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A New Study Ranks the Climate Pawprint of Different Types of Pet Food

If American dogs and cats made up their own country, the United States of Fido and Fluffy would rank fifth in global meat consumption. Considering the outsize impact of meat production on global warming—animal agriculture accounts for 14.5% of total greenhouse gas emissions—pet ownership should rank alongside trans-continental flights in terms of climate no-nos. (A 2020 study by the University of Edinburgh places the pet-food industry just behind the Philippines when it comes to total emissions). Assuming that most pet owners would rather give up flying over Fluffy, a new study published today in Scientific Reports offers an alternative for climate-conscious caretakers. It turns out that the kind of food—wet or dry—has a significant impact on pet-food emissions.

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In their paper, “Environmental Impact of Diets for Dogs and Cats,” a group of researchers based out of 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 when it comes to dog ownership, and fourth globally for cats. They also included land and water use in their investigation of commercial dry-food diets, wet-food products, and home-made pet meals while considering the nutritional and calorific values of the different diets.

Wet food has the greatest environmental impact, contributing up to seven times more carbon emissions than a dry diet of kibbles or biscuits. The authors estimate that a medium size dog of 22 pounds (10 kg) eating wet food would be responsible for 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 emit 828.37 kilograms of CO2, approximately 1.7 European jaunts. And that is without factoring in transport and packaging, which would likely have a further impact given the increased weight and life cycle of the aluminum cans wet food usually comes in compared to the paper bags in which dry food typically is shipped.

But not all kibble is equal, climate-wise. The University of Edinburgh’s study of pet food’s carbon pawprint estimates that dry food sourced from meat contributes up to 2.9% of agriculture’s CO2 emissions. While dogs, which are omnivorous, can survive on a plant-based diet, cats require animal protein. To feed that need, pet-food companies, including majors like Mars and Purina, have developed protein-rich, insect-based foods for both dogs and cats. In the U.S., pet food startup Jiminy’s sells both a cricket kibble and a worm-based version called Good Grub. A real-meat-without-the-guilt option could be in supper bowls soon: one U.S.-based biotech company, Because, Animals, is growing cultivated meat from mouse and rabbit stem cells to make freeze-dried pet treats.

That said, the environmental costs of shipping will remain an important consideration. The bottom line: Whether it’s cricket chow today, or cultivated mouse in the near future, the key to a climate-friendly pet diet is making sure it stays in kibble form.