Philadelphia - Natural Christmas trees outsell artificial trees each year by the millions. Many buyers of real trees believe that the firs, pines, and spruces they lash to their cars are more environmentally friendly.
But artificial trees are gaining in popularity, raising the question: Are real trees really better for the environment? Assessing the environmental impact is trickier than it seems.
Scientists, engineers, and industry consultants have dug deep into the data over the years, looking at just about everything from how natural trees are grown to how much water, fertilizer and pesticides are used in their growth, and how they are disposed of after Christmas.
For artificial trees, researchers look at the PVC and steel used to make them, their long transportation to the United States from China, the type of stand used, and how many years the trees are reused.
Here are some factors to consider for each type of tree, according to a 2018 report by WAP Sustainability Consulting.
It takes time to grow a tree of about 6.5 feet _ the size used for comparison in the report. In all, it can take up to a decade to produce a Christmas tree from seed to sale. And the cut trees require a lot of transportation.
Consider that Oregon and North Carolina are the largest producers of Christmas trees, though Pennsylvania is fourth, according to the National Christmas Tree Association. So most Christmas trees travel long distances, which requires burning fossil fuels like gasoline and diesel that release carbon dioxide into the atmosphere. Carbon dioxide is the chief greenhouse gas that scientists say causes climate change.
Trees also need water to grow, and to prolong their life when they are placed in a home or building.
Further, natural trees are typically fertilized with nitrogen and phosphate. Most are protected by fungicides and herbicides, such as glysophate, the main active ingredient in the Roundup brand of weed killer. Herbicides can contaminate groundwater, surface water, and soil.
Finally, a tree's disposal plays a significant role in its environmental impact. Real trees have to be disposed of each year. Transporting a tree to a landfill uses gas, and its placement in a landfill also causes methane emissions (which some landfills capture to generate electricity). The trees also release carbon dioxide as they break down in the landfill.
Trees are often incinerated, a process that can release more carbon dioxide, but also helps generate electricity depending on the type of facility.
Trees can also be composted, a process that while environmentally friendly also gives off carbon and methane.
Manufacturing an artificial tree is an intensive process that involves using polyvinyl chloride (PVC), a white powder plastic resin, and steel to build the branches, tree pole, and other parts. PVC, much like other plastics, is derived from fossil fuels.
Trees are also packed in corrugated cardboard boxes and possibly wrapped in plastic.
Mostly made and assembled in China, the trees begin an even longer, more fuel intensive journey than their natural counterparts. Trucks take the trees from plants to ports. The trees are loaded onto container ships bound for U.S. and other ports. Then, once again, they are loaded on trucks destined for retailers. Finally, they are driven home by customers.
In all, an artificial tree can travel 13,000 miles from production to the stand in a customer's home, according to the WAP Sustainability report. That's more than half the Earth's 24,901-mile circumference.
When an artificial tree is tossed curbside, it likely ends up in a landfill, where it will last decades. Likewise, its cardboard packaging can end up in a landfill or be recycled.
Weighing all those factors, a natural tree would be better for the environment if a homeowner planned to use an artificial tree for only a short time.
A homeowner would have to use an artificial tree for about five Christmases (the WAP report calculated the longevity at 4.7 years) for it to have less of an impact on the environment than a real tree.
Others have come up with similar findings. A 2018 report by Dovetail Partners determined that "when a full range of environmental impact indicators, beyond global warming potential alone, is considered, results indicate that an artificial tree must be kept in service at least four to six years in order to achieve comparable environmental impact to a yearly series of natural trees."
So if you're going to buy an artificial tree, plan to use it a long time or consider buying a used one online or from a thrift store, or donating when you're done with it. If you're buying a real tree, consider a potted tree that can be replanted, mulching or composting a cut tree, or donating it to groups that use trees for restoration projects.