To Fly or Drive? Minimizing Climate Impact Isn’t Simple

It seems like an easy question: Will my climate impact be greater if I drive somewhere far away, or fly there?  But the answer, according to a new paper in Environmental Science and Technology, depends on the time-frame you’re considering. European researchers used climate chemistry models to study the impacts of planes, trains, automobiles, and ships for both passenger and freight travel on the climate response as indicated by the resulting temperature change. Their findings are relatively straightforward for freight: shipping and rail have the lowest impacts, and light trucks and air have the highest. Standard truck transport falls in the middle. For passengers, however, air travel has the highest impact on short-term warming (per hour traveled), but over the long term, car travel has an equal or higher impact per unit distance. Rail and bus travel both have lower impact than car travel.

Researcher Jens Borken-Kleefeld explained the air/car difference to ScienceDaily: “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 kilometer. 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.”