A dog weighing 15 kilograms produces some 8.2 tons of CO2 over the course of a 13-year lifespan. This is the conclusion of a life cycle assessment for an average dog conducted by Kim Maya Yavor and Dr. Annekatrin Lehmann and headed by Professor Dr. Matthias Finkbeiner of the Chair of Sustainable Engineering. “These 8.2 tons of CO2 are the equivalent of 13 return flights from Berlin to Barcelona and almost as much as the CO2 emitted in the production of a mid-class luxury car, such as a Mercedes C250," Professor Finkbeiner explains. The ton of fecal matter and 2,000 liters of urine produced by a dog over a lifetime of 13 years further impact the environment. “The scale of the impact really surprised us,” says Finkbeiner.
This is the first life cycle assessment covering all aspects of a dog’s life - from feeding through to the excrement it produces. The researchers based their calculations on a dog weighing 15 kilograms living for 13 years. The calculations include the raw materials used for a dog’s food, the resources required to produce it and the resources used in its packaging and transport as well as the environmental impact resulting from a dog's excrement, the production of the plastic bags used to scoop it up and the resources required to clean the streets – in other words, all the materials and energy sources required to make a product and their impact on the environment.
To provide an example of the scope of the life cycle assessment, the impacts of soy products from Brazil used in the production of dog food were included. “What makes our life cycle assessment unique is our focus on the environmental impact of every aspect of the food a dog consumes over the course of its life as well as the impacts for the environment of its urine and excrement,” says Finkbeiner. It is precisely this focus on excrement and urine that was missing in previous life cycle assessments.
Dog food and excrement are the two factors which most damage the environment. “We examined 15 indicators, or environmental impact categories, for our life cycle assessment. These include climate change, ozone depletion, smog, the eutrophication of water bodies, the acidification of soil, the ecotoxicity of freshwater, and land use. At approximately 90 percent, dog food is the major harmful factor in almost all these parameters. However, 90 percent of the damage within the category freshwater eutrophication is caused by a dog’s urine and excrement. And half of freshwater ecotoxicity (in other words poisoning) results from excrement.
“As no material data was available regarding dog excrement, we had to commission analyses to ascertain the quantities of phosphorous, nitrogen and heavy metals excreted. Phosphorous and nitrogen have a considerable impact on eutrophication, in other words the increase of unwanted nutrients in bodies of water, and heavy metals are significant for the poisoning of soil,” says Finkbeiner. In their study entitled “Environmental Impacts of a Pet Dog: An LCA Case Study”, Kim Maya Yavor, Annekatrin Lehmann and Matthias Finkbeiner conclude on the basis of these figures that scooping and appropriate disposal of dog excrement contribute significantly to the protection of nature. “The additional environmental damage resulting from the production of the plastic poop bags is significantly lower than that caused when excrement is introduced directly into the environment. This is also demonstrated by the figures we have collected.”
It was the sheer scale of their findings that really shocked the researchers. “Every time industrial meat production comes in for heavy criticism in the context of the coronavirus, we should also bear in mind that one of the most beloved pets in Germany is fed using precisely such industrially produced meat.
The meat used in the production of dog food isn’t sourced from an organic farm in the Uckermark or from a Bavarian Alpine meadow. It comes from factory farming with all the social and environmental ills we associate with this,” says Finkbeiner.
He also refers to another figure to demonstrate the increasing environmental impacts of dogs: The number of dogs in Germany has more than doubled since 2000. In 2019, there were 10.1 million dogs compared to just five million in 2000. The last five years have seen an annual increase of more than 650,000 dogs.
The 8.2 tons of CO2 produced over 13 years equate to an annual CO2 emission of 630 kilograms. “If we place these 630 kilograms of CO2 in the context of the two tons per year indicated as environmentally acceptable for humans by the Intergovernmental Panel on Climate Change, then every dog owner can see that almost one third of their CO2 budget is already used up by their dog.”
Finkbeiner and his two colleagues also created a life cycle assessment for a dog weighing 7.5 kilograms living for eight years (three tons of CO2 emissions in a lifetime) and one weighing 30 kilograms and living for 18 years (19 tons of CO2 emissions in a lifetime). Their conclusion: Just as with cars, a small dog is better for the climate and the environment than a large dog. In other words, if you want a dog, then it is better to go for a dachshund than a Great Dane.
“Environmental Impacts of a Pet Dog: An LCA Case Study” emerged from the research conducted for the life cycle assessment of a human, also produced by the Chair of Sustainable Engineering.
Open source study “Environmental Impacts of a Pet Dog: An LCA Case Study”