It's also important to note for this discussion that dogs and cats account for around a quarter of emissions from animal agriculture: https://www.forbes.com/sites/jeffmcmahon/2017/08/02/whats-yo...
As obligate carnivores it is difficult to decrease the overall footprint of a cat. Pet ownership may be one of the biggest components to one's personal carbon footprint. I'm often dismayed by friends and colleagues my age who use environmental arguments for why they won't have children, yet own multiple animals.