Greenhouse, Carbon Dioxide & You

Let’s talk about you. You live in Australia. You consume energy, which pumps CO2 into the atmosphere. You’re part of the global warming problem. Feeling guilty yet?

How big a part of this problem is your driving? Passenger vehicles yield just 7.4 per cent of Australia’s CO2 emissions, and our national emissions are just 1.4 per cent of the world’s total. Crunch those numbers, and Australia’s cars total just over one one-thousandth of global CO2 emissions.

According to the Australian Bureau of Statistics Australia has 11 million passenger vehicles. So your car represents one one-thousandth of global emissions, divided by 11 million. Conclusion: Your car isn’t even a blip on the global warming radar.

The rest of this column is about why, despite the above, CO2 really should concern you. 


It doesn’t matter what you do as an individual – but it certainly does matter what we do collectively. Atmospheric CO2 levels are the highest they have been in the past 650,000 years, based Antarctic and Greenland ice core samples. They’ve jumped from 280 parts per million at the start of the 20th Century to 380 parts per million today. According to the UK Meteorological Office, the 10 warmest years on record have all been since 1990. The balance of credible scientific opinion says there’s a strong connection between these facts.

Scientific research sponsored by the UK, US and Australia, and endorsed by the Intergovernmental Panel on Climate Change (IPCC) ‘best guesses’ the absolute danger level of atmospheric CO2 at 400ppm – about 10 years away if current emissions trends continue. This would hike the planetary thermostat just 2 degrees C above the pre-industrial level. The report concluded that beyond this level, “risks of abrupt, accelerated or runaway climate change increase”.

Everyone in the know is worried. John Schellnhuber from the UK’s Tyndal Centre think tank put it like this: “If we go beyond two degrees we will raise hell.” Presumably, Old Testament-style.

‘Save the planet’ is a common theme of the green movement. It’s rubbish, however, because the planet will survive regardless. The truth is much more selfish: it’s humanity’s survival that’s at risk.


What worries researchers most is that nature is not manageable. If we liberate enough CO2, climate change could become irreversible. These so-called ‘amplifying feedbacks’ lead to ‘tipping points’ – points of no return.

It could happen like this: On the floor of the world’s deep oceans there is an estimated 10,000 billion tonnes of carbon locked within ice-like solids called methane hydrates. Water pressure and low temperature keeps the methane (natural gas) ‘down there’. Global warming heats the ocean, which could destabilise the methane hydrates, yielding all that methane into the air. Methane is many times more powerful than CO2 as a greenhouse gas. Result: climate change runs away, and John Schellnhuber’s hypothesis (above) is proved, to our considerable detriment.


Sticking with the IPCC’s best guesses, keeping within the two-degree global warming range means we can (maybe) ‘afford’ to liberate a maximum of 400 billion more tonnes of fossil-fuel carbon from oil, natural gas and coal. And ‘afford’ is a euphemism because we really are engaging in high-stakes gambling from here forward.

Optimistic assessments of conventional global oil reserves total 270 billion tonnes of carbon. Gas: carbon totalling 500 billion tonnes. Coal? A staggering 3500 billion tonnes of carbon.

What this means is that if we are to keep the planet out of the red zone, some oil will have to stay in the ground, along with most of the gas and nearly all of the coal.

Conclusion? Don’t worry about fossil fuels running out; we can’t afford to burn them until they do. The global energy economy needs to switch to renewables quickly, and in the meantime we all need to extract more bang from each kilo of liberated carbon.


Switching to renewables will take time. With hydrogen, for example, delivery infrastructure does not exist, and current engines will be obsolete. In the meantime, we need to consume less fossil fuel while conducting business as usual. We’re talking efficiency, which is not a new concept.

Becoming more efficient with fuel is not that hard. Most people could cut their fuel bills – and consequent CO2 emissions – by 10 per cent just by driving more carefully. Going with the flow in traffic, easing off earlier when traffic lights go red, and accelerating a little less aggressively will accomplish that. No capital investment is required.

In 2005, passenger vehicles in Australia consumed 18,144 million litres of fuel. If you mark out a square on the ground with 100-metre sides, you would need to extend it 1.8 kilometres into the air to fill it with that much fuel – and even then a few hundred thousand litres would be lost. Australia’s one-year fuel tank would dwarf the world’s biggest skyscrapers.

If we all drove more efficiently there would still be 180 metres of fuel – mostly carbon – left in the tank at the end of the year.

The Federal Government, derives a 38-cent excise (plus 10 per cent GST) on every one of those 18,144 million litres, and is also the country’s biggest advertiser – but all that lost revenue is hardly an incentive to launch a high-profile marketing campaign targeting fuel efficiency any time soon.

Next step on the road to more efficient motoring is simply using the old car a bit less – say five per cent less. Many could accomplish this just with a bit more planning – getting two things done for the price of one trip, instead of making two trips. National saving: another 90 metres of fuel in the big tank.

Should you upgrade to a better, more fuel-efficient car? That’s debatable. Almost every car company has jumped on the ‘green’ bandwagon, an incomprehensibly hypocritical step, given the business at hand. Around 5000kg of CO2 is emitted in the manufacture of a new car. Just to break even, in terms of carbon footprint, this amount of CO2 would need to be saved via lower fuel consumption, which depending on use could take several years.

Fuel efficiency per se isn’t a good enough reason to buy a new car, but if it is time for you to upgrade for other reasons, perhaps it should weigh heavily on your decision.

What the car industry should be doing, but isn’t, is investing in lightweight vehicle design, because putting a couple of hundred kilos of humanity in a vehicle that weighs two tonnes is fundamentally flawed from an efficiency perspective. What few gains have been made in lightweight vehicle design, via advanced computer modelling and clever use of high-strength steel alloys, plus composites and plastics, are negated by the fact that even small cars are getting bigger and heavier. Just compare the new Corolla to the first Camry, or the new Lancer to the first Magna.

Finally, it’s worth remembering that the average Australian’s carbon footprint has four times more to do with coal-fired electricity than petrol. Efficiency is about total energy use, not just cars.