Did I Do the Right Thing by Cutting Down a Christmas Tree?

This question is almost as old as "paper or plastic?" and has provoked spirited debates between Christmas traditionalists and enviro-optimist believers in modernization and the Idea of Progress. Should we zealously shun the taking of a tree's life, even if it is purpose-grown at a locally owned Christmas tree farm, or is that in fact the better choice?

What is the impact of a fake tree?

According to the National Christmas Tree Association, 85% of fake Christmas trees are made in China and almost 10 million were sold worldwide in 2003. Let’s assume that the average fake tree weighs about 35 kilograms (kg), about 25 kg of that being the steel structure. The remaining weight consists of about 3 kg small molded plastic parts made from high-density polyethylene, and the "needles," which are made from polyethylene foil and also weighing about 2 kg.

Many trees come pre-strung with lights which consist of 2 kg of PVC, 2 kg of copper wire and 1 kg of glass bulbs (or plastic lenses in the case of LEDs). Using data from a life cycle assessment database I determined the amount of embodied CO2 emissions to be about 57 kilograms:

• Steel: 36.4 kg CO2
• Polyethylene: 7.4 CO2
• PVC: 1.8 kg CO2
• Copper: 10.9 kg CO2
• Glass: 0.58 kg CO2

Shipping the 35 kg "tree" from China (10,000 km), mostly by container ship, but also by truck, causes an additional 5-10 kg of CO2 emissions, depending on the destination, and picking it up from the store can add another 5-10 kg. So the estimated total CO2 emissions for the fake tree are over 70 kg. According to the National Christmas Tree Association 27 million real Christmas trees and 8.2 million fake tree were sold in 2010 but there are over 50 million fake trees in use. Greenhouse gas emissions from fake trees purchased this year total over 600,000 tons of CO2, that’s how much CO2 is absorbed by 300 square miles of forest.

Fake Christmas trees contain enough lead and other dangerous substances that they come with Proposition 65 warning labels in California. While this is dangerous enough for adults handling the trees as well as children and pets that may come into contact with them, the impact is even greater in China, where workers are paid around $100 per month to manufacture these trees.

What is the impact of a real tree?

One study found that a 5-foot Douglas fir Christmas tree contains 7 pounds of carbon (that’s the atom), which would turn into about 11.6 kg of CO2 (that’s the molecule) if it were to combust or decay completely. Because this carbon was originally removed from the air (sequestered), the real tree can be considered “carbon neutral” because it does not add more greenhouse gasses than it removes. In fact, during its growth, the tree will deposit some of that carbon in the soil where it will remain, making the growing of each tree a net carbon sink.

Christmas trees are grown on tree farms and not in actual forests. These tree farms sequester CO2 constantly, especially during the young trees' period of vigorous growth. Because they are grown for harvest, we are not actually decreasing the amount of CO2 sequestration capacity, but increasing it by making space for new trees to sequester greenhouse gasses. When you throw your tree to the curb after the holidays it is most likely taken to a composting facility where it is turned into soil. This takes the carbon that the tree sequestered from the atmosphere and stores it in the soil. Instead of kicking it to the curb you can compost it at your house and turn it into nutrients for your other plants, or you can consider a potted tree that you can plant after the holidays are over.

The production of Christmas trees creates domestic jobs and the minimal ground-application of fertilizers and biocides has much less of an impact than the production of their artificial counterparts. Real trees do not require any health warnings and they are fully biodegradable/compostable. In many locations the real trees are trucked in from hundreds of miles away, and like the artificial trees, you typically have to drive somewhere to get them. Even if we assume that the emissions from transporting both real and fake trees are about the same, and that they are covered in comparable strings of lights, the fake tree still has a larger impact than the real tree. This is because the fake tree causes a net increase of greenhouse gas emissions, while the real tree actually absorbs more CO2 than it returns to the atmosphere.

What's the bottom line? Real or fake?

The real tree is the clear winner from an environmental perspective. Of course, the fake tree only needs to be picked up from the store once so, for each year you keep the fake tree, the relative greenhouse gas emissions impact decreases. Depending on many variables, the fake tree could be even with the real tree in as little as two or three years, but that is without taking into consideration the fact that fake trees are made with non-renewable resources, in questionable working conditions, contain potentially harmful materials, and are not biodegradable nor easily recyclable.

If you choose a real tree this year, be sure to look for a locally owned Christmas tree farm that grows its trees on-site. Of course, if you're in a city, it's probably best to get your tree from a Christmas tree lot, even though it has been trucked in; otherwise you will have to drive out to the suburbs. If you're feeling creative and crafty you can create your own Christmas "tree" with materials that you would otherwise discard, like beer bottles or computer parts.

Copyright Treehugger 2011