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Cats and Dogs: We Love You But Not Your Carbon Pawprint!

29 Apr 2021 6:24 PM | Gayle Marsh (Administrator)
  Who could resist this face?
If you’ve spent time outdoors in Marin lately, you’ve probably noticed that you have a lot of furry new neighbors. During the pandemic, many of us have added a dog or cat to the household for companionship and diversion.

Pets are wonderful but also pose some challenges, as you know if you’ve ever had a cat sit on your keyboard during a Zoom call. But what about the environmental impact of these beloved family members? 

Let’s take a quick look at the challenges and how you can overcome them.

Cats and Dogs Like Meat

Relaxing on a lazy pandemic morning  

You’ve probably heard about the carbon footprint created by our meat-centric diet in the US. Compared to a plant-based diet, meat requires more energy, land, and water to produce, and has greater environmental consequences in terms of erosion, pesticides and waste. Previous studies have found that livestock production produces the equivalent of 260 million tons of carbon dioxide in the US. 

What about pets? In a paper published in 2017, UCLA geography professor Gregory Okin calculated that meat-eating by dogs and cats in the US creates the equivalent of about 64 million tons of carbon dioxide a year. 

To put it another way, if the 160 million dogs and cats in the US were citizens of their own country, their nation would rank fifth in global meat consumption, behind only Russia, Brazil, the United States and China. 

This is no “back-of-the-envelope” calculation! 

  Gnome-based protein    

Can Fido and Fluffy Survive on Tofu Burgers?

Should you consider a vegetarian diet for your dog — or maybe even go vegan? Dogs are omnivores, so they are capable of extracting key nutrients from plant-based sources. However, cats are carnivores. Their health will suffer if their diet is limited to plants.

For instance, dogs and cats cannot make vitamin D in their skin like humans do, so it needs to be in their diet. Dogs can extract vitamin D2 from plants, but cats really need D3, which is only found in animal sources. 

So if you go this route, be very conscientious about planning a balanced diet for your pet, and monitor their health carefully.

What Else Can You Do?

    C’mon, this little Dumbo rat is cute
There are other ways besides going vegetarian to reduce the carbon footprint associated with pet food.
  • Buy pet food in bulk to reduce wasteful packaging or cook your pet’s food from scratch. I used to cook for our family dog, Willy. It wasn’t too hard to make a pot of rice and mix it with cooked turkey burger and some vitamin supplements. 
  • Don’t create a chunky kitty (or dog)! Just by reducing pet overfeeding we could significantly lower meat production in the US.
  • Don’t give your dog prime rib! As pet pampering has increased, pet food is increasingly made with high-end meat. Professor Okin encourages us to make a commitment to snout-to-tail consumption as much as possible.
  • Consider a vegetarian pet, like a goat, bird, or rat! Rats (domestic ones, not the kind that run around in the ivy) are much smarter than hamsters or rabbits and don’t smell bad like pet mice. (Don’t ask me how I know all this…)

Facing the Icky

If you have spent any time on Nextdoor you know that few issues rile up readers more than dog poop disposal habits (i.e., is it OK to put bagged poop in someone else’s garbage can). I will focus here on the environmental impact of how we dispose of pet waste.

Problems With Dog Poop

“I’d prefer if you didn’t discuss my poop”  

First, let’s face the cold, hard facts. With dogs, inevitably, comes poop. One source I found stated that dogs in Marin generate 11 million pounds of waste per year. If the owners pick it up, most of it goes in the landfill along with the plastic bags that are used to collect it.

Here I turn again to Dr. Okin at UCLA, who writes, ”If all of the feces from US dogs and cats, not including kitty litter and bags, were disposed as garbage, their feces would be equivalent to the total garbage produced by 6.63 million Americans, or approximately the population of Massachusetts.”

Dog waste is considered to be an environmental pollutant by the Environmental Protection Agency because it can harbor viruses, bacteria and parasites — including harmful pathogens like e coli, giardia and salmonella. Studies have traced 20 to 30 percent of the bacteria in water samples from urban watersheds to dog waste. 

In most cases, people prefer to pick up dog poop with plastic bags. It’s pretty well established that plastic bags contribute tremendously to our plastic trash problem. In the US, 14 billion plastic bags are consumed annually. These bags can have devastating effects on wildlife, especially marine animals like whales and sea turtles. For more, take a look at my prior posts on plastics.

The plastic bag is never going to be a good candidate for recycling. The economic realities of cheap new plastic production and low-cost oil and gas production make mechanical and chemical recycling processes economically uncompetitive and impractical at commercial scale. 


What about “compostable” pet waste bags? 

Some pet waste bags, like Biobags, are made from renewable sources like cornstarch. They are not, however, compostable except under special conditions. Composting requires specific levels of heat, water, and oxygen. But local landfill usually cannot provide these conditions. 

Nor are they accepted at composting facilities in many communities! 

In Marin, most green waste is delivered to WM EarthCare in Novato. WM EarthCare does not accept Biobags because they do not meet their standards for organic material. 

So if you are served by Marin Sanitary Service, Tamalpais Community Services District, Mill Valley Refuse, Recology Sonoma Marin, or Novato Disposal — all of whom use WM EarthCare — you should not put “compostable” green pet waste bags in the compost bin. 

The green waste from the communities of Sausalito and Marin City served by Bay Cities Refuse is delivered to the compost facility in West Contra Costa County; this facility accepts BioBags.

Source: Screen shot of WM website.

Moreover, because of the aforementioned bacteria and other gross stuff in dog poop, pet waste in a biobag can’t be publicly composted even if a facility has the capability of dealing with the bag! 

  Pilot project with digester in Cambridge MA  
  Composting Corgi waste at home  

Wave of the Future? Convert Poop to Energy

Dog waste can be anaerobically digested — a process that breaks down organic materials, producing a biogas that can be used for energy and a residue that can be used as a compost on plants. California has funded over 100 digester projects on dairy farms, with significant reduction of methane emissions from cow manure. Straus Family Creamery is one particularly successful example because the digester is one dimension of a multi-pronged approach to the environmental problems associated with the dairy business. 

This technology can be adapted for processing dog waste and is being tested in several pilot projects with anaerobic digesters at dog parks in the United States. 

In the Meantime, What Else Can You Do?
  • Flushing dog poop down the toilet is OK in some sewage facilities. Check out the situation in your area if you want to try this.
  • Composting is possible in some situations. Municipalities with curbside composting programs typically discourage people from putting dog waste in their compost bins. Composting dog waste in a backyard bin can be iffy. It's hard to achieve the temperatures needed to kill off pathogens but give it a try if you are looking for a project.

Problems With Cat Litter

Cat practicing jazz hands  
Increasingly, Americans are keeping their cats indoors for their own protection as well as that of the bird population. In my youth, the problem was keeping cat poop out of the sandbox. Now cat owners have to think about disposal of cat waste and cat litter from in-home litter boxes. 

I imagine most people are OK with scooping used cat litter into a paper bag rather than a plastic one for disposal. But the litter itself poses a different problem. I am out of poop-related visual imagery, so I leave it to you to imagine all the waste and litter generated by the 90 million or so cats in the US (equivalent of the Great Wall of China stretching from San Francisco to Manhattan????)

More recently, companies have developed better options that use renewable resources like corn, grass seed, and wheat. Others are made of wood chips or recycled newspaper. Frugal cat owners might consider making their own cat litter by repurposing everyday materials that would otherwise end up in the waste stream. Plain sawdust apparently makes good cat litter, or you could make cat litter from old newspapers if you are crafts-oriented. 

That’s it for this post! If you want to read more about pets and the environment, check out this recent article.

Thanks to Rob Badger and Nita Winter
for sharing Rob’s beautiful image. 
Check out their award-winning book or
visit their website to see more!


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