Cows convert CO2 into methane. CO2 stays in the atmosphere for hundreds or even thousands of years. Methane only stays in the atmosphere for at most 12 years. Because we had cows on this Earth in the 60s, there is far less CO2 and greenhouse gasses in the atmosphere today. It's the same with the cows we had in the 70s, 80s, 90s..... By having as many cows as possible today, our children and our grandchildren will live on an Earth with far less greenhouse gasses in the atmosphere.