The problem is the misuse of the word "vegan". Veganism is a moral philosophy. It is more like feminism than like vegetarianism. Veganism has to do with animal rights and liberation. That has consequences on the diet a person eats but also all other things a person does and doesn't do. None of these studies are concerned with or discuss the rights or experiences of animals, so they aren't about veganism. It's a relatively small thing except that veganism is so poorly understood, so extra diligence is always appreciated.
The study is about diets and their consequent impact on GHG. Why does it matter that it's not about philosophy?
The problem is the misuse of the word "vegan". Veganism is a moral philosophy. It is more like feminism than like vegetarianism. Veganism has to do with animal rights and liberation. That has consequences on the diet a person eats but also all other things a person does and doesn't do. None of these studies are concerned with or discuss the rights or experiences of animals, so they aren't about veganism. It's a relatively small thing except that veganism is so poorly understood, so extra diligence is always appreciated.
The study is about diets and their consequent impact on GHG. Why does it matter that it's not about philosophy?