For most of the people there cows are sacred animals.
The real question is (for some reason not framed this way): how many ruminants us humans want to keep around and where? If less than now how fast we need to kill those animals?
Tomorrow we could have 100% of grassland completely devoid of ruminants and other grazing animals, wild or not.
What will really happen to ecosystems and climate if we do this? Do we have a previous point in history where that was the case? Are our models good enough to say it will be 100% positive as we expect?
And I you looks at methane emissions globally ruminants are far from the leading emitters, why not go more intensely after other sources incluing the fossil fuel industry (leaks & all) that are fully man made, non renewable and useless, rather than trying to convince India people to slaughter all their sacred cows instantly?
Wetlands are a large source of methane emissions, should we dry those lands? Same question about ecosystems and full climate impact.
I understand vegan use this as a talking point, but when you look at the big picture there seem to be more reasonable choices and compromises based on data than ruminant extermination.
5. If I change my food preferences, this will have a tangible impact on both global warming and future generations.
A. Not changing your habits even a bit, and having the planet all fucked up in 100 years; or
B. Drastically changing your habits, and having the planet all fucked up in 100 years and three hours,
what would you choose?
I think this is just due to a lack of understanding or acceptance, because the nature of the problem makes it difficult/impossible to prove (X will lead to Y on date Z). I'm sure there are people who on principle hold personal freedoms above all else, but I think most people could change because they agree with the line of reasoning:
1. My consumption of meat contributes to demand for cows
2. Cows produce methane, which is a potent GHG
3. GHGs are causing global warming
4. Increased global warming is bad for future generations
They just question or fundamentally disagree with one or more of the premises.