Ranchers are experts at raising cattle. The ones I’ve met are proud of their beef. What about the hides, where leather comes from? What is the impact of producing leather, or not producing leather, on the environment? Farmers and ranchers have two choices when dealing with hides, they can either throw them out or convert them to leather. Most, but not all, hides in developed countries are converted to leather. For example, in the US, while it can vary, these days it is probably about 85%. In many countries, including South Asia and Africa, hide use may be 70% or less.
Recently, I did a back of the envelop estimate of how many hides go to waste. Globally there are almost a billion animals. Numbers are hard to come by, but estimates are that that about 300 million are slaughtered annually, mostly for meat consumption. To estimate what percentage of the hides of these slaughtered animals go to leather I talked to people in the trade all over the world, including in Australia, China, Europe, India and the US. Based on these conversations I estimated that of these 300 million animals, about 177 million of their hides, or about 60% of global slaughter, were converted to leather. That means about 123 million hides, or about 40% of slaughter go into landfill.
What is the likely environmental impact of the hides that go to landfill? Again, there is not a lot of information about what happens to leather that ends up in landfill. There is some research on how long leather takes to decompose, but nothing immediately available on hides. I found that the US Environmental Protection Agency had evaluated how much different CO2 equivalents were generated by a wide variety of waste, from wood to food products. Unfortunately, cattle hide was not included. When I then spoke with materials scientists what leather would be most like on the list, they suggested its fiber and protein composition would make it most like food waste. In fact, this might be a bit conservative. According to the EPA?s greenhouse gass reductions calculator, one metric ton of food waste decomposes and produces approximately 0.88 metric tons of greenhouse gas equivalents. 1
If 123 million hides go to landfill, I wanted to know how many metric tons of greenhouse gas that was producing. I spoke with packers that sell hides and manufacturers in the leather tanning industry about average weight of hides and conversion ratios. The conversion ratio depends on the size of the animal and animal husbandry practices. The number I got was a global average for hide weight would be about 25 kilograms. Or a 123 million hides is more than 3 million metric tons of hides. That means 3 million metric tons of hides is about 2.7 million metric tons of greenhouse gas equivalents. That’s the environmental impact of the waste.
What about the environmental pollution reductions from converting hides into leather? By my estimates, there are approximately 177 million hides used for leather. Converting to tons, that is more than 4.4 million metric tons of hides. And converting that to greenhouse gas equivalents, that is more than 3.89 million metric tons. In other words, by pulling hides out of landfill and turning it into clothes, furniture and automobile upholstery, we are pulling more than 3.89 metric tons of greenhouse gas equivalents out of the environment every year.
This doesn’t answer all the questions. There is an environmental footprint to converting hides to leather and for converting leather to a consumer product. Arguably, the sustainability metric for the manufacturing process would be similar for any similar input (e.g., a leather sofa vs. a cotton sofa). It would be nice to know what the environmental footprint for the tanning process is, and I understand that the leather industry is looking at getting this information. In the meantime, since I like to eat meat, I am going to do my part and prefer leather when I buy shoes, belts, bags and other leather friendly items.