I didn't eat meat for 30+years, then realised it was not a good option for everyone.I had started non-meat low carbing, then got pancreatitis, so I was very ill and now Type3c. I doubt if I would as done as well, if I had not have eaten meat, I needed concentrated protein for my body to heal. No way could I have eaten enough plant based protein.
I think eating meat could save the plant, maybe eating less of it, we do not need as much as we do eat to supply our protein requirments. If we have less land for food production, if sea levels rise, the land we use will perhaps have to be intensively farmed, even if its plants based, and and that means more nutrients and moisture retaining waste will be needed, even if its only from the human animal and as far as I know we can not grow soya in the UK
Soy, palm oil, coffee and avocado production are all clearing rainforests, and of course the amount of carbon emitted by China, which is the largest producer is never mentioned, which we have no control over. No one seems to want to tackle the emmisions from cars and planes, and I bet most of the attendees at the Globes did not arrive by bus, and the USA is also a big producer of carbon emmisions. If they had all turned up in a clothes recycled from a thrift shop perhaps that would have really have shown a real visable commitment.
https://en.wikipedia.org/wiki/List_of_countries_by_carbon_dioxide_emissions
The UK import more soya for human food than for animals, a lot of animal feedstuffs are byproducts of human food production. Bread, biscuits, beer and sugar making byproducts, then there are carrots, potatoes and other human food deemed not good enough for supermarket shelves.
https://www.bcva.org.uk/system/files/whatwedo/BBC Programme BCVA Statement 19.12.19.pdf
Mostly cows and sheep are fed on grass, and a big up for our traditional breeds, they will survive and thrive on very poor quality grass or in the case of North Ronaldsay sheep, no grass at all, they can live off seaweed.
https://en.wikipedia.org/wiki/North_Ronaldsay_sheep
I think this provides a really good overall study of plant v meat and its implications.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5715743/
but looking how quickly our own food growing climate is changing things may change sooner rather than later. Its been to wet for some farmers to harvest or plant, even if they haven't had flooded land.