Agriculture is such a big contributor to greenhouse gas emissions. If you stop eating meat especially beef then you could rewild the land and this is exactly what's happening in the Amazon. They're chopping down trees to put on cows so the effect is doubly bad because you get rid of your carbon sink and you put a farting cow on it. What about insects? Would you switch to eating insects? I'm sure I eat lots of insects by accident as we always have mites in our cupboard. So spiders grow into your mouth.