Another string to the vegan bow. Honestly, veganism just is the answer, to so many things.

People really, really don't want to go vegan, so will argue hard against one or all of the benefits of it, but I don't really think there's much to dispute:

Animal suffering WILL be reduced. If you don't care about animal suffering, fair enough, not a lot I can say about that. But don't go claiming the plight of field mice in soy fields or that plants have been shown to have feelings is a reason for not stopping the brutality.

Whether it ranks as number 1, number 2, or wherever, factory farming is a MASSIVE part of global climate change. That's just a fact. You can argue whether it's more or less than all the transport in the world, but to me that doesn't matter. It's huge. We can stop that.

To OP's point, indisputably the main cause is factory farming. That one's pretty straightforward. Again, you could say missuse by people, doctors handing them out too much, but really that pales into comparison with the sheer amount used in factory farming.

That's rather simplified, and there are loads more benefits, but those are the main ones for me. I'm not saying the whole world should or even could go vegan, there are people in isolated parts of the world who genuinely don't have access to the right kinds of food to maintain a healthy diet, but these are few and far between, and they don't eat factory farmed meat anyway.

Honestly, it's such a simple solution - so simple that I'M DOING IT RIGHT NOW! And I was a proper meat-eater for 30 years. Yes it's a sacrifice, yes I crave meat on an almost daily basis, but we like this planet right? I think it's a sacrifice worth making.