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Environmentally conscious consumers often ask me whether a real Christmas tree or an artificial one is the more sustainable choice. As a horticulture and forestry researcher, I know this question is also a concern for the Christmas tree industry, which is wary of losing market share to artificial trees.
And they have good reason: Of the 48.5 million Christmas trees Americans purchased in 2017, 45 percent were artificial, and that share is growing. Many factors can influence this choice, but the bottom line is that both real and artificial Christmas trees have negligible environmental impacts. Which option “wins” in terms of carbon footprint depends entirely on assumptions about how long consumers would keep an artificial tree versus how far they would drive each year to purchase a real tree.
From seedling to wood chipper
Many consumers believe real Christmas trees are harvested from wild forest stands and that this process contributes to deforestation. In fact, the vast majority of Christmas trees are grown on farms for that express purpose.
To estimate the total impact of something like a Christmas tree, researchers use a method called life cycle assessment to develop a “cradle to grave” accounting of inputs and outputs required to produce, use, and dispose of it. For natural Christmas trees, this covers everything from planting seedlings to harvesting the trees and disposing of them, including equipment use, fertilizer and pesticide applications, and water consumption for irrigation.
Life cycle assessments often will also estimate a system’s carbon footprint. Fuel use is the biggest source of greenhouse gas emissions in Christmas tree production. Using 1 gallon of gas or diesel to power a tractor or delivery truck releases 20 to 22 pounds (9 to 10 kilograms) of carbon dioxide into the atmosphere.
On the positive side, Christmas trees absorb and store carbon from the atmosphere as they grow, which helps to offset emissions from operations. Carbon represents about 50% of the dry weight of the wood in a tree at harvest. According to recent estimates, Christmas tree-sized conifers store roughly 20 pounds of carbon dioxide in their above-ground tissue and likely store similar amounts below ground in their roots.
However, using 1 gallon of gasoline produces about the same amount of carbon dioxide, so if a family drives 10 miles each way to get their real tree, they likely have already offset the carbon sequestered by the tree. Buying a tree closer to home or at a tree lot along your daily commute can reduce or eliminate this impact.
And natural trees have other impacts. In 2009, Scientific American specifically called out the Christmas tree industry for greenwashing, because growers’ press releases touted carbon uptake from Christmas tree plantations while ignoring pesticide use and carbon dioxide emissions from plantation management, harvesting, and shipping.
Is synthetic better?
Artificial trees have a different set of impacts. Although many people think shipping trees from factories in China takes a lot of energy, ocean shipping is actually very efficient. The largest energy use in artificial trees is in manufacturing.
Producing the polyvinyl chloride and metals that are used to make artificial trees generates greenhouse gas emissions and other pollutants. China is working to reduce pollution from its chemical industry, but this may drive up the prices of those materials and the goods made from them.
Moreover, to consider sustainability from a broader perspective, production of real Christmas trees supports local communities and economies in the United States, whereas purchasing artificial trees principally supports manufacturers in China.
Going head to head
Recently the American Christmas Tree Association, which represents artificial tree manufacturers, commissioned a life cycle assessment comparing real and artificial Christmas trees. The analysis considered environmental aspects of sustainability, but did not examine social or economic impacts.
The report concluded that the environmental “break-even” point between a real Christmas tree and an artificial tree was 4.7 years. In other words, consumers would need to keep artificial trees for five years to offset the environmental impact of purchasing a real tree each year.
One major shortcoming of this analysis was that it ignored the contribution of tree roots – which farmers typically leave in the ground after harvest – to soil carbon storage. This omission could have a significant impact on the break-even analysis, given that increasing soil organic matter by just 1% can sequester 11,600 pounds of carbon per acre.
Reuse or recycle your tree
Consumers can’t affect how farmers grow their live trees or how manufacturers produce artificial versions, but they can control what happens after Christmas to the trees they purchase. For artificial trees, that means reusing them as many times as possible. For natural trees, it means recycling them.
This is essential to optimize the carbon footprint of a real tree. Grinding used Christmas trees and using them for mulch returns organic matter to the soil, and can contribute to building soil carbon. Many public works departments across the United States routinely collect and chip used Christmas trees after the holidays. If local tree recycling is not available, trees can be chipped and added to compost piles. They also can be placed in backyards or ponds to provide bird or fish habitat.
In contrast, if a used tree is tossed into a bonfire, all of its carbon content is immediately returned to the air as carbon dioxide. This also applies to culled trees on tree farms. And if used trees are placed in landfills, their carbon content will ultimately return to atmosphere as methane because of the way materials buried in landfills break down. Methane is a greenhouse gas 21 times more potent than carbon dioxide over a century, so this is the most environmentally harmful way to dispose of a used tree.
All kinds of factors influence choices about Christmas trees, from fresh trees’ scent to family traditions, travel plans, and the desire to support farmers or buy locally. Regardless of your choice, the key to relieving environmental angst is planning to reuse or recycle your tree. Then you can focus on gifts to put under it.
Bert Cregg is a professor of horticulture and forestry at Michigan State University. This post originally appeared at The Conversation.
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7 Comments
Unfortunately, by using a real tree for Christmas you kill the tree.
Scott,
Yes. The same thing can be said for carrots and cabbage: When you harvest your crop, you end up killing the plant.
That is so true. However, unlike a tree you can't leave a carrot or a cabbage growing in the ground for 100 years while it cleans the air. Also, most people don't clean, cook and then leave the carrot or cabbage sitting on a plate in the middle of the dining room table for 2 weeks while you Ooh and Ahh at how beautiful it looks before throwing it out without eating it.
Scott,
I have friends and neighbors who are Christmas tree farmers. No logging is involved. This has nothing to do with forest land.
Trees are planted in abandoned pastures, and they are pruned annually and allowed to grow for 8 years. Then they are harvested and a new crop is planted.
Now, if you are concerned about logging practices, and where your 2x4s and 2x6s come from, we can talk about that. There are conscientious loggers and environmentally irresponsible loggers. But don't confuse the issue. Christmas tree farms have nothing to do with logging.
Martin, I'm not confused, but you seem to be. Your argument is that since the tree is planted to be a Christmas tree (pruned and "allowed" to grow) then it really isn't logging. I guess if a tree falls in a Christmas tree lot and nobodies there to hear it then it's not logging.........
But anyway, a tree cut down to become a 2x4 BECOMES something. It supports your roof, it builds your walls. It will stay there doing it's job for years, maybe decades as long as you maintain the building and keep water away from it. Heck, even after the building has outlived its usefulness you could still go in and salvage the 2x4.
Planting a tree and tending it carefully for 8 years and then killing it so it can stand drying out in your livingroom for two weeks covered in tinsel before getting tossed or mulched is wasteful and pointless. Why would you spend good money on a "product" that you'll throw away in 2 weeks when you could buy an artificial tree and reuse it every year for the rest of your life?
All I'm saying is if you cut down a tree then I hope you'll use it for more than just decoration.
Here's the point you seem to be missing. If the tree wasn't going to be cut down for use as a Christmas tree, it wouldn't be there at all. And it wouldn't get re-planted after each cutting. So from a carbon standpoint, it's at worst a neutral thing.
If your biggest concern is it being a waste of money, my question is why do you care? Lots of people spend orders of magnitude more money on much stupider things.
The idea of buying an artificial tree once and use it the rest of your life is great, and that may work for you. But if you think that's a viable model for the general population, you are dreaming. People throw out and re-buy artificial trees at about the same rate they do with any other consumer good. They get bored of what they have, they see something that looks better, etc. I would be very surprised if the average artificial tree lasts more than 5 uses.
The concept of reuse and repurposing of the tree took up about a quarter of the whole article.
Scott,
I understand your position. Clearly, you have no desire to buy a Christmas tree, because doing so makes no sense for you and your family. That's fine.
There are many forms of agriculture. Christmas tree farming is a little bit like growing flowers -- a huge crop in some areas. The crop is harvested and enjoyed -- but not eaten. Another comparison would be the growing of lavender and other aromatics for the production of perfume -- again, a crop that is harvested and enjoyed, but not eaten.
Deciding which types of agriculture make sense is complicated. From a global warming perspective, it makes sense to be a vegetarian. I'm not yet ready to rail against meat eaters, however, because diet is a personal decision. It's tricky to know which issue is the most important.
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