Researchers in Auckland, New Zealand used a car with a special tool to study methane emissions in the city. They found that methane comes from landfills, wastewater plants, and natural gas. The study showed that some landfills and natural gas infrastructure release a lot of methane. They also discovered that gas appliances in homes can leak methane, especially in the evening. This research helps us understand where methane in cities comes from and how it affects the environment.