Washington: A new study has found that driving a car increases global temperature in the long run more than making the same long-distance journey by air.
However, in the short run travelling by air has a larger adverse climate impact because airplanes strongly affect short-lived warming processes at high altitudes.
Jens Borken-Kleefeld and colleagues used a suite of climate chemistry models to consider the climate effects of all long- and short-lived gases, aerosols and cloud effects, not just carbon dioxide, resulting from transport worldwide.
They concluded that in the long run the global temperature increase from a car trip will be on average 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. Passenger trains and buses cause four to five times less impact than automobile travel for every mile a passenger travels.
"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," explained Borken-Kleefeld.
"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,” Borken-Kleefeld added.
The study appears in ACS’ Environmental Science & Technology.