According to the United Nations, animal agriculture is responsible for 18% of greenhouse gas emissions. According to WorldWatch, the figure is much higher — 51%.
Transportation exhaust is responsible for 13% of greenhouse gasses.
And when you consider the other environmental effects — water use/pollution, soil erosion, etc., and the fact that methane is much more destructive than CO2 in a 20 year time frame, animal agriculture is even worse.
So XR can focus on carbon emissions because XR doesn’t want to promote veganism. But that is, simply put, irrational.