I wrote about live Christmas trees a couple weeks back and how to best care for them, but a conversation came up over Thanksgiving dinner that required me to do a little digging. It all had to do with the carbon footprint of a Christmas tree. Every December, millions of households face the same question whether to buy a real Christmas tree or pull the artificial one out of the garage? The debate rages on about that holiday scent, needle drop, or fire risk. Now added to the pile, carbon footprint. The answer is not as simple as “real = good, fake = bad” or vice versa. 

The true carbon footprint depends on sourcing distance, end-of-life disposal, and, most importantly, how many years an artificial tree is used. A typical cut Christmas tree (usually a fir, spruce, or pine) is grown on a dedicated tree farm for 7 to 12 years. During that time, it acts as a carbon sink and has a negative carbon footprint (negative being good in this case). A single 6-foot tree absorbs roughly 10 to 20 kg of CO₂ over its lifetime, depending on species and growing conditions. Modern Christmas tree farms are not converted forests, they are an agricultural crop like corn or wheat, often planted on land unsuitable for food production. After harvesting, the land is immediately replanted to provide for future years. A tree grown close to home adds almost nothing to its footprint, but one trucked 200 miles or more can add 5 to 10 kg CO₂e. CO₂e stands for carbon dioxide equivalent. 

In the United States, the average real tree travels about 100 to 150 miles, contributing roughly 3–5 kg CO₂e. Sorry to get so technical, but this is how they measure carbon dioxide. What it boils down to is if you are going to get a real tree, then get it as close to home as possible to mitigate carbon dioxide emissions from transportation. After you are done with your tree, how you dispose of it is also important. Mulching and composting your Christmas tree releases the least amount of carbon as most gets absorbed back into the soil. Burning your tree releases the most carbon back into the atmosphere.

So, what about artificial trees? Nearly all artificial trees are manufactured in China from petroleum-based PVC plastic, steel, and aluminum. A 2023 life-cycle assessment by the Carbon Trust estimated the embodied carbon of a typical 5 ½ to 6 foot artificial tree at 40 to 50 kg CO₂e for a basic model, and up to 80 kg CO₂e for a premium, pre-lit version with LED lights and metal bases. Those estimates include everything from the manufacturing to putting it up in your living room. Once the tree reaches your living room, its annual operating emissions are essentially zero (beyond the electricity used by lights). The tree is used for a few weeks and stored for the rest of the year to be used year after year. 

The amount of years that an artificial tree is used without being replaced is where the carbon footprint of an artificial tree can be lower than a real tree. Because the real tree’s impact is incurred every single year and the artificial tree’s impact is a one-time upfront cost, the environmental winner is determined by the number of seasons the artificial tree is reused. Regardless of the math, if you use an artificial tree for at least 10 years, your tree will have a smaller carbon footprint than 10 real trees.

But here's the rub, carbon dioxide isn't the real greenhouse gas we need to be worried about, even though that is what everyone is talking about. Sulphur hexafluoride is a synthetic gas that does not occur naturally in meaningful quantities. It is deliberately manufactured for industrial use because of its exceptional electrical-insulating and arc-quenching properties. Sulphur hexafluoride is used in and the manufacture of products like circuit breakers, semiconductors, particle accelerators and soundproof windows just to name a few. What makes Sulphur hexafluoride so bad is the fact that 1 kg of Sulphur hexafluoride released into the atmosphere is equal to 23,500 kg of carbon dioxide. Technology is working on replacing Sulphur hexafluoride, but that is a long term goal and while it is still being used and leaked into the atmosphere today, climate hawks want everyone to focus on carbon dioxide.