The core issue is soil quality. Without sufficient organic content in the soil, all our food, whether it be plant or meat, has drastically reduced nutritional content meaning we need to consume more for the same effect. We're heading for a global food shortage because of the one key issue. Healthy soil also sequesters an enormous amount of carbon from the atmosphere. So instead of fighting the beef vs tofu wars, we should be focusing on encouraging agricultural practices that enrich soil rather than destroy it. We have about 50 years of crop cycles left before the majority of arable earth turns to sand.
Shifting your diet to be more plant-based is a good idea, but it's not the crux of the issue.