@Javier, I’m not being critical of your question, because it’s a great question. I do think that the Dhamma gives us most, if not all, of the tools needed to make these ethical and pragmatic decisions. To your question, we likely should be more inclined to eat much less, or no, animal meat. These factory farmed animals suffer greatly ( at least they do in the US) and it might be the most ethical position to take to avoid being part of that chain of commerce. If one chooses to eat animal meat, for dietary or other reasons, it seems that we assess this the way we must assess all kamma: is our intention wise and skillful, and if not, what is the dark kammic weight of choosing this course of action? Are there ways we can minimize the harm, even if we can’t eliminate it completely?
As with climate change and the harm being done to people, animals and habitats, it seems rational to contribute as little as we can to climate damage, and at the same time, work to engage others on as large a scale as possible to effectuate some mitigation of environmental damage. It seems to me that the 4NT give us a decision tree to work with issues about climate damage, such as cultivating right views, right intention, right action, etc.
It seems to me that if we really take this Dhamma to heart, it gives us the guidelines and inspiration to live wise, happy, minimalist, altruistic, and harm-free lives. It’s a template we can apply to almost any situation, time, or culture. That’s my two baht anyway.