It's a splendidly disastrous sound, when a stately lord of the plant kingdom bites the dust.
OK, no, I don't mean this literally of course; I've never committed first-degree arboreal murder. But I do drive a car, which means I've been pumping out roughly* five to six metric tonnes of carbon dioxide every year since I got my licence. A fully-grown tree, over the course of its life-time, sequesters, or absorbs, roughly* 1 tonne of atmospheric CO2.
So it's most appealing to think I can green my carbon-blackened soul by giving a grove of hopeful young saplings a start in life.
The first week of September is Arbor Week in South Africa, and gleeful treehuggers are planting all over the place. Local politicians and dignitaries especially seem to have swopped human baby kissing for tree baby planting as the favoured PR vehicle. Not only are they potent symbols of natural regeneration, trees are extraordinary, intricate machines that sop up CO2 simply by being. Tamping down the soil round new roots is a noble, humble act against deforestation and climate change that we can all understand.
Well, on the face of it. As with anything to do with natural systems – and this is a serious reason why people get weary and throw up their hands at environmental issues – it’s just not so simple.
Some of the basic spoilsport arguments against tree planting as a way to offset carbon emissions go like this:
Trees can’t save us. It is far, far more effective to keep the carbon tucked away unmolested in fossil fuels underground in the first place, than to release it, as we do, like an evil genie into the atmosphere. Unless someone finds, and quickly, a magic lamp and a way to stuff the genie back in, the only real hope we have of curbing climate change is radical emissions reduction. Planting trees is something, but not enough, not nearly. It is naïve, and dangerous, to think we can expunge our environmental sins this way.
Trees die. And when they do, whether by chainsaw, fire or disease, they release their stored carbon back into the atmosphere. Planting a tree to fight atmospheric carbon is only really meaningful if the tree endures long enough. To successfully store that carbon, you need your tree to reach maturity, and this is hard to guarantee.
- Trees' net contribution to global cooling is pretty much impossible to quantify accurately. There are numerous throw-up-one's-hands-inducing controversies and complications with regards to this. For example, trees cool the planet down by absorbing CO2 and producing water vapour, but they may also have a warming effect because darker leaves tend to reflect sunlight less well than lighter surface areas. And reforestation itself might disturb and release carbon held in the soil.
But tree-planting is nonetheless not quite as futile an exercise as some of its detractors would have us believe.
If you are going to plant something, a tree is a good bet: they store carbon better than other botanicals. They have a host of other environmental benefits let's not forget – they help keep the air moist, as mentioned above, filter out city pollution, anchor soil and provide habitats for birds, insects and small mammals.
And, come on, trees are also just awfully nice. They make shade, and fruit, and natural jungle gyms, and they have great presence and personality. You can have a relationship with a tree in a way you can’t with a putting green or a herbaceous border. Ecotherapists tell us that simply gazing at one is soothing; even prisoners tend to be better behaved when the view from cell windows contains waving leafy branches.
Planting trees is also a wholesome activity. You can pay a reputable organisation to do this for you, but there’s much to be said for getting down and dirty with a spade yourself. It's good outdoor exercise and helps reconnect with the elemental – a process many of us comfortably numb privileged urbanites need in regular doses.
As long as you make a savvy choice of tree – indigenous, locale-appropriate and low-maintenance – and you plant it knowing full well it's not enough to save the world or buy environmental redemption, then no one's allowed to scoff at you.
Happy Arbor Week. It's not stupid.
- Olivia Rose-Innes, EnviroHealth Editor, Health24, September 2011.
*Very roughly estimated indeed. There are multiple factors that affect how much CO2 a vehicle produces (size, distance driven etc.), and how much CO2 a tree absorbs (species, location, longevity etc.) The estimates here are for a smallish petrol-fuelled vehicle doing about 10 000km a year, and a tree that's lived a long time, probably in the tropics, and done a pretty excellent sequestration job. My primary sources for these figures are the Intergovernmental Panel on Climate Change, the Environmental Protection Agency, and Trees for the Future.