The list you provide is missing some man made sources of CO2 and methane. It's just CO2 emissions from fuel combustion.

Meat production is almost as much as transportation, roughly 17%.

Though all meat production is not made equal; beef production is overwhelmingly more emissive per serving (6.61 lbs of CO2 per 4 oz) than pork (1.72 lbs) or poultry (1.26). Even without giving up eating meat, substituting most of your beef meals for chicken would still be a step in the right direction (and is essentially zero-cost, considering that this requires no significant lifestyle changes and anywhere that sells beef is almost certainly also going to sell chicken).

http://css.umich.edu/factsheets/carbon-footprint-factsheet

This might have ethical implications considering how much worse chicken lives are than cows lives and how many more chickens you need to kill per calorie.

Inaction will lead to climate change killing millions of humans. If someone won't consider eating vegetarian more often, switching to chicken is far better from an ethical standpoint than doing nothing.

People killed by climate change 250,000/year

Assuming switching to chicken reduces carbon by 12%, assuming carbon responsible for 250,000 death then meat consumption is responsible 30,000 ppl/year

Number of cows in u.s. 30,000,000 for 3% of global market

US market responsible for 900 deaths / year 140 chickens / cow(calorie wise)

estimated 20 years of life lost per death

18,000 QALY for 4.1 billion more chickens

Rough estimate of 2.3 minutes of human life gained per chicken raised

Thanks for doing that calculation. I really appreciate that you put in that much work.

> People killed by climate change 250,000/year

Is that a current number? Or a projection of what might happen with 2 degree or 4 degree Celsius increase in temperature?

> Meat production is almost as much as transportation, roughly 17%.

That 17% includes all transportation related to meat production. If meat was replaced by plant-based foods, not all of that transportation could be eliminated.

Livestock consume far more feed grains (mostly corn) than they produce food on their own [1]. The transportation costs to feed them are greater than the transportation costs would be if we were to feed humans on plant based foods, so transportation would actually be reduced if we lowered the amount of animal products we consume.

[1] http://news.cornell.edu/stories/1997/08/us-could-feed-800-mi...

That is a US-specific article. In the US, animal agriculture contributes about 2.8% of US total CO2eq emissions, whereas US transportation sector contributes 26%.

https://skepticalscience.com/animal-agriculture-meat-global-...

Not sure what your point is. I never said emissions related to animal agriculture outweigh total transportation emissions. What I said was reducing meat consumption would lower transportation emissions associated with food.

I wonder if corn were not subsidized to the extent it is, would alternative food sources grown on-site be more competitive, like grass?

Probably one of the problem with meat is too much water required for its processing which against has a processing cost.

The overlap is less than 2% of the total man made CO2 emissions.

Processing and transportation of animal products is 6% of the meat production emissions. Feed production also involves transportation, that would add maybe half of that (3%).

Does rice cultivation generate more greenhouse gases than meat farming?

> cannot be fixed without the entire planet committing to it.

And if the entire planet will not commit as you desire? Then what will you do? War is the ultimate extension of any policy; will you personally go kill other people because they burn oil?

I've got nothing against renewables, but don't like this kind of absolutist rhetoric.