Preliminary tests indicate that adding 100 grams of lemongrass to cow's diets helps them release roughly 33% less methane in the last three to four months of their lives.
Adding lemongrass to the diet essentially helps the cows' digestion. Without lemongrass, more methane is emitted primarily through burps, as well as farts, Restaurant Brands International chief marketing officer Fernando Machado told Business Insider.
A handful of Burger King locations in Miami, New York, Austin, Portland, and Los Angeles will begin selling Whoppers made with reduced emissions on Tuesday.
However, the chain says it hopes to inspire change across the industry. The lemongrass research and formulation is openly available, and the chain is speaking with suppliers globally about expanding the test. Burger King also released a commercial explaining the connections between cows, methane, and climate change on Tuesday.
"The beauty of it, and maybe the craziness of it, is that we are doing something ... that can make a real impact on the world by pushing the industry to adopt this new practice," Machado said.
While cattle are responsible for roughly 14.5% of global greenhouse gas emissions, cows' burps and farts are not the only way that farming contributes to climate change. Fast Company reports that fertilizer used to grow grains, fed to cows before they are sent to slaughterhouse, is a large source of emissions. Overgrazing and deforestation are also significant contributors to global warming.
Machado said that Burger King's decision to focus on lemongrass is in part simply because it is a convenient solution, even if it isn't a silver bullet that solves all of the industry's sustainability problems. Adding lemongrass to the cows' diet does not impact the cows' weight or other things that could affect how burgers taste.
"It's not really rocket science," Machado said. "Adding 100 grams of lemongrass ... can have a significant impact in terms of greenhouse emissions, which is probably the biggest negative contribution that this industry has."