The United States of Fido and Fluffy would rank fifth in global meat consumption if American dogs and cats formed their own country. Given the outsized impact of meat production on global warming—animal agriculture accounts for 14.5% of total greenhouse gas emissions—pet ownership should be classified as a climate no-no alongside transcontinental flights. (According to a 2020 study conducted by the University of Edinburgh, the pet-food industry ranks second only to the Philippines in terms of total emissions.) Assuming that the majority of pet owners would prefer to avoid flying over Fluffy, a new study published today in Scientific Reports offers an alternative for environmentally conscious owners. It turns out that the type of food—wet or dry—has a big impact on pet food emissions.
A group of researchers from the University of Sao Paulo evaluated the greenhouse gas emissions of different dog and cat diets in Brazil, which is second only to the United States in terms of dog ownership and fourth in terms of cat ownership, in their paper, Environmental Impact of Diets for Dogs and Cats. They also investigated the nutritional and calorific values of commercial dry-food diets, wet-food products, and home-made pet meals while considering land and water use.
Wet food has the greatest environmental impact, emitting up to seven times as much carbon as a dry diet of kibbles or biscuits. According to the authors, a medium-sized dog weighing 22 pounds (10 kg) and eating wet food would emit 6,541 kilograms of CO2 per year, the equivalent of 13.5 round-trip flights in Europe. A dry diet for the same dog would result in 828.37 kilograms of CO2, which is equivalent to 1.7 European jaunts. That is without considering transportation and packaging, which would almost certainly have a greater impact given the increased weight and life cycle of aluminum cans used for wet food versus paper bags used for dry food.
However, not all kibble is created equal in terms of climate. According to the University of Edinburgh’s study of pet food’s carbon footprint, dry food derived from meat contributes up to 2.9% of agricultural CO2 emissions. While omnivorous dogs can survive on a plant-based diet, cats require animal protein. Pet food companies, including majors like Mars and Purina, have developed protein-rich, insect-based foods for both dogs and cats to meet this demand. Jiminy’s, a pet food startup in the United States, sells both cricket kibble and Good Grub, a worm-based version. Because, Animals, a U.S.-based biotech company, is growing cultivated meat from mouse and rabbit stem cells to make freeze-dried pet treats, which could be available in supper bowls soon.
However, the environmental costs of shipping will continue to be an important consideration. Bottom line: Whether it’s cricket chow today or cultivated mouse in the future, the key to a climate-friendly pet diet is keeping it kibble-based.