The Green Stars Project

The carbon footprints of plant-based milks

How do plant-based milks compare in terms of sustainability? I’ve written about this before, with this post comparing the crops that go into vegan milks, a post on regular versus organic dairy, and another on conventional milk versus plant-based milk. Here, I want to specifically look at the carbon footprints of various plant-based milks, versus dairy milk.

I recently came across a paper titled, Life cycle assessment of California unsweetened almond milk, and thought I would use it as an opportunity to provide an update on plant-based milk. The study, conducted by researchers at the University of California at Davis and UC Santa Barbara, focused on the impact of almond milk made by a local company, Califia Farms, but it also includes useful information on plant-based milks in general.

Comparing the carbon footprint of plant-based milks

The researchers examined several sustainability factors, including a key metric: global warming potential (GWP), which is pretty much the same as carbon footprint. Table 5 is a useful resource as it shows the carbon footprints of various plant-based milks (with data collected from several studies) – this is basically the amount of greenhouse gases generated during farming and processing of the milk. This doesn’t include the carbon footprint of packaging as this will vary a lot from brand to brand (more on the packaging footprint later). I’ll represent some of the data from Table 5 as a graph here, for convenience.

The carbon footprint of various types of milk here (expressed as kg CO2 produced per 48 oz. of milk produced). The carbon footprint is divided into the CO2 produced during farming and the CO2 produced during processing of the finished milk (except for coconut milk, where only the total footprint data was available).

There are two things to note from this data:

  1. The carbon footprints of most plant-based milks are similar, and all of them are significantly lower than that of cow’s milk.

The researchers compared their own values for the carbon footprint of almond milk to those of three other studies and found that they are in close agreement, ranging from 0.39 to 0.58 over the four studies. (The units are kg CO2 equivalents per 48 oz. of milk produced, without packaging.) The carbon footprint values for other milks – oat, soy, coconut and pea – are also within this range.

The authors also include data from five papers that looked at the impact of conventional dairy milk and the carbon footprint values agree well, ranging from 1.7 to 1.97. So, comparing these values, you can see that conventional dairy milk has a carbon footprint that’s three to five times higher than almond milk and most other plant-based milks.

2. The carbon footprint of processing a plant crop into milk is higher than the footprint of growing that crop.

The processing part accounts for somewhere between 70% and 90% of the plant milk’s carbon footprint, with only 10-30% of the footprint due to farming. This has two implications:

A. The sustainability of company that produces the milk is important.

B. You can reduce the carbon footprint of your plant-based milk by making your own.

Packaging footprint of Califia almond milk

Remember that the data above looks at the carbon footprint (GWP) of producing milk without packaging, in order to equalize the comparison. When the researchers looked at the footprint of a finished bottle of Califia almond milk they found that the packaging contributed 43% of the product’s final carbon footprint. This isn’t too surprising as the Califia packaging really is super bulky! You can see this data in Figure 2, and I’ve shown it below as a pie chart. As we saw in the graph above, the carbon footprint of producing Califia almond milk was 0.39 kg CO2 per 48 oz. of milk. The carbon footprint of the packaging is 0.31 kg CO2 for the 48 oz. bottle (shown below), or 43% of the final carbon footprint of 0.71 kg CO2 for the bottled milk that you’d find at the store.

Note that this final carbon footprint number (0.71) is still much lower than that of cow’s milk (which was at least 1.7 for just the milk, not including packaging). So there’s still a large carbon benefit to choosing almond milk.

The takeaways for consumers are similar to those above. The sustainability of company operations (in this case, choice of packaging) is again very important. You can definitely reduce the carbon & material footprints by making your own milk and avoiding packaging.

So the research paper has helped shed light on three aspects of the impact of milk:

  1. Plant-based milks have a much lower footprint than dairy milk.
  2. Processing a plant into milk accounts for a large part of the carbon footprint.
  3. Packaging can add a large amount to the carbon footprint of any milk.

Impact of Califia milk packaging

The researchers made a suggestion to Califia Farms for reducing its carbon footprint and other impacts: switch to lighter packaging that’s made from recycled plastic. Califia’s competitor, Ripple Foods already uses post-consumer recycled PET (rPET) for its Ripple milk packaging.

The chart above shows results of analysis (in the same paper) that the carbon footprint of Califia Farms milk would be significantly reduced by replacing the current packaging with a bottle made from recycled plastic (rPET). Perhaps even more important than reducing the carbon footprint, the incorporation of rPET into the packaging would divert waste from landfill and help create a market for recycled plastic.

If we want to keep using plastic packaging in such large quantities, then it really has to be recycled more, and the only way in which recycling works is if there’s demand for recycled plastic fibers. Califia does try to make recycling a little more efficient by making the label easy to remove, but it needs to step up and use rPET for bottles. Or, going a step further, why not introduce reusable glass bottles with a large deposit to encourage returning to stores? Straus Family creamery in Marin has implemented this system successfully for years.

Of course, carbon footprint is only part of the equation in determining if a product is sustainable and ethical. In the next post, I’ll take a look at other aspects of this, sticking with the example of Califia Farms.

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