Which are greener, real or artificial Christmas trees?

Choosing between a real tree and an artificial tree for Christmas can be a conundrum. Which is better? There are some good-looking synthetic trees on the market. They last longer than the real variety, but they come without festive aroma and arguably authenticity.

This year the Irish Christmas Tree Growers Association have introduced the label Love a Real Tree, highlighting the green credentials of buying the real thing. But are they better for the environment? The answer seems obvious, but science is about putting a hypothesis or belief to the test. In such cases, scientists use “life-cycle analysis”, or LCA, a sort of bookkeeping approach that tots up the pluses and minuses of a product’s impact on the environment.

Christmas trees and their artificial cousins have been put through the LCA mill. The impact of trees grown locally in Canada was compared to imported artificial trees. The results are perhaps surprising. The real tree won out, but it is not a done deal: a consumer can easily tilt the balance either way.

Let’s take natural trees. In terms of climate change, the main negative of a real tree is how far a consumer drives to get it. The study counts on a round trip of 10km; impact on climate change trebled and vaulted that of a fake tree if you drove 32km just to get your tree.

“This is typical of an LCA assessment, where it really boils down to tiny differences making a big impact, things like transportation and end use,” says Dr Jean O’Dwyer at the University of Limerick, who is studying the effect of reusing wood on carbon balance. “It’s an evaluation of environmental impacts and can cover CO2, but also water, energy, land use, resources.”

She describes analysis of the Prius car as a good example. “When you do an LCA and taken into account how a Toyota Prius is made – so production, not just use – it is less sustainable than a standard car,” she says.

Each conifer sucks up over a ton of CO2 a year, more than oak, so is good for global warming. But it must be replaced once harvested (true on most Christmas tree farms). “When you cut down trees, you can regrow them and then there is a balance between carbon taken out of the forest and put back in,” says O’Dwyer.

Post-Christmas blues

And what you do with it in the New Year matters. Trees brought to local authority depots can be turned into mulch for parks, putting carbon into the soil, but their green credentials get axed if you chuck them into landfill. Buried wood generates methane, a more potent greenhouse than CO2. If you plan to drive far to collect your tree and landfill it after use, an artificial tree would be better in terms of global warming.

Artificial trees scored less well in the analysis because they are made of plastics and metals and are rarely recycled. They usually end up in landfill. The Canadian study found that 85 per cent of the climate change impact came from their manufacture and 8 per cent from transport from China to Montreal. Also, it matters where they are made.

“China has a high reliance on coal, so if made there carbon emissions shoot up,” O’Dwyers says.

Dr Fionnuala Murphy at the school of biosystems and food processing in UCD agrees: the electricity used to make the artificial Christmas trees is very important and varies country by country. “If certain [Scandinavian] countries made these trees, those with lots of renewables, that would bring the emissions way down.”

Still, you must also ask yourself how long you will keep your artificial tree. The Canadian study assumed six years. The longer you keep it, the lower its environmental impact. “The study found that if you kept your artificial tree for 20 years, it would be equal to using a natural tree every year,” says Murphy, who has assessed palm kernel shells for solid fuel – they were not as green as we thought.

Ultimately, LCAs rely on huge databases giving information, for example, on how much fuel a chainsaw uses or how much electricity and materials it takes to make plastic. “The big advantage of LCAs is that they conform to international standards, so research should be comparable,” says O’Dwyer.

The analysis, though, does not account for economic or social impact. Buying a fake tree for €100 and keeping it 10 years will save money compared with buying a real tree every year for €40. “That is a cost that could be important to some people,” says O’Dwyer. “But if everyone turned to fake trees tomorrow, you would affect the livelihoods here of those who depend on the tree market at Christmas.” The industry is worth around €21 million to the Irish economy.

Finally, the study tells us not to lose sleep over our tree choice from a climate change point of view: “The impacts on the environment are negligible compared to other activities, such as car use.” Car sharing or cycling to work one to three weeks a year would offset carbon emissions for either option.

IRELAND’S FAVOURITE CHRISTMAS TREE

Importing Christmas trees renders them far less environmentally friendly, but Ireland grows plenty of its own. Between 350,000 and 400,000 trees will be sold in Ireland this year, the Irish Christmas Tree Growers Association estimates. Half of the trees come from Wicklow and Wexford.

In Wicklow, Christy Kavanagh runs a Christmas tree farm, selling on site and at Leopardstown Racecourse. He explains that back in the 1980s, the Norway spruce was most popular but tended to shed needles: “It’s a great tree for outdoor display.”

There was a shift to Noble firs, which keep their needles and are a strong tree that can carry heavier decorations. “It is dark green, more layered and open,” says Kavanagh.

The most popular tree now, which Kavanagh also grows, is the Nordmann fir, a triangular tree with rich green foliage and soft needles. It is easier to grow and makes up three-quarters of all trees sold here.

[ lovearealtree.ie ]