Planes, trains, automobiles: reducing our carbon footprints

Aeroplane contrails in the sky
If politicians really want to address the impact of air travel, why not consider a simple measure like not allowing more airports or airport extensions to be built?
Dr Jens Borken-Kleefeld
A study from climate researchers in Austria and Norway has provided better estimates for the effects of personal travel choices on the environment…

The paper, which has appeared in the journal Environmental Science & Technology, demonstrates that, while air travel still has the largest climate impact per distance travelled, the individual transport choices we make when taking business trips or going on holiday can make a significant difference, particularly over distances of 500-1000 kilometres.

Dr Jens Borken-Kleefeld, a research scholar on the Mitigation of Air Pollution and Greenhouse Gases programme at the International Institute for Applied Systems Analysis (IIASA) in Austria, conducted the research along with Jan Fuglestvedt and Terje Berntsen from the Center for International Climate and Environmental Research (CICERO) in Oslo, Norway.

In an interview with, Dr Borken-Kleefeld outlined the case for individual concern about how our personal travel choices affect the climate. It is estimated that personal travel accounts for a 20-40 per cent share of Europe’s annual carbon emissions.

"Carbon friendly choices could reduce this share to 10 or 20 per cent without the need to give up travel," said Dr Borken-Kleefeld. "This figure is based on the same distances being covered, just with different transport modes. Hence, personal behaviour (and some of the structural decisions supporting it) is an important leverage in mitigation – or augmentation – of climate change."

A necessary evil?

While sharing a long car journey with two or three others in a small car could reduce the emissions per person to the equivalent of a train or coach ride, making the same trip alone in a large car could have just as negative an impact in terms of emissions as taking a flight.

The impact of air travel is largely down to the formation of contrails and cirrus clouds, as well as the indirect production of ozone. According to Dr Borken-Kleefeld, air travel is just one of the many modern day necessities which involves inflicting – and accepting – some negative drawbacks. This does not mean, however, that our approach to mitigating these effects can be lax.

"A great idea would be to have a budget – in terms of annual equivalent CO2 (CO2eq) emissions allowances, for example – which leaves everybody free to choose travel, consumption, housing and so on within its limits, just as we are limited in financial means and adapt our choices accordingly," he suggested.

"Unfortunately, political and public will to implement such a carbon budget seems to be very weak. The situation is made more complicated by the fact that, for best results, it should be on a global scale."

Could more be done?

As the Stern review pointed out, the more time we allow to slip by before taking decisive action, the more costly mitigation and adaptation to climate change will become. This cost may not necessarily be to us personally, but to our children and to peoples in Bangladesh, Eastern China, the Netherlands, on island states, and elsewhere. Is there more that could be done?

"Yes!" Dr Borken-Kleefeld replied emphatically. "The technology is there to drastically improve the fuel economy of cars, which would be (relatively) easy, would offer significant cost savings to consumers, and be a really feasible way to mitigate climate change."

In terms of totals, addressing the fuel economy of cars would target the biggest emission source and be relatively easy in comparison to measures on aircraft. In the aviation world, there are other courses which could be taken.

"If politicians really want to address the impact of air travel, why not consider a simple measure like not allowing more airports or airport extensions to be built?" Dr Borken-Kleefeld asked. "This should be effective in constraining demand and hence impact. However, all depends on the objectives – climate, economics, local labour and income – as well as political and public will."

Lessons to be learned

The authors believe that there are three key lessons to be learned from their paper, which was unusual in that it accounted for factors including vehicle efficiency and occupancy – aspects that are often overlooked by publicly available carbon calculators, for example. For academics, then, the analysis offers the most up-to-date numbers, with many variations in terms of load, fuel economy, metrics and time horizons.

As far as policy-makers are concerned, other issues should be pushed to the fore now that effective control of exhaust pollutants has proven beneficial in reducing short-lived climate forcers for ground transportation.

"Now, the important issues are the fuel efficiency of vehicles and low-carbon contents of fuel," noted Dr Borken-Kleefeld. "Aircraft, however, are a bit different and make high contributions from short-lived climate forcers which are much more difficult to mitigate. Air travel should therefore be climate-regulated in a specific way."

The climate researchers also have some pointers for members of the public wishing to reduce their climate impact, which may be ‘common sense’ to some, but which are worth reiterating.

"If you can, choose public transport like a train or coach for your holiday or business trip. When purchasing a new car, try to choose the one with highest fuel economy to save money and emissions over the following five years’ driving. When driving long-distance, don’t travel alone – it would be an inefficient trip.

"Try to use flying only as a very last resort – what is emitted thereby in one trip is hard to compensate for by other personal measures like cycling, a vegetarian diet or using green electricity."



Now that non-Western countries are submitting research, the theories are so adolescent and basically infantile in logic and misogynistic prejudice, it's appalling.

Commented Christina Richter on
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