What's the story with carbon offsetting?

Al Gore's film crusade aimed at exposing the myths and misconceptions surrounding global warming's relentless march opens in Ireland this week and it won't make for comfortable viewing. In An Inconvenient Truth, Gore says that the planet may be just a decade away from a point of no return, after which extreme weather, floods, droughts, epidemics and deadly heat waves will permanently take hold.

While the predictions are dire, the man who would have been president (and may be president yet) remains convinced that there is still time to make a difference. He says we cannot just continue sleepwalking towards catastrophe and if the planet as we know it is to survive, then changes at a governmental, corporate and personal level are absolutely essential.

One of Gore's key messages is the need for individuals to take responsibility for the amount of carbon dioxide they produce and to do something about it. It is, he says, not hard for consumers to make a difference and becoming carbon neutral doesn't have to cost the earth.

Leading by example, An Inconvenient Truth is the "first carbon-neutral documentary" ever made. Its producers calculated the film's "carbon footprint" by working out how much energy was used to make and promote it including "all travel-, office- and accommodations-related emissions". They then paid $12 (€9.30) for each tonne of CO2 that was produced. The money is to be used to help build Native American- and farmer-owned renewable energy projects.

It is a simple way of lessening the damage wreaked on the environment. A carbon footprint measures the amount of greenhouse gases produced by human activity in units of carbon dioxide - an average person in the developed world will generate in the region 6,800 kg (15,000 pounds) of carbon pollutants annually. To counter that, carbon offsetters can be paid to develop alternative energies or plant trees to remove carbon dioxide from the atmosphere.

The Foo Fighters, Coldplay and Radiohead have all offset tour emissions by protecting forests while Leonardo DiCaprio, Cameron Diaz and Brad Pitt among others have invested in trees as way of compensating for the oil their cars guzzle and the aviation fuel that is used in their globetrotting adventures.

Closer to home, some of Ireland's successful musicians are making efforts to lessen their own carbon footprint. "What we have done in the last year is to make our tours carbon neutral," says Brian Crosby from Bell X1. Through a site called www.carbonneutral.com, the band calculates the emissions from all the transport used while on tour and then they pay to plant the number of trees needed to offset that. It cost surprisingly little - the trees needed to clear the carbon from their most recent Irish tour cost not much more than €40, although Crosby points out there were very few flights involved. It is airline traffic that generates a vast amount of the CO2 that individuals are responsible for.

It isn't just bands and actors and one-time presidential hopefuls who are focusing attention on the need to become more carbon neutral. While it may sound like Montgomery Burns joining Greenpeace or Philip Morris sponsoring a lung cancer ward, British oil company BP last month unveiled a scheme aimed at helping drivers chart and then reduce their carbon dioxide emissions.

All ironies apart, under BP's initiative motorists will be able to calculate their annual CO2 emissions using the www.targetneutral.com website. An average car, driven 10,000 miles a year, will generate about four tons of CO2, enough to fill a medium-sized hot air balloon. To neutralise this amount of carbon emissions would cost about £20 (€30).

Critics say carbon neutrality is more about creating a feel-good factor than helping the environment. It can take a tree up to 100 years to capture 1,360 kg (3,000 pounds) of CO2 from the atmosphere - five trees would have to live for a century to take out all the CO2 generated by the average American in a year.

Many environmentalists quite reasonably point out that that the only real solution to climate change is for fossil-fuel burning to be stopped. This, they argue, will never happen if people and corporations believe it's okay to pollute as long as emissions are offset through a carbon neutral programme.

"Obviously people have to drive and have to fly and that's fine, but we should be more aware of the consequences of our actions," Brian Crosby says. "I'd like to see people booking flights online be shown information on the carbon emissions that will be produced by the flight and then have the option of paying a small sum of money to offset that."

He points out that an optional emissions tax would be no more than the airport taxes we currently take for granted. Crosby is not naive and accepts that carbon offsetting alone will not be enough to halt the environmental devastation predicted in An Inconvenient Truth. "Clearly carbon neutrality is not the solution to the problem but it is something positive that everyone can do," he says. "It is up to governments, particularly the US government, to do a lot more to tackle the climate change crisis. This is just a way for people who are concerned about the environment to make a difference, however small."

Carbon data to chew on

A return flight to Athens produces approximately 1 tonne of CO2, or roughly the same amount as driving a 1.4 litre car for three months.

The cost of offsetting the Athens flight through a tree-planting programme, via www.carbonneutral.com, is €4.35.

Heating, lighting and powering appliances in an average-sized three-bed detached house generates about 5.6 tonnes of CO2 a year.

Replacing a regular light bulb with a compact fluorescent light bulb uses 60 per cent less energy and will save about 136kgs of carbon dioxide a year.

Avoiding just 10 miles of driving every week eliminates about 227kgs of carbon dioxide emissions per person a year. And it's better for you.

Keep your car tuned and your tyres hard. Regular maintenance helps improve fuel efficiency and reduces emissions while properly inflated tyres should increase mileage by around 3 per cent.

By sticking on an extra jumper and turning the thermostat down two degrees in winter you could save about 0.9 tonnes of carbon dioxide a year.

A tree will absorb one tonne of CO2 in its lifespan.