I'd urge anyone interested in this debate to read the following book
https://www.amazon.co.uk/Meat-Benig...856230554/ref=cm_cr_arp_d_product_top?ie=UTF8
it's quite a long an involved read but you don't have to read it from cover to cover, you can use it as a reference book to look at some for the specific issues the author (Simon fairlie) deals with such as climate change.
Here's a brief interview with the author that outlines his argument
http://content.time.com/time/health/article/0,8599,2024133,00.html
As you will see, he isn't arguing in support of the status quo. I tend to agree with him that there are problems with our current model of food production, as farmers we don't really produce food anymore, we produce agricultural commodities which are sometimes processed into food, often they are made into other things like bio fuel or animal feed.
what we need to do is change our model of food production to one that primarily produces food for humans, the most sustainable version of such a system would be one that included animals as part of the rotation. this week's costing the earth programme on radio 4 asked the question: what would a livestock free countryside look like, and one of the places they visited was an organic farm that grew veg on a stockless system. Obviously, the big draw back with such a system is that it's virtually impossible to replace fertility from harvested crops without animal manure. this farm claimed to do so by importing green waste and wood chip to make compost and having a two year green manure phase in a four year rotation. So they were growing crops for two years and the other two years they plant grass and legumes to mulch back into the ground and build fertility back up for the next cash crop. presumably the were using tractors and mowers to do this, when the more obvious answer would be to get some ruminants to eat it and convert it into fertiliser and meat for free.
Fairlie's argument is that animals used in this way within a 'food orientated' rotation produce protein without any environmental cost. The alternative where there are no stock, means that we would be wasting a usable resource that could be used to produce free protein, and instead would be importing our protein from far off countries where people go hungry.
Meat is an easy target here, the obvious answer if we were serious about climate change would be to leave the carbon in the ground. that would mean radical changes for everyone's lifestyle though, where as farming is a soft target, methane is a potent but short lived greenhouse gas and hence can be seen as a 'quick fix'. we tend to talk about climate change in terms of CO2 emissions but methane is different, and a lot depends on the arbitrary figure that we attribute to methane as a co2 equivalent. I also believe that some of the higher figures for CO2 attributed to meat production include the burning of the rain forests, which seems a little harsh when applied to welsh hill lamb for instance, and in some cases even the CO2 that the cows exhale as part of the carbon cycle. so whilst emissions from meat production are an issue, there is an element of the deck being stacked against us.
Why? well people stand to make money i guess, there's money to be made from selling highly processed 'plant based' foods, vegan pizzas, ready meals and expensive processed ersatz meat alternatives will be big money earners, and if people can buy their vegan ready meal in its black plastic tray with cling film cover and cardboard sleeve, they can carry on consuming all the other cheap tat that makes up the modern world safe in the knowledge that they're saving the planet.
There is no quick fix to climate change, if we want to stop it then we need to radically alter our lifestyles, which means consuming less, travelling less, having less stuff, living simpler lives and re connecting with how our food is produced and being prepared to pay a bit more to have it produced properly. The chances are that this isn't going to happen because it's just too hard, so vegan ready meals it is then.