According to the EPA, as of 2015 agriculture is responsible for 9% of American GHG emissions and transportation is 27%.

https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...

Maybe you're thinking of the global level, where agriculture is comparable to transportation and the IPCC grouping "agriculture, forestry, and other land use" (AFOLU) is greater:

https://www.ipcc.ch/pdf/assessment-report/ar5/wg3/ipcc_wg3_a...

I would venture that the reason that latter figure doesn't come up much in American policy discussions is because American policies can do a lot more about American transportation emissions than American policies can do about foreign agriculture or deforestation.

The US also imports quite a bit of food (I'm not finding a definitive figure right now, but seeing 15% in several places), so that complicates the calculation a bit. Also, you'd want to see a breakdown of how much transportation comes from agricultural activities as well, to get a better idea of the full picture.

Still, agriculture is a big player no matter how you cut it, and your own eating habits are a lot easier to control than overall policy or law changes (and probably even your transportation, given the strong need for cars).

The US is a net exporter of food.

For a US consumer making choices and understanding the impact of what they eat that doesn't matter, what matters is what ends up on the plate. A ton of exports ends up as feed for animals, which can then be re-imported as well.

Yea, I was thinking of the global level. Focusing on US policy is a fair point. There are definitely things the US can do to address deforestation internationally, but maybe it's a more difficult task than focusing on domestic transportation.

Also, where does the Department of Defense fit in this diagram? Are they lumped in with other energy users, or are they left out entirely?