What's greener? Planes, trains or automobiles

Transport is responsible for 44 per cent of New Zealand’s CO₂ emissions, 86 per cent of our oil consumption and around 16 per cent of our total greenhouse gas emissions – so thinking about our travel options can make a big impact on our environment.

After crunching the numbers, we found that when travelling the 635km trip between Auckland and Wellington, going by car is greenest – but only if you fill your vehicle with as many passengers as possible so the CO₂ produced can be shared by more people.

However, most cars on the road have only one or two passengers (the national average is 1.2 people per car), so if that sounds like you, then taking the train is your best option for the environment at only 36kg of CO₂ emitted per passenger. Unfortunately the journey will take a whopping 10-and-a-half hours!

If time is precious then flying will get you there in an hour, but it will also result in over four times the equivalent pollution for your journey.

Flying’s double-whammy

Short-haul flights, like the trip between Auckland and Wellington, tend to be worse for the environment than long haul flights as take-off and landing use more fuel. And another reason why flying is worse is that, while technically burning jet fuel will only release 75kg CO₂ per person for this flight (which is less than for a passenger in a car), burning fuel at high altitudes triggers reactions that have more harmful climate effects. This results in actual CO₂ levels of more than double the above figure.

For example those fluffy cloud-like streams that you see in the sky behind airplanes may look pretty but they are formed when the water vapour from burned jet fuel condenses at altitude. These contrails have been shown to stop heat from escaping the earth, which also contributes to global warming.

So taking the train may take the longest, but it is a simple way to reduce your carbon output, and lets you walk around and carry out other activities – or even just sit back and relax as you enjoy the scenery.

The verdict

Taking the train is the greenest option – so if time isn’t a constraint, sit back and enjoy the amazing scenery.

Have an eco dilemma that needs expert advice? Email [email protected] with ‘My dilemma’ in the subject line, or write to Green Ideas, PO Box 47177, Ponsonby, Auckland 1144.