Responsible travel:
Experience the world on less CO₂

The world has changed in the past few years, and travel with it. Trips have become events to look forward to with a renewed sense of wonder and appreciation. And now there’s a new way to travel – one that’s gentler on the places we’ve been missing.

Next time you search for flights, try the Least CO₂ sorter. It sorts flights by their CO₂ emissions, so you get a more transparent view of your options and can make more sustainable travel decisions.

Try the Least CO₂ sorter and see how easy it is

All around the world, people are trying to live more sustainably in their daily lives. But many don’t have enough information to make climate-friendly travel decisions when planning and on trips.

So many factors affect the amount of CO₂ emitted that it’s next to impossible for a traveler to figure it out, because it depends on many different factors — like cabin class, aircraft type, flight profile and cargo load.

That’s why we teamed up with the best

We’ve developed our Least CO₂ sorter in close collaboration with German non-profit atmosfair, one of the world’s leading climate consulting organizations. This new tool gives highly accurate calculations of each flight’s CO₂ emissions in an easy overview.

Airline rating

An overall rating of how well an airline is performing on multiple CO₂-reducing factors.

Passenger load

Fully booked planes have more passengers, which means less CO₂ per passenger.

Cabin class

More passengers can fly in economy class seats because they take up less space, which means less CO₂ per passenger.

Aircraft type

Modern aircraft are up to 30% more fuel-efficient than older models.

Flying direct

Take-off and landing use the most jet fuel on every flight. Flying direct means you only do this once.

An eco-conscious way to compare flights

With the Least CO₂ sorter, you can immediately see how flights stack up environmentally. It shows the average amount of CO₂ emissions per person for all flight routes in your search result, plus emissions per person for each flight and how those compare to the average.

Responsible travel starts by comparing all your options

In routes where trains and busses are available, these options will also appear in your search results – so you can compare all your options and find the best way to get there on less CO₂.

The prices and percentages shown are for illustrative purposes only.

Tips on how to travel sustainably

Saving on CO₂ is more than choosing the right flight. There are choices we can all make to reduce our carbon footprint throughout the entire journey — from planning to transport to activities on location. Every little choice can add up to make a big difference. Browse through our sustainable travel tips below and be inspired.

10 ways to make your carbon footprint cleaner

Economy seats are smaller and lighter than Business or First class, so you can fit more of them on a plane — meaning fewer CO₂ emissions per passenger.

Reduce plastic and save some bucks by bringing your own food onboard in a reusable container.

Visit outdoor markets to try the fresh produce, drink locally-made beer and wine, avoid international chain restaurants and buy souvenirs made in the area.

It takes energy to make every ounce of weight airborne, so ask yourself if what you’re packing is really necessary.

And fill it up after you’ve passed security to stay hydrated on the plane. Super handy when exploring your destination too!

Instead of jet skiing, paragliding or four-wheeling, which all pollute, try downhill skiing, snorkeling and bicycling.

Choose tours owned and operated by locals. They’ll also have an interest in the well-being of their communities.

Before heading to the airport, unplug your electronics (especially TVs and computers) and turn down the heating and refrigerator.

No one likes hanging out on a littered beach. Clean up especially non-biodegradable trash so you can relax with a good conscience.

Avoid all-you-can-eat food buffets and ask for your leftovers “to go” – perfect for a midnight snack.

Tips and tricks for finding more sustainable flights

Make your next flight easier on the environment by following these tips when booking

Read more

FAQs: CO₂ and responsible travel

In 2017, global flight traffic emitted more than 859 million tons 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 5 ½ miles, account for 4% to 5% of global warming.
How much CO₂ a single plane emits depends on factors like aircraft type, distance traveled and passenger load. You can see how much your flight will emit by using our Least CO₂ sorter in your search.

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 organizations 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 Discover article.

Taking most of the common forms of transportation into account – plane, train, car, biking and walking – it’s no surprise that biking and walking are the least CO₂-intensive ways to get around. Some say that biking 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 282 lbs. CO₂eq by plane, 220 lbs. CO₂eq by car and only 46 lbs. CO₂eq by train.

Say you do a flight search on momondo and see two good possibilities: one that emits 4,982 lbs. of CO₂ and one that emits 4,156 lbs.g CO₂ (19% less). So how does this 826 lbs. of difference in CO₂ compare to the rest of your carbon footprint? According to this calculator, an 826 lb. (19%) CO₂ reduction is the equivalent of driving a passenger car 930 miles.

    Tell us what’s on your mind

    Do you have a great sustainable travel tip or improvement suggestions on our Least CO₂ sorter? We want to hear it.


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    We believe in a future where we as travelers use less CO₂

    The well-being of this planet involves us all. That’s why, just as momondo creates transparency on flight prices, we’re also giving you transparency on the environmental impact of flights.

    But we know there is no simple solution. We will continue to develop more eco-travel initiatives to help protect our planet for future generations.

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