Cars and factories create lots of greenhouse gas. Cows, deer and goats also create gasses. A lot of the world's methane comes from farm animals. Methane is the second most common greenhouse gas. Billionaire Bill Gates wants to cut methane from farm animals. He put money into a technology start-up called Rumin8. It has created a seaweed-based supplement. It says this will reduce the methane in animals' burps.

Bill Gates started Microsoft. He puts a lot of money into environmental projects. He thinks farming animals less will help climate change. A third of all greenhouse gas emissions is from farming animals. Mr Gates' spokesperson said: "Rumin8 offers a low-cost toolbox that [is] effective in reducing emissions." He added that his team would work closely with Rumin8. They will help farmers all over the world.