George Monbiot uses a recent paper to argue that we should all give up meat and dairy because there are more efficient manners of growing a minimal diet. Quite possibly there are but then who wants to live a minimal life, subsist upon a minimal diet? The point is not existence but utility maximisation, no?
However, he is right about this:
The most important environmental action we can take is to reduce the amount of land used by farming.
As has been pointed out numerous times any form of organic farming requires more land than industrial such. Simply because, at root, industrial farming is the substitution of the products of factories and chemical vats for more land.
Though roughly twice as much land is used for grazing worldwide as for crop production, it provides just 1.2% of the protein we eat. While much of this pastureland cannot be used to grow crops, it can be used for rewilding: allowing the many rich ecosystems destroyed by livestock farming to recover, absorbing carbon dioxide from the atmosphere, protecting watersheds and halting the sixth great extinction in its tracks. The land that should be devoted to the preservation of human life and the rest of the living world is at the moment used to produce a tiny amount of meat.
Assume this is true, now, do we have any evidence that efficient farming does free up land for such rewilding? Actually, we do., New England. A century and a half back the area was a quiltwork of small farms. The forests we go to gawp at in autumn didn't exist, they'd been clear cut. What we do go to see these days is almost entirely new growth. Rewilding that has occurred as a result of mechanical farming and the railroads opening up the mid-West.
We get our food from the more efficient land and production methods these days. The contention that doing so allows rewilding is proven. Which is why we should indeed be using those industrial farming methods, precisely and exactly because they reduce our call upon the land, leaving more of it for other forms of life - and for us to go gawp at.
If your argument is that we should eat a particular way in order to reduce the land we use to feed ourselves then you are indeed arguing against organic farming and in favour of industrial such. Odd how the usual suspects tend not to make the connection, isn't it?