane found in stables as an energy source or by breeding climate-friendly cows. Others envisage vaccines that create antibodies against methane-producing microbes found in cattle guts or probiotics to facilitate their digestion. Startup Zelp instead develops a mask-like device that converts methane to CO2 directly from the cow's breath.
Most of these innovations are still in their infancy. Their preliminary efficiency varies from 20% for seed oils to 50% for probiotics and a striking 80% for seaweed. If successful and widespread, these tweaks may allow cattle to retire from its unfortunate methane poster child image and restore its environmental reputation. After all, cows fertilize our grasslands and keep them healthy. Though technology is bypassing animals altogether with beef cultured from cows’ muscle tissues. Several startups are indeed extracting stem cells from actual cows to grow meat in vitro, in labs.
Rice: Purging water from the production of our beloved grain
To savor delicious sushi, jollof, or risotto, we need rice – a lot of it. In fact, one-fifth of our calory intake comes from rice which is a staple food on all continents. As much as farming rice is a matter of food security, it’s also a highly polluting activity contributing 11% of anthropogenic methane. This is due to the grain’s semiaquatic nature. It thrives under submerged conditions, but flooding rice paddies prevents oxygen from penetrating the soil. Waterlogged soils being conducive for the decomposition of organic matter, the practice results in the perfect breeding ground for methane-producing bacteria.
While diversifying our diet is the ideal long-term solution, the food system must also commit to producing rice with a low-methane footprint. Producers around the world are already balancing between too little (lower yields) and too much water (higher methane). Some tackle the quantity; others focus on the frequency of watering.
Rice farmers in China, for example, have reduced their methane emissions by 70% since the 2000s, thanks to single mid-season drainage. Instead, in India, intermittent irrigation is the water management practice of choice. Both methods help roots feed oxygen to the soil and thereby reduce methane production. They further showcase the same advantages, namely increased yields and decreased water usage. They also display the same drawback, i.e., higher nitrous oxide concentrations, a greenhouse gas even more potent than methane. Scientists, however, estimate the Net GHG emissions to be positive.
Unfortunately, these are not one-size-fits-all solutions. Case studies by the World Resources Institute found that these water-reducing techniques translated to zero yield gain in the United States. This stagnant productivity constitutes an obstacle to their adoption. Lack of control of irrigation and drainage systems is yet another hurdle. Moreover, accelerating water scarcity makes irrigation increasingly unrealistic.
Some farmers are therefore turning to ground cover rice production systems, aka covering paddies with plastic films to retain soil moisture. The catch? The practice, also known as mulching, pollutes soils with microplastics as films break down. Biodegradable mulches may hold the solution and allow rice farmers to increase their yields while lowing their methane output.
Limiting water inputs is actually a two-in-one solution since an average of 3000–5000 liters of water is needed to produce one kilo of rice. This is twice or more than what is used for other grains. But nature-based solutions are not always about reducing irrigation. Some consist of removing straws and weeds from flooded paddies and therefore avoiding their decomposition.
On the high-tech end, and similarly to cattle raising, scientists are exploring new breeds and additives as mitigation strategies. A Danish team proved that adding cable bacteria to (potted) paddy soils led to an impressive 90% decline in methane. The mechanism is simple: these microbes compete for the same resources (CO2 and hydrogen) as those who emit methane, and since they are more efficient, methanogens starve to death.
Beyond agriculture: Mitigating spillovers from the food system
While most of the food system’s methane emissions stem from rice and beef production, other agricultural activities contribute too. One example is fertilizers used to dope agricultural productivity running off into water ecosystems. Here, they cause a phenomenon known as eutrophication. The excess nutrients – primarily nitrogen and phosphorous – wash from fields and pastures to lakes, rivers, and wetlands. This leads to algal blooms and boosts the growth of other organic matters, both of which release methane when decomposing.
Similarly, coastal aquaculture’s methane emissions are higher than untouched coastal habitats such as mangrove forests and salt marshes. Agricultural waste, often burned or dumped in landfills, is another critical food system source of methane. And here too, solutions exist. Companies like Kriya Labs transform post-harvest residues destined to be burned into biodegradable packaging. Another example is the Sustainable Rice Platform which helps farmers minimize losses with improved harvesting techniques, storage technologies, and alternative markets for rice that would otherwise be discarded.
Case in point, an estimated one-third of all food produced is wasted, contributing to 6-8% of all human-induced GHG emissions. Rotting food emits huge amounts of methane. Reducing food waste across the supply chain is therefore crucial. Again, meat is of particular concern: its carbon footprint – mostly derived from the super-heater – contributes to more than 20% of the total food waste footprint while less than 5% of it is wasted. Cereals and vegetables are the most wasted.
No climate mitigation without limiting food-related methane
Natural systems have always released greenhouse gases, but human activity is emitting them at unsustainable speed and unlivable levels. For our survival, we must stay within 1.5°C limits before, very soon, reverting to pre-industrial levels. But at 1.2°C excess, summer 2021 already feels apocalyptic.
The race against the clock was punctuated by ravaging floods, drought, heatwaves, and wildfires. The frequency and intensity of these extreme weather events seem even to have exceeded experts’ worst-case scenarios. And the harder and more often they hit, the more methane we release. Scientists are already studying how to produce rice in a hotter climate while limiting methane emissions. Rice straw-derived biochar seems promising. But let’s not put the cart before the horse. Let’s not test our resilience before practicing our adaptability.
Yes, humans are creatures of habits, and behavioral change can take time, but we can change course in the face of imminent danger. The ozone hole success story is a testimony to our ability to adapt. And this is as imminent as it gets. Reducing methane offers a chance to keep the planet bearable until it is livable again. It will buy us time and help us stay in the race.
Solutions are not perfect, but we should not let perfect get in the way of good. So, whether with seaweed-fed beef or a new breed, rainfed or low-water rice, organic or rescued food, all or none of the above, the food system needs to leverage social, scientific, and technological advancements to cut its methane emissions. And it must do it now.