Here are citations to my numbers (since I seem to be downvoted):

* Transportation: 28%

https://www.epa.gov/greenvehicles/fast-facts-transportation-...

* Livestock is 14.5% of all GHG emissions, cows are 65% of that:

http://www.fao.org/news/story/en/item/197623/icode/

* Stories on how the US Military is the world' biggest polluters:

https://www.newsweek.com/2014/07/25/us-department-defence-on...

https://www.foreignpolicyjournal.com/2009/08/15/the-worlds-w...

https://www.washingtonpost.com/opinions/america-is-the-worst...

Regarding specifically my nuclear detonation comment:

https://www.ecowatch.com/military-largest-polluter-240876060...

In addition, the U.S., which has conducted more nuclear weapons tests than all other nations combined, is also responsible for the massive amount of radiation that continues to contaminate many islands in the Pacific Ocean. The Marshall Islands, where the U.S. dropped more than sixty nuclear weapons between 1946 and 1958, are a particularly notable example. Inhabitants of the Marshall Islands and nearby Guam continue to experience an exceedingly high rate of cancer.

The American Southwest was also the site of numerous nuclear weapons tests that contaminated large swaths of land. Navajo Indian reservations have been polluted by long-abandoned uranium mines where nuclear material was obtained by U.S. military contractors.

TLDR: there's more to greenhouse gas then pollution from power plants. And nuclear power isn't problem free.

Slight correction:

https://theconversation.com/yes-eating-meat-affects-the-envi...

> All of agriculture accounted for a total of 9 percent. All of animal agriculture contributes less than half of this amount, representing 3.9 percent of total U.S. greenhouse gas emissions.

> To its credit, the FAO immediately owned up to its error. Unfortunately, the agency’s initial claim that livestock was responsible for the lion’s share of world greenhouse gas emissions had already received wide coverage.

Thanks, I didn't know of that error. I wish they'd fix the original report!

Cows just confuse the issue though since they’re mostly producing methane which although a ghg doesn’t stick around too long.

Methane is far more potent as a greenhouse gas

And the best case scenario is burning it somehow in which case it just has a CO2 byproduct

Weirdly, burning methane gives you both energy and decreases its carbon footprint by ~30x (the mole ratio is 1:1).

Methane decaying just means the atmospheric concentration doesn't increase as fast. But if you emit more than the previous year then levels will go up. And indeed, levels are currently 3 times what they were from pre-industrial levels [0].

The EPA says its Global Warming Potential over 100 years is 28-36 times CO2 [1]. 100 years sounds like a very relevant time period to me.

[0] https://en.wikipedia.org/wiki/Atmospheric_methane#Patterns_o...

[1] https://www.epa.gov/ghgemissions/understanding-global-warmin...

I hadn't heard that methane didn't last too long in the atmosphere before. What happens to it?

The UV part of sunlight breaks it down into CO2 and water. And before you get too worried about the CO2, that's from "current" carbon in the environment (the grass that the cows ate) not fossilized carbon. So it's not a net addition of carbon to the atmosphere.

The carbon is coming from the methane, though. I don't have a degree in chemistry, but the carbon from the grass doesn't end up in the atmosphere naturally, does it?