You want to deal in fact? Here's one: in spite of what anti-meat people will tell you, a LOT of land in agriculture is infinitely better suited to support livestock than it is to support the cultivation, growing, and harvesting of crops for human consumption -- in other words, use of that land to grow crops for human consumption is a woefully inefficient use of resources compared to what it could (and does) produce in/for livestock.
It may "seem unlikely" to you, but that doesn't make it any less true. Livestock ruminants including beef and sheep (as opposed to other livestock animals, such as pigs and chickens) create the opportunity for the amazingly efficient use of agricultural resources, and convert grass and inferior grain into a vastly larger and superior range of end products, from dairy and medicines to meat, clothing, and chemicals; claims that livestock ag is wasteful of water or an otherwise inefficient use of natural resources is pure politically-correct hooey.
A. I agree (and always have) that this is all politically correct hooey, for lots of reasons -
The notion that there are limited resources available to produce food and that food shortages are the result of resource shortages,
that forcing people in America to reduce consumption will somehow make food appear elsewhere,
that directing consumption patterns will obtain the desired results instead of some awful unintended consequence, etc.
B. The resource argument that much land is better used to raise animals, is perfectly true. There is a great deal of land available for such a purpose, much of which is massively underutilized. Land is not an issue, except perhaps in the case of a few crowded third-world countries where asset misallocation is probably the result of governments interfering with markets. There ARE cases in some countries of, for instance, potentially fine rice-land being used as pasture, merely because the local price of beef or animal feed is extremely high as a result of import restrictions, or of political/social troubles like insecure land titles.
C. On the narrow point regarding non-land resource substitution, the argument holds. Water, fertilizers, etc. are used to raise animals instead of plant foods for direct human consumption, and the US, for instance could live on a vegetarian diet with fewer resources overall used for agriculture.
The proper answer to that is - so what ? If the US uses fewer of these resources it does not mean that these are available for the use of hungry people elsewhere. Its even less feasible to ship these off to Malawi than it is to ship grain there. Its exactly the same fallacy as when our mothers told us to eat our dinners because the kids in Africa were starving. What we did with our dinners had no possible relevance to people starving in Africa. That we spend x resources on raising beef to eat does not affect starving Africans either.
As for the global climate impact - well, we all know its a bunch of hooey. The latest email releases seem dispositive on this matter.