Cars far worse than planes for long term emissions damage

Published on Wednesday 4 August 2010 14:13

CAR travel has a greater long-term impact on global warming than flying because it produces more longer-lasting carbon dioxide, according to new research.

A team of Austrian and Norwegian scientists said this outweighed the larger short-term impact caused by aircraft, which increased global temperatures four times more than cars over the same distance.

This is because of the extra impact of CO2 and other emissions at high altitudes.

The study also showed trains and buses caused four to five times less impact than cars for every kilometre a passenger travelled.

The researchers said several climate chemistry research techniques had been used for the first time to investigate the effects of all long and short-lived gases and cloud effects produced by transport.

Dr Jens Borken-Kleefeld, of the International Institute for Applied Systems Analysis in Austria, who led the research, said: "As planes fly at high altitudes, their impact on ozone and clouds is disproportionately high, though short-lived.

"Although the exact magnitude is uncertain, the net effect is a strong, short-term, temperature increase. Car travel emits more carbon dioxide than air travel per passenger kilometre. As carbon dioxide remains in the atmosphere longer than the other gases, cars have a more harmful impact on climate change in the long term."

The study, published in the journal Environmental Science & Technology, also showed that moving freight by plane rather than lorry over the same distance increased global temperatures by between seven and 35 times.

By contrast, the research found that shipping caused 25 times less warming in the long run.

However, environmental campaigners said the study did not make a meaningful comparison between cars and planes.

Jeff Gazzard, of the Aviation Environment Federation, said: "Long-term car greenhouse gas emissions will have a greater impact on climate change than flying - nobody disputes this.

"But it is easier to reduce vehicle emissions than those of kerosene-dependent aircraft - there are no hybrid planes, for instance. And aviation emissions are growing at a fast pace.

"Using a low-occupancy car versus a high-occupancy, large modern aircraft to make per-kilometre efficiency claims and comparisons regarding hypothetical long-distance travel is unclear and unhelpful.

WWF Scotland director Dr Richard Dixon said: "Our understanding of the impact of aviation on climate change continues to evolve and this important study shows that planes produce a spike of climate pollution at first while cars produce a longer term climate-changing boost."

He added: "Scotland is probably the only country in the world which includes aviation emissions in our climate targets and this study confirms the danger of continued unchecked growth in aviation emissions."