There are 1.3 million miles of natural gas distribution pipelines in the U.S. These pipelines exist pretty much everywhere that people do, and when they leak, the escaping methane — the main ingredient in natural gas — is a potent greenhouse gas, with 84 times the short-term warming effect of carbon dioxide.1 These leaks can be time-consuming to identify and measure using existing technologies. Utilities are required by law to quickly fix any leaks that are deemed a safety threat, but thousands of others can — and often do — go on leaking for months or years.