Neither Garnett nor Smil is talking about “an 1850’s agrarian agriculture” or going back in time or killing off half the world’s population, and, trust me, they know FAR more about these issues than you do (or ever will). Your comment is just a pastiche of knee-jerk anti-livestock, vegan talking points that you accept as true because they allow you to placidly assume that you’ve made “the best choice.” .
As far as “disagree[ing] with the UN” is concerned, you should be aware that the Guardian article you linked to was quite inaccurate in a number a respects (surprise, surprise! When was the last time a journalist got things 100% right?). First, the report it referred to was not, as you and the author of the news story seem to think, a position held by or promulgated by the UN. It was a report by a particular “working group” to a sub-organization within UN (the International Panel for Sustainable Resource Management of the UN Environment Programme), and like all such reports, it includes a disclaimer saying that the views expressed do not necessarily represent the decision or the stated policy of the United Nations Environment Programme” (much less the policy of the entire UN!)
Second, the report itself did NOT actually say, as the new article claims, that a “global shift towards a vegan diet is vital to save the world from hunger, fuel poverty and the worst impacts of climate change.” The report, which dealt with a broad range of resource-use issues and was NOT focused on livestock or the impact of animal foods, only briefly dealt with livestock in a discussion of the impacts of food production in general, saying “Unlike fossil fuels, it is difficult to look for alternatives: people have to eat. A substantial reduction of impacts would only be possible with a substantial worldwide diet change, away from animal products.” At most, this refers to a reduction in the consumption of animal products, not their complete elimination, and as I said, this is NOT, in any event, the “policy” or a “position” of “the UN” It’s just something the authors of the report said.
Believing that promoting veganism this is the “UN position” requires one to ignore all the PRO-livestock publications coming out of the UN, particularly the Food and Agriculture Organization, which publishes FAR more comprehensive and specialized reports on, well, food and agriculture, which generally recognize the positive contribution of livestock to true sustainability and food security — reports like this one on meat and milk from grass-based systems http://www.fao.org/ag/agp/AGPC…, or this one on livestock and poverty reduction http://www.fao.org/docrep/015/…, or this one on dry lands pastoral systems and climate change ftp://ftp.fao.org/docrep/fao/0…, or this general overview of livestock in the food system, which certainly does not contemplate a move toward global vegetarianism, much less veganism http://www.fao.org/docrep/012/…, or finally this report on “Agroecology and the Right to Food” by UN Special Rapporteur Olivier De Schutter presented to the UN Human Rights Councilhttp://www.srfood.org/index.ph… .
Before you start lecturing ME about living “in the real world,” you’d better become better informed yourself and consider how “realistic” or even desirable global veganism or even global vegetarianism are. Fine, be a vegan or vegetarian yourself if you want. Who cares? But don’t kid yourself that it’s the path to global sustainability or food security.