The real emissions to avoid after Christmas aren't the ones produced by eating too many sprouts. Different methods of disposal for a Christmas tree can have a big impact on its footprint.
How you dispose of your real Christmas tree is much more significant than where it comes from and how much fuel was used to get it to your home. For a 2 metre tall real Christmas tree, with no roots, the carbon footprint is 16kg CO2e if it ends up in landfill. This is because the tree decomposes and produces methane gas, which is 25 times more potent as a greenhouse gas than carbon dioxide.
However if you burn your Christmas tree on the bonfire, plant it or have it chipped to spread on the garden, that significantly reduces the carbon footprint by up to 80% (around 3.5kg CO2e). Burning the tree emits the carbon dioxide that it stored up when it was growing so there's no net increase.
Real trees have much lower carbon footprints than artificial Christmas trees. The Carbon Trust estimates that a 2 metre artificial tree has a carbon footprint around 40kg CO2e, more than twice that of a real tree that ends its life in landfill, and more than ten times that of real trees that are burnt.
So if you have an artificial tree at home you would need to re-use it for at least 10 Christmases to keep its environmental impact lower than that of a real tree. Around two thirds of an average artificial Christmas tree's carbon footprint is from the plastic (mostly PVC film) that it is made from, which is produced from carbon intensive oil. Around a quarter of a typical artificial Christmas tree's carbon footprint is from the emissions produced when the tree is manufactured.
A real pine or fir tree naturally absorbs CO2 and releases oxygen. The best thing you can do at Christmas is keep a tree alive and breathing. Disposing of a tree by composting produces CO2 and methane. An artificial tree has a higher carbon footprint than a natural one because of the energy intensive production processes involved. By far the best option is a potted tree which, with care, can be replanted after the festive season and re-used year after year.
Darran Messem, Managing Director of Certification at the Carbon Trust
Contact your local authority to check if it has a scheme for chipping and composting trees to produce mulch/soil improver.