That's "CO2e" (CO2 equivalent, measured in global warming potential), not CO2. The time scale isn't specified, despite making a big difference in some cases, so I'll assume it's calculated over 20 years, which seems to be the most common. It's important to distinguish CO2 from CO2e, because a large part of CO2e emissions from animal farming are methane, which is a more potent greenhouse gas than CO2. Methane emissions could be reduced in multiple ways, e.g. we could switch to farming kangaroos, which don't produce methane, or supplement cow feed with seaweed, which was found to dramatically reduce methane production:

https://journals.plos.org/plosone/article?id=10.1371/journal...