Tea’s Low Carbon Footprint—Until You Heat the Water

The snowfall record was smashed in Ann Arbor.

This past Monday. Forty days before winter officially begins. Before some of us had raked the leaves. Or cleaned the gutters, cleared the garden, taken in yard furniture, even removed the jack o’lanterns.

This unprecedented 11 inches of snow in early November yet again demonstrates current climate unpredictability.

And further increased our collective carbon footprint as many of us—with traffic at a standstill and snow continuing to pile up around us—sat in idling cars and buses for literally hours.

Giving us plenty of time to think about what we’re doing to our environment, and just maybe coming up with a few ideas about what how we can change our habits.

So what about my habit of drinking tea morning, noon, and night?

I’ve often wondered about tea’s carbon footprint seeing that the leaves I brew have been grown across the globe from my home.

Conveniently, Andrew, a middle schooler here in Ann Arbor, recently looked into this for a school project and sent me this link—Climate change food calculator: What’s your diet’s carbon footprint by BBC News—thinking this would make a good blog post.

So thank you, Andrew! Especially since the news for tea drinkers is actually very good!

Looking at Tea’s Carbon Footprint

This calculator says that my tea habit (twice a day or more) contributes 30 kg of greenhouse gas emissions per year, which is equivalent to driving a car for 78 miles or heating a house in the UK for 4 days. Negligible!

If I were to drink the same amount of coffee, I would be contributing 311 kg per year (795 miles driven/49 days of heat), whereas if I were to eat beef only 1–2 times a week, my damage would be a substantial 604 kg/year (1542 miles driven/95 days of heat plus the amount of land equal to 6 tennis courts).

Of course there are many parameters to consider when trying to calculate exactly how much impact an individual’s actions will have on the environment. This calculator is based on global averages, and developers Joseph Poore (University of Oxford) and Thomas Nemecek (Agroecology and Environment Research Division, Zurich) were thorough in researching the 40 chosen food products:

They assessed the effect of these foods on climate-warming greenhouse gas emissions and the amount of land and fresh water used across all stages of their production, including processing, packaging, and transportation, but excluding the cooking process. [emphasis mine]

But You Have to Brew It to Drink It

A 2010 life cycle assessment by G. Doublet and N. Jungbluth to investigate Darjeeling tea’s environmental impact incorporated Nigel Melican’s 2009 presentation of carbon footprint research, which included the process of brewing the tea.

The study focused on the environmental impacts of tea vs coffee cultivation, tea manufacturing, tea packaging, and tea preparation.

Like in Poore and Nemecek’s calculator, the researchers found that the carbon footprint of a cup of coffee is higher than a cup of tea, around 5 to 7 times higher using the ecological scarcity 2006 method, which considers emissions into air, surface and ground water, and top soil; energy resources; natural resources; and deposited water.

Other factors at play include:

• cultivation (much higher for coffee)
• harvesting method
• difference in yield of coffee vs tea plants
• difference in amount of coffee berries vs tea leaves required to make a kg of finished product (more are required for coffee)
• processing steps (type and how many required; more are required for coffee)

You can easily see how difficult it is to actually compare coffee vs tea. For example, coffee beans are picked when they are ripe, whereas tea has multiple harvest times and different leaves (bud, new leaves, older leaves) are harvested depending on what tea is to be produced. Not to mention the myriad production methods possible for tea!

However, when brewing is also factored in, which means looking at the non-renewable cumulative energy demand,  coffee is only around 2 times higher than that of tea. Still, when evaluating data in this way, it’s important to realize that nearly all of tea’s energy demand occurs when the consumer boils the water to make their tea.

In fact, processing the leaves accounts for only 13–15% of tea’s total carbon footprint whereas boiling water in an electric kettle to brew the tea accounts for 64–73%! (The study does point out that automatic coffee machines are even less efficient than water kettles.)

The fact that my tea was transported from the garden to Germany for testing and distribution to the U.S. for me to buy? Very little contribution to the carbon footprint compared to other factors.

But That’s Not Always the Full Story

In another recent study, A. Hu and colleagues determined that adverse environmental impacts from consumer use—boiling that water!—is the main problem when looking at tea from Sri Lanka and Kenya, but in Taiwan, boiling the water was secondary to fertilizer use. And in Iran, machinery and diesel fuel were the primary contributors to tea’s carbon footprint.

But even that isn’t straightforward. For example, in Sri Lanka:

Their results showed that energy use was highest during the consumer use phase; CO2 emission was highest (44–47%) during the packaging phase; labor use was highest during the cultivation phase; and cost was highest in the cultivation and purchasing phases. (Hu et al. 2019)

The researchers then did a case study of Taiwanese Dongshang tea, finding that consumers making the tea—the water itself, boiling it, and wastewater—contributed the most to its carbon footprint as far as energy use, while fertilizers had the “biggest environmental impact in the human health category), and there was of course energy use during production (Hu et al. 2019). As you might expect, black tea production uses more energy and has a larger environmental impact than that for other types of teas.

The Takeaway?

Tea has a very low carbon footprint compared to other beverages and food.

Still, research such as that by Hu and team helps pinpoint specifically where that footprint is creeping higher, allowing the industry to rectify or at least reduce the issue. Hu et al. suggest strategically using organic fertilizers, using solar power for drying and withering, and improving the efficiency of boiling water.

At home, we can start by taking only what we need from our water tap and then boiling only the amount needed for brewing—and don’t add milk!

According the calculator, if you use one serving of milk a day (say, added to multiple cups of tea per day), you’re adding 229 kg to your annual carbon footprint. Which equates to 585 miles driven/36 days of heat plus 703 eight-minute showers and 2 tennis courts!

---

Sources:
–N. Stylianou et al., “Climate change food calculator: What’s your diet’s carbon footprint?,” BBC News, 8/9/19.
–G. Doublet and N. Jungbluth, “Life cycle assessment of drinking Darjeeling tea,” ESU-Services, July 2010.
–A. Hu et al., “Environmental Impact and Carbon Footprint Assessment of Taiwanese Agricultural Products: A Case Study on Taiwanese Dongshan Tea,” Energies 12, January 2019.

Advertisement