Higher GWPs for methane and other gases found in the IPCC Fifth Assessment Report are not yet incorporated into the Inventory.
![](https://pbs.twimg.com/media/DfL1kb-X0AQcbU9.jpg)
Enteric fermentation (cow burps and farts) is the number one source of methane in the US.
![](https://pbs.twimg.com/media/DfL2eWgXkAAfv2_.jpg)
![](https://pbs.twimg.com/media/DfL4DEmW0AA1pWl.jpg)
![](https://pbs.twimg.com/media/DfL49ZwW4AEKval.jpg)
This drop occurred as gas utilities added 739,000 miles of distribution pipeline to serve 19 million more customers with gas service.
![](https://pbs.twimg.com/media/DfL9CncXUAIEeGe.jpg)
![](https://pbs.twimg.com/media/DfMBVe6W0AAbu3R.jpg)
EPA's Inventory is a continual work in progress. Trends in natural gas system emissions are markers that signify directionally how new information better informs our understanding of GHGs from natural gas.