A UK Royal Commission study conducted by York University calls air transport “the most heavily polluting form of transport on Earth”.
Yet, in terms of fuel consumption, air travel is not inefficient. According to figures from Landcare Research, each passenger’s share of the carbon dioxide emissions on an average domestic flight in New Zealand is 180g per kilometre, which is quite good compared to a two-litre car with just one passenger, which emits 370g per kilometre.
On the other hand, if you choose an average-sized diesel car and pile in the whole whanau, that’s only a modest 35g per kilometre.
One person’s share of the carbon dioxide emitted in a round trip to London is 5062kg. You’d have to drive more than 20,000km (by yourself) in a two-litre car to match that on the road.
So why do the New Zealand transport emissions statistics show that motor vehicles are responsible for 92% of carbon dioxide emissions but air travel is 3%?
This is because most countries don’t include international flights in their statistics. Air New Zealand environment manager Martin Fryer says, “The reason international flight data is not included in state carbon-emission statistics is that, under Kyoto, international aviation is exempt until 2012. To try to include aviation was seen as extremely complex.”
Although it gets the most attention, carbon dioxide is just one of several greenhouse gases. The other bits coming out of the back end of a Boeing include nitrogen oxides, sulphate, soot and water vapour.
Richard McKenzie, an atmospheric scientist at the National Institute of Water and Atmospheric Research (NIWA), began looking at the atmospheric effects of aeroplane emissions in the 1980s, when a study was commissioned to explore the potential effects of a new supersonic aircraft. This research helped scientists to better understand the complex chemical reactions that happen in the flightpath.
Most jets fly in the upper troposphere (between 10-13km up) where the thinner atmosphere makes their path more efficient. In this cold, clear air, the water vapour from jet engines forms into ice crystals. These vapour trails trap heat and warm the Earth’s surface. At the same time, the nitrogen oxides are interacting with ozone. The chemical reactions taking place increase ozone production. This extra ozone in the the troposphere is actually a greenhouse gas that traps heat. McKenzie believes that jet engines contribute more to global warming than a simple carbon dioxide calculation reveals.
In a 1999 special report, “Aviation and the Global Atmosphere”, the Intergovernmental Panel on Climate Change says the overall warming effect of aviation is 2.7 times greater than the effect of its carbon dioxide emissions alone. New research from the UK indicates that aviation will account for 5% of the world’s CO2 emissions by 2050. But the percentage that flying contributes to global warming may be much higher.
There is some good news. Improved aircraft engine design has resulted in a 70% decrease in carbon emissions from 1976 levels. Nitrogen oxide emission is forecast to fall by 80% by 2030. But fuel and pollution savings are being eclipsed as almost half a million new passengers take to the skies every year and another 13,500 heavy jetliners are scheduled to enter service by 2017.
Gore buys carbon credits to offset his flights. Using websites like www.carbonzero.co.nz, anyone can do this. (These credits go towards New Zealand native forest regeneration projects administered under the EBEX21 project.)
Planting trees is a good thing, McKenzie says, but not a true solution. “Planting trees is really only a stopgap solution. Eventually the trees die and then they release their carbon back to the atmosphere.”
Jet emissions linger in the stratosphere, modifying Earth’s atmosphere for about 100 times longer than when released near the ground. The carbon calculators don’t take this into account. Plus, it’s hard for trees on the ground to absorb carbon 13km up.
The only sure way to reduce the global warming contribution caused by aeroplanes is to stop flying.
There are other good reasons to avoid jet travel. Airports are a toxic source of noise and chemical pollution for people who live nearby. Every four hours, passengers on high-altitude flights are exposed to radiation equivalent to one chest x-ray.
Gore’s impact in raising awareness of climate change may justify his jet-setting contribution to the issue, but the rest of us are faced with a moral dilemma. It’s summed up with a concept that Guardian columnist, and author of Heat: How to Stop the Planet Burning (published by Allen Lane), George Monbiot calls “love miles”, or the distance between you and the people you love.
“If your sister-in-law is getting married in Buenos Aires,” he writes in Heat, “it is both immoral to travel there – because of climate change – and immoral not to, because of the offence it causes. In that decision we find two valid moral codes in irreconcilable antagonism. Who could be surprised to discover that ‘ethical’ people are in denial about the impacts of flying?”
Monbiot admits that his environmental consciousness has been shaped by travel abroad and says this partly explains the gap between good intentions and damaging actions. “While it is easy for us to pour scorn on the drivers of sports utility vehicles, whose politics generally differ from ours, it is harder to contemplate a world in which our own freedoms are curtailed, especially the freedoms which shaped us.”
But he concludes: “If you fly, you destroy other people’s lives.”
In the UK, where a Ryanair flight from London to Rome can be just 50p, some conscientious travellers are vowing to give up the air-travel habit. Websites like FlightPledge.org.uk encourage citizens to swear off it.
In January, Mark Ellingham, founder of travel-publishing company Rough Guides, announced that he would fly less and vacation in Britain. He is spreading a new message: travel less and stay longer.
“We have all mastered the art of beginning and ending a narrative at the points which suit us,” says Monbiot. Unless the story can be rewritten, a happy ending to the climate crisis will require us to fly less. The end of cheap oil could make the choice easy. Or Richard Branson, and his $3 billion commitment to developing alternative energy sources, will find a sustainable option.
In the meantime, maybe New Zealand should focus on its sailing industry instead of brokering its clear skies to bring an international aircraft test facility to Christchurch. Climate change wasn’t a factor in the decision to keep the Overlander running, but maybe it will be. A University of York report found that if journeys of less than 400 miles are undertaken by train rather than plane, 45% of all flights could be eliminated.
Air New Zealand ads say, “being there is everything”, but organisations like NIWA are trying to replace some flights with videoconferencing.
This could be the most inconvenient truth of them all. I don’t blame Gore for leaving it out.
From the Listener magazine:http://www.listener.co.nz/issue/3470/features/7452/the_inconvenient_truth_about_airline_travel,1.html;jsessionid=AA3386B23A3C97BDD178EAC53759EBBA