Sydney, Oct 21 (IANS) Travelling by car increases the earth's temperature more in the long run than covering the same distance by air, researchers say.

However, in the short term, air travel has more impact on global temperatures as planes affect the short-lived warming processes at high altitudes.

A team led by Jens Borken-Kleefeld of the International Institute for Applied Systems Analysis, Australia, compared the impact of different means of transport, reports Environmental Science & Technology.

The researchers for the first time used a number of climate chemistry models to consider the effects of all long-and-short-lived gases, aerosols and cloud effects, not just carbon dioxide, resulting from worldwide transportation.

They concluded that in the long run, the global temperature increase from a car trip will tend to be higher than from a plane journey of the same distance.

However, in the first years after the journey, air travel increases global temperatures four times more than car travel, a statement said.

Trains and buses cause four to five times lesser impact than automobiles for every mile of distance covered.

"As planes fly at high altitudes, their impact on ozone and clouds is disproportionately high, though short lived," explains Borken-Kleefeld..

"Although the exact magnitude is uncertain, the net effect is a strong, short-term, temperature increase," she added.

"Car travel emits more carbon dioxide than air travel per passenger mile. 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," he said.