Having been a vegan for more than 20 years I have to disagree with many points here. There are many fallacies with environmentalism, but this is not one of them.

Meat production, in the form of methane production, amounts to about 6% of green house gases. This is not insignificant. (California actually flew planes over ranches to map methane production.)

Secondly, land-use is very important. The Amazon rain forests have been systematically cut down to make way for cattle ranches. This meat is shipped primarily to Europe. European meat consumption is directly responsible for the destruction of the Amazon rain forest.

California is instituting all electric vehicles to include freight trucks, starting next year. Gas vehicles will be phased out by 2035. It is doubtful that agriculture in California will survive that long. Environmental regulations will kill the industry soon. Agriculture will shift to overseas production. Maybe South America.

From a philosophical point of view, we need to move from a 'mental' world view to an 'integral' world view ( as defined by Jean Gebser). Veganism may not make logical sense to the 'mental' world view, but it makes perfect sense to the 'integral'. We need to see the planet as one ecosystem, not as a natural resource for capitalist production.