(part of our guide to yuletide eco gifts, seasonal food and decorations)
Chopping down thousands upon thousands of purpose-grown trees and dragging them into our houses for a few weeks of the year, only to then drag them back out again and send them off for disposal by the council…this has got to be so much worse for the environment than buying one artificial (albeit largely plastic) tree and keeping it for….well, for ever, yes?
The only way to make a genuinely quantitative decision is to conduct a Life Cycle Analysis (LCA) of an artifical tree and compare it with an LCA of a natural tree, extending the comparison over a number of years.
Of course, the most obvious environmental difference is the fact of a one-off product vs an ongoing annual purchase — one would assume that the much larger environmental impacts at the production stage for the artifical tree would, surely, given enough time, eventually be offset by endless annual cycles of growing-transporting- disposing of natural trees.
Thus the question seems to boil down to: How many years would you have to keep your artificial tree before not buying that natural tree each year has cancelled out the environmental impacts of production? i.e. after how many years do you ‘break even’?
One 2011 study commissioned by the American Christmas Tree Association, the ISO-compliant PE America’s Comparative Life Cycle Assessment of an Artifical Christmas Tree and a Natural Christmas Tree,concluded that within only four years the Global Warming Potential (GWP) of the artifical tree breaks even with the real tree - if the natural trees are either incinerated or composted after use.
However, many assumptions are made - as they almost always have to be - regarding the details of both natural and artificial tree production, transportation and end-of-life disposal method. For example, the PE America study assessment of natural trees includes the environmental impacts of a human-made stand, and also assumes the Christmas tree farms use fertilisers and pesticides - and that the consumer drives at least 5km each year to pick up their tree in an average American car. Clearly not all of these assumptions will be applicable in the UK in 2014.
Now check this out: If the natural tree is landfilled (yes, landfilled) the Global Warming Potential break-even point will never arrive! That’s right - it will always be better for climate change if you buy the real tree - so long as you dump it in a landfill site!
Why? Because, at least for 100 years, and possibly for much longer, 77% of the carbon content of the tree will not escape into the atmosphere as greenhouse gas, but will remain trapped inside the sealed lining of the site. In this study based in the USA, landfill sites also convert a percentage of the greenhouse gases that the garbage releases into electricity, i.e. energy-from-waste - further reducing the GWP of a real tree sent to landfill. So if we took our cue from this, we’d all go out and buy natural trees and then insist on them being landfilled - except of course that that is now illegal in Europe.
This is the trouble with examining an isolated environmental impact and looking at it as a stand-alone issue within certain scope boundaries: because the dead tree in a sealed landfill site is not going to emit 77% of its carbon content into the atmosphere, that carbon sequestered during it’s growth has actually been removed from the air. Until, that is, the landfill site leaks or is uncovered or dug up or blown apart by a tornado…
Clearly, landfilling is not an option in Europe, which leaves incineration or composting, of which composting is the least harmful to the environment. In the PE study, however, the authors found that 50% of the carbon content of the tree is released back into the environment during composting due to degradation of the biomass (assuming that there is no energy credit for composting),and the overall life cycle of the composted natural tree therefore contributes to global warming. According to the PE LCA, after 5 years the composted natural tree is worse for climate change than the artificial tree.
Life Cycle Analysis usually assesses a range of different environmental impacts, including
primary energy demand - using energy from non-renewable sources
acidification potential - like acid raid, which causes forest die-back
eutrophication - overloading water with mineral nutrients causing deoxidification of water and fish die-back, and increased nitrogen levels in groundwater — i.e. drinking water
smog potential emissions of noxious gases contributing to tropospheric ozone concentrations
in addition to Global Warming Potential. Other impacts areas can include aspects of human health, other ecosystem quality effects and impacts on natural resources.
However, in the case of both real and fake Christmas trees, acidification potential and eutrophication are generally very low when compared with many other every day human activities or consumer products (such as driving a car or buying a television).
The natural tree even acts as a eutrophication ‘sink’ if it is composted - which means it absorbs more nitrogen during growth than is deposited to air or soil during its whole lifetime, including during end-of-life composting and transportation. It is therefore (albeit in an extremely small way) beneficial to natural water quality to grow, chop down and compost a Christmas tree.
An LCA study by Canadian consultants ellipsos found that the GWP break-even point for natural vs artificial trees is much further down the line - 20 years on - shown on the chart as the point where the two lines intersect.
This means that if you want your artificial tree to match natural trees for kindness to climate change, you need to hang on to it for at least 20 years.
The differences between the two studies can be attributed to different assumptions about transportation distances, cultivation methods, end-of-life methods and and scopes and boundaries, but both studies assumed the artificial tree is manufactured in and transported from China.
The one significant difference between the two studies is that ellipsos assumes incineration with energy-from-waste for end-of-life, since this is what actually happens to Christmas trees where the study was conducted in Montreal.
So the answer to the question - shall I buy another ‘real’ tree or go fake?
but reduce your tree’s footprint by:
carrying the locally-bought tree home on your back (preferably in an elf costume like I did this year….)
keep your stand for as long as possible, or prop your tree up in a bucket filled with bricks like my dad used to (!)
turn the lights off when you go out / go to bed
chop it up and use it on your (legal) log-burning stove instead of having the heating on for DIY energy-from-waste, or get it composted by your local council (most of whom will now have a special collection of trees from outside your house)
To put things into perspective, the emitted CO2 over the entire life cycle are approximately 3.1 kg CO2 per year for the natural tree and 8.1 kg CO2 per year for the artificial tree (48.3 kg for its entire life span). These CO2 emissions roughly correspond to driving an average car (150 g/km) 125 km and 322 km, respectively.
Therefore, to offset your Christmas tree emissions, ditch your car for;
one week per year for the natural tree
three weeks per year for the fake tree
OR, even BETTER
To be super-green,
buy a tree in a pot (make sure it’s pot-grown, not chopped-and-potted as it’ll die) and bring it in out of the garden / front yard each year
RENT a tree (yes, really!) from Muddy Boots from as little as £19.95 per annum and see how much bigger it’s grown each year -!
Check out our favourite tree - made from re-cycled-cycles…
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