Responsible travel:
Now there’s an eco-friendlier way to compare flights

In 2017, global flight traffic emitted more than 859 million tonnes of CO₂, which accounted for approx. 2% of global man-made CO₂ emissions. But flying also emits non-carbon emissions like ozone, soot particles and nitrogen oxide that, when emitted at altitudes over 9 km, account for 4% to 5% of global warming.

How much CO₂ a single plane emits depends on factors like aircraft type, distance travelled and passenger load. You can see how much your flight will emit by using our Least CO₂ sorter in your search.

Source: International Air Transport Association, Carbon Brief

Flight compensation is a way to “make up for” the CO₂ emissions that were used to fly a passenger to their final destination by allowing the passenger to contribute to projects that will either remove existing CO₂ from the atmosphere (e.g. planting trees) or reduce future CO₂ emissions (e.g. solar farms or research into sustainable aviation fuel).

Many organisations and companies – including some airline companies – have CO₂ calculators that let you calculate how much CO₂ your flight has emitted and then offset your portion of those emissions. The most important thing to remember is that if you choose to offset your flight, make sure your money is helping fund a validated project. Look for projects that have e.g. the CDM Gold Standard and VCS certification labels, which means their environmental effects are closely monitored.

You can read more about flight compensation in this article.

Taking most of the common forms of transportation into account – plane, train, car, cycling and walking – it’s no surprise that biking and walking are the least CO₂-intensive ways to get around. Some say that cycling actually emits less than walking because we require less food-fueled energy to go the same distance by bike than by foot, which translates into fewer CO₂ emissions that went into growing, packaging and transporting the food. (If you want to dig even deeper, you can also factor in CO₂ emitted from our bodies during the walk/bike ride, which would be fewer on the bike ride because, even though we may be breathing harder, we would still be breathing less overall in that distance than walking.)

Of course, it’s hard for most people to bike or walk longer distances. Between planes, trains and cars, trains emit the least CO₂ by far. According to one study, a trip from London to Edinburgh emits 128 kg CO₂eq by plane, 100 kg CO₂eq by car and only 21 kg CO₂eq by train.

Say you do a flight search on KAYAK and see two good possibilities: one that emits 2,260 kg of CO₂ and one that emits 1,885 kg CO₂ (19% less). So how does this 375 kg of difference in CO₂ compare to the rest of your carbon footprint? According to this calculator, a 375 kg (19%) CO₂ reduction is the equivalent of driving a passenger car 1,500 km.