That's a fairly simplistic argument though. Deforestation converts forest into a cattle feed monoculture. That plant material locks in less co2 than a forest. There's the extra CO2 emitted from growing cattle feed as opposed to growing food for humans directly (via fossil fuels used in production). And then there's methane, which is a more potent greenhouse gas.

It's a topic that's way more complex than you seem to think. Climate scientists did not miss the simple fact that all carbon in a cow originates from the atmosphere. That's understood. But there's all the other stuff.

For the record I'm not vegan or even vegetarian. Attacking vegans for their beliefs is poor formimo