Cow flatulence and its methane is often blamed for being worse for global warming than carbon emissions.
But is it really cow farts that are the problem?
NBC's Left Field team, armed with methane sensors, found it was mainly cow burps that were responsible for producing the gas.
The beef and dairy industry in California generates 50% of the state's output of methane. The state, which has 2.5 million dairy and beef cattle, is now requiring the industry to reduce its greenhouse gas emissions.
Research shows that the answer to the methane problem might lie at the bottom of the ocean.
Scientists from California and Australia have found feeding seaweed to cows could drastically mitigate methane emissions from their burps.
In the past citrus, nutmeg and oregano have been added to cows' diets in a bid to reduce methane emissions.
However, for seaweed production to measure up to the demand, science needs to evolve in a way that it can be grown outside of laboratory settings in tanks, and potentially even in the open ocean.
Find out more in the video player, above.