How people dispose of their Christmas trees after use is usually the single most important carbon consideration. The worst-case scenario happens when Christmas trees end up in landfill: the anaerobic conditions are conducive to the same carbon being released as methane – a greenhouse gas some 80 times more potent than carbon dioxide on a 20-year timescale. Whether or not a tree ends up in landfill has by far the largest impact on its carbon footprint: a tree that ends up in landfill emits some 4-5 times as much carbon as one that doesn’t, according to Carbon Trust figures.