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Dear Pablo: Which is greener a fake Christmas tree or a farm raised tree?
Yes, they seem tacky and don't make your house smell like a coniferous forest but they also won't dry up and shed their needles all over the place before spontaneously combusting. Also, if you cut down a tree in the forest aren't you are taking away its ability to sequester carbon for many years to come? So, from the perspective of a world that already has more carbon dioxide than can take, which is better, a cut tree or a fake one?
How Bad Is The Fake Tree?Let's start with the fake tree. I pick a model that is made in China (and it seems that most of them are), and weighs about 35 kg (77 lbs). The frame is made from steel and weighs about 25 kg. The remaining weight consists of small plastic parts made from high-density polyethylene, weighing about 3 kg, the "needles," made from polyethylene foil and also weighing about 2 kg, and the pre-strung Christmas lights which consist of 2 kg of PVC, 2 kg of copper wire, and 1 kg of glass bulbs. Using data from a life cycle analysis database I can determine that the amount of embodied CO2 emissions.
- Steel: 36.4 kg CO2
- Polyethylene: 7.4 kg 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. So the estimated total CO2 emissions for the fake tree are over 62 kg. According to the National Christmas Tree Association in the year 2000 there were 32 million real Christmas trees 50.6 million artificial trees in use. In 2001 the annual sales of fake trees was 9.6 million. So if we assume that the fake tree sales have remained steady the greenhouse gas emissions from fake trees purchased this year total almost 600,000 tons of CO2, the amount of greenhouse gas credits that Pacific Gas & Electric (PG&E;) recently purchased on behalf of its ClimateSmart customers.
Compare That To A Real TreeNext we will find out how many years you would have to own this tree to justify the emissions from production compared to the CO2 removed from the atmosphere (sequestered) by live trees. It turns out that trees sequester somewhere around 172 kg (36-342 kg) of CO2 per year. This would indicate that it is more environmentally friendly to buy a fake Christmas tree once, at a CO2 cost of 62 kg, than to cut down a tree every year at a CO2 cost of 172 kg (annual, for the projected life of the tree), the amount of CO2 not sequestered by the tree because it is now dead.But most 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. Since 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.
Are There Any Other Options?One popular and sustainable option is getting a potted, live Christmas tree. If you keep it properly watered it will not dry out, shed, and become a fire hazard. It will also continue to provide that pine-fresh scent throughout the holidays. But the best reason is that when you are done with the tree, you don't need to kick it to the curb like your neighbors, but can plant it outside where it will sequester CO2 for many years to come.Pablo Päster is a weekly columnist for TreeHugger.com, an experienced greenhouse gas engineer and the Senior Environmental Program Manager at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
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