I HAVE to admit that maths was far from being my strongest subject at school. Teachers would be literally tearing their hair at my failure to comprehend even the simplest equations. As I eventually stumbled my way to inglorious O-level failure, you will perhaps bear with me when I admit to being perplexed by the seeming mathematical complexities of personal carbon footprints.
Fearlessly, I recently completed one of the profusion of carbon footprint calculators that you can now find on the internet. Embarrassingly, it revealed that my personal carbon footprint is just above average for a UK citizen. (Significantly, I feel, according to the carbon footprint calculator, if I were to give up the car, not use, public transport, walk everywhere and live in an abode with no heating or electricity from fossil fuels, I could still only cut my carbon footprint by around 50%)

But what to do? My largest CO2 contribution comes from private car mileage. Now public transport is virtually non-existent around here, so perhaps I should look at one of those petrol/electric hybrids like the Toyota Pious, or whatever its name is.

According to official figures, this car has a CO2 figure of just 104g/km as against the 143g/km produced by my diesel-guzzling hatchback. Hang on a minute though, recent research in the US suggests that the choice is not so clear cut. Critics claim that the environmental costs of cars should be measured from raw material to the scrap-yard. This dust-to-dust calculation is said to reveal that a fuel-efficient modern car can be bad news if it has to be shipped halfway round the world, is built from large numbers of complex components, and uses highly refined and processed materials. Based on these figures, the US researchers claimed that the American-made 4-litre Jeep Wrangler 4x4, built to an old-fashioned design and slack tolerances, using low-grade materials and with a CO2 figure three times that of the Prius, is actually the greenest car Americans can buy.

So confusing maths there. In fairness, the Prius is the first attempt at a hybrid car and the technology when perfected further will bring even greater efficiencies.

Perhaps I could offset my carbon footprint by planting a tree instead? Everyone’s at it these days, particularly our politicians who presumably need to assuage the guilt of owning multiple properties and flying round the world on seemingly pointless fact-finding missions. (Of course, most environmental legislation comes from Europe – where the ludicrous decision to have two parliaments leads to thousands of officials creating an estimated 20,000 tons of CO2 per year on completely unnecessary journeys between Strasbourg and Brussels.)

Each tree planted is said to offset your environmental impact by ‘breathing’ in about 730kg of CO2 over its lifetime of 100 years. It is estimated that the average person needs to save about 7,000 kg of CO2 per year, so it figures that planting ten trees per year is one way of achieving this.  

Hang on a minute! If each UK resident were to plant ten trees per year we would be looking at 6 billion new trees come 2017 – that’s one tree for every person in the world (impressed with my maths, huh?). And where are we going to put all these trees? Simple, force them on the third world countries who have been desperately clearing their forests to eke out the kind of hand-to-mouth existence which we left behind around 100 years ago.

But even planting trees, it seems, may have a detrimental environmental effect. A recent report in Science magazine looked at the drastic effect that tree plantations have on stream flow. A study by a team from a North Carolina university compared planted areas with plots nearby that did not have trees. By sucking water out of the ground and evaporating it from their leaves it was found that the trees reduced water flow by half. And 13% of streams dried up for at least a year. This would have effects downstream where less water would be available for plants and animals. Nutrients in the soil were also leached out by tree planting which affected biodiversity.

Of course, the other reason we can’t plant all the trees here is that John Prescott needs a lot of the spare land for housebuilding for our expanding population.

Which brings us to the problem of sustainability. A number of studies have suggested that the current population of the Earth, already over six billion, is too many people to support sustainably at current material consumption levels. Taking the current world growth rate of 1.4%/year, it is estimated that in 722 years there will be one person for every square metre of land on earth – which presumably he/she will have to share with his tree.

Actually, that’s one thing that the carbon footprint calculators don’t take into account – offspring. By not having children I have actually reduced my carbon footprint for future generations. On average in the UK, each person is said to produce around 11,000kg CO2 per year. So based on just one child living for 75 years, I will have saved a total of 825,000kg of CO2. While I’m on a mathematical roll, if I were to have two children, and each of those children were to have two children, etc, etc, during the 722 years mentioned earlier, there would have been over 134 million of my offspring (more than twice the current population of the UK, all carrying my genes – how scary is that?), each contributing 11,000kg of CO2 per year. According to my admittedly dodgy maths, this means that by not having children I will have saved the environment (presuming each descendant lives for 75 years) 110,715,000,000,000kg of CO2.

Smug? Actually, yes, and not just for my mathematical prowess. Although, I am not seeking inclusion in the Queen’s birthday honour’s list for my services to the environment, I feel my restraint in the trouser department should at least be acknowledged by the population at large.

Neil Everitt

Editor