Twenty percent of annual greenhouse-gas emissions come from agriculture—and methane emitted by cattle and dairy is the primary contributor (7.9 gigatons of CO2e, based on 20-year global-warming potential). Research has established that **low-methane feed additives** could effectively stop up to 90 percent of methane emissions. Yet applying those additives for free-range livestock is particularly difficult. An alternative solution is an **antimethane vaccine that produces methanogen-targeting antibodies.** This method has had some success in lab conditions, but in a cow’s gut—churning with gastric juices and food—the antibodies struggle to latch on to the right microbes. Quantum computing could accelerate the research to find the right antibodies by precise molecule simulation instead of a costly and long trial-and-error method.