[belorn]

If we stopped all fishing, you would end up with quite a lot of decreased biodiversity in lakes from eutrophication, cause by those farms that supply that vegan diet. I know, because I know fishermen who got paid by the Swedish state to do just that.

We could demand that farms had zero carbon footprint, zero water usage/drainage, a new tree for every cut one, and no pesticides. It is expensive, and food labeled under a mission which try to cover some of those aspects do demand a much higher price. At best it can be said is that its has a lower environmental impact that cows, even through my government (Sweden) explicitly says that if we don't get more farmers, most of the open field and bio diversity that comes from open fields will be lost.

Personally, I would go with a omnivore diet that pay a little extra (ie about double vs the cheapest) for products under environmental focused labels, and then just eat less of it. Even better, skip that car and you will end up having a much lower carbon footprint than any car owner has, regardless of diet.