Methane
When ruminants ferment their food, they produce methane as a byproduct. Methane remains in the atmosphere for over a decade where it traps heat and warms the planet significantly more than carbon dioxide. Current atmospheric concentrations are 160% higher than preindustrial levels, making it 2.5 times more concentrated in the atmosphere. We need to reduce the concentration of methane in the atmosphere to prevent warming the planet to over 2 degrees.
Methane is a short-lived gas, it breaks down in approximately 9–12 years to carbon dioxide which is taken up by the forage and plants that cattle eat. In contrast, carbon dioxide from fossil fuel combustion persists in the atmosphere for hundreds of years as it has no natural cycle, making it a long-lived greenhouse gas.
But while methane doesn’t stick around for centuries like carbon dioxide, it packs a powerful warming punch while it’s here. Over 100 years, methane traps 27 times more heat than carbon dioxide and over 20 years, it’s 84 times more. That’s why reducing methane still matters as it can slow the rate of planetary warming in the short-term until we can stop burning fossil fuels.
Methane emissions are our greatest opportunity to rapidly reduce warming
How cattle make methane
Cattle don’t just digest their food like we do, they ferment it first. As ruminants, cows have a specialised fermentation chamber in their digestive system called the rumen. When a cow eats grass, it doesn’t head straight to the stomach; instead, it lands in this vat, where microbes kick off a process known as enteric fermentation.
Through fermentation, these microbes break down plant-based feed to release energy. But like any good fermentation method, (think bread or beer) it also produces waste gas. In ruminants, that gas is methane, produced by a small number of microbes called methanogens. Methanogens are less than 5% of the microbes in the rumen but they use a large proportion of energy producing this waste gas. In fact, around 6–10% of the energy in a cow’s diet is lost as methane, making it a surprisingly inefficient system from the cow’s point of view.
Methane globally
Significant progress has been made with feed additives that effectively reduce methane emissions. However, because these additives must be consistently included with every mouthful of food to be highly effective, they are not a feasible solution for pasture-grazed livestock—the predominant farming method in much of the world.
Livestock farming serves as both a livelihood and a vital source of high-quality nutrients for millions of people worldwide, yet it also contributes significantly to global warming.
More than 150 countries have signed the Global Methane Pledge, committing to reducing methane emissions by 30% by 2030. Ruminant animals alone account for about 40% of the world’s methane emissions.
Delivering a solution to these challenging emissions could be game-changing, enabling sustainable livestock farming. We need a solution that benefits both farmers and the planet.
