Carbon Offsets


Carbon Offsets

A Guide for Frequent Flyers

I have a confession to make: I am a frequent flyer. I love traveling the world, visiting new countries, learning about their histories, and experiencing their cultures. Nothing inspires me more than exploring the most remote corners of the globe and seeing its stunning beauty with my own eyes. I am rarely happier than when I sit at the gate waiting to get on a plane that will take me to a new destination far away. I have set foot on all seven continents, I have visited 93 countries thus far and I am not nearly done. My personal motto and the title of my travel blog is Hans Christian Andersen’s quote “To Travel is to Live”.

Many would consider this a contradiction in terms, but I also think of myself as an environmentalist. I have seen the devasting impacts of environmental destruction, loss of natural habitats, deforestation, receding glaciers, draughts and floods in many parts of world with my own eyes. And I believe climate change is the greatest danger and most important challenge humanity will be facing over the next few decades.

Carbon offsetting is not the solution to the problem, but I believe it can play an important role, and at this stage it is the best way to reconcile a love for travelling with a concern for the planet. I have been compensating for the emissions from my flights using carbon offset projects for many years. But I have recently done a lot more research into it, and I wanted to share some of what I have learned. I hope to provide some guidance on how to calculate your greenhouse gas emissions from air travel and how to find the most effective ways to compensate for it using carbon offset schemes.

In the following section, I will give an overview of air travel’s impact on global greenhouse gas emissions. Then I will show, using my own example, how to calculate your carbon footprint from air travel. I will examine the idea of carbon offsets in general and address some of the criticism. And in the final section I will provide options for various providers and schemes and show which projects I have chosen for my own offsets.

In recent years air travel has attracted increased focus from climate activists. The concept of ‘flight shaming’, which originated in Sweden, tries to guilt travelers into switching from planes to other modes of travel or into giving up flying entirely. While no one doubts that flying is one of the least environmentally friendly ways to travel, I do think it is important to put it into perspective. So, let’s take a look at the science to find out what the contribution of global air traffic to overall greenhouse gas emissions is.

The graphs and figures in this section are largely based on data from the IPCC (the United Nations’ Intergovernmental Panel on Climate Change) and its Fifth Assessment Report, which was published in 2014. First, we want to see the relative contributions from all sources of man-made greenhouse gas emissions, which is shown in the following graph:

Global energy production (which includes the transportation sector) drives 72% of global greenhouse gas emissions. The largest slice within the energy sector comes from electricity & heat generation, followed by transportation and manufacturing & construction. As a share of the total, transportation is responsible for 15% of all emissions. It is worth noting that this graph includes all greenhouse gases. If we were to look at CO2 emission in isolation, then the contribution of the transportation sector would be somewhat larger at 24%. It is also important to point out, that transportation is the faster growing sector, mainly driven by increased mobility of the populations of developing countries. The next graph demonstrates this trend and provides a further breakdown of the transportation emissions by type.

It may not come as a surprise that by far the largest contributor within the transportation sector is road traffic. 72% of all emissions come from road vehicles (including transportation of people and goods). Adding up the percentages for domestic and international aviation we see that 10.6% of the total is driven by planes. Similar, but more recent (2017), data comes from the EU which shows a slightly higher percentage for aviation at 13.9%.

Thus, given that the transportation sector as a whole is responsible for 15% of global emissions, we find that air travel contributes somewhere between 1.6% and 2.1% to all man-made greenhouse gas emissions. This is a surprisingly small percentage. As a comparison, burping cows alone contribute almost three times as much.

I certainly do not mean to trivialize the climate impact from flying, but I do think it is important to put it into perspective. And the fact is, even if we were to eliminate all airplanes tomorrow, we would hardly see a measurable effect on expected increases in global temperatures, if other contributors remained unchanged. To really make a difference, humanity should be directing most of its efforts towards switching electricity generation and heating to renewables, electrifying road vehicles, reducing emissions from the steel and cement industry, and rethinking our approach to agriculture and meat production. All these sources have a much larger impact on the earth’s climate than the aviation sector. The airline industry and travelers certainly have a role to play in reducing emissions, but air travel is not the key problem we need focus on.

Air travel contributes only about 2% to greenhouse gas emissions on a global level. However, at an individual level the picture can look quite different. In the case of a frequent flyer, like myself, flying is likely responsible for a significant majority of that person’s overall carbon footprint. Using my own example, here I am going to demonstrate how to quantify the contribution from air travel to your carbon emissions.

I have recorded and tracked all my flights using a website called In the year 2019, I visited 14 countries across five continents, taking 47 segments of various short- and long-haul flights. These added up to a total distance of 169,060 kilometers flown, which would be enough to circle the globe more than 4 times. Here is a map of my 2019 flights.

To translate this into carbon dioxide emissions, I can utilize a variety of different online calculators, most of which are quite straightforward to use. Typically, you just enter the departure and arrival airports and the class you flew in, and the calculator returns an amount of CO2 in metric tonnes. (For my American readers, a metric tonne is equal to 2,204 pounds.) The calculators weight the impact of each flight by the class of travel. Since a business class seat takes up a larger portion of the plane, it makes sense to allocate a larger share of the flight’s emissions to that seat. You should always try to calculate the impact of each flight separately, rather than just providing the total distance flown. The reason for this is that short-haul flights generally emit more CO2 on a per kilometer basis since jet engines produce much higher emissions during taking off and ascending compared to cruising at altitude.

I have used several of the most popular calculators, and I found that the results are not very consistent. There appears to be a range of up to +/- 30% between them. This isn’t too surprising, since all of these calculations use estimations based on averages. The actual emissions of a specific flight depend on many factors, such as the type of aircraft, weather conditions on the day, the exact route flown, how many seats are empty and how much luggage is being transported. So, you need to make some allowance for the fact that calculating your CO2 impact is not an exact science, and these calculators will only give you a general guideline. In Appendix A I have listed more details and some comparison for five of the best calculators I have found.

To figure out my own emissions, I have used You can see the detailed results of my calculation in Appendix B, where I have listed all my 2019 flights and the carbon emissions for each. (If you do not have the time to enter the details of every single flight, I have created a shortcut table, which will give you a reasonable estimate just based on number of short-, medium- and long-haul flights.)

My total for the year came to 18.1 tonnes of CO2. This is already a large amount, but it is not the whole story yet. When considering the total climate impact of flying, we must take into account the fact that jet engines emit not only CO2 gas, but several other climate relevant substances, such as water vapor, nitrogen oxide and sulfur particles. And there is a significant difference in the greenhouse effect created by these substances, depending on whether they are emitted near ground level or at the typical cruising altitude of an airliner. The exact mechanisms of these effects are quite complex and not completely understood yet, but essentially, greenhouse gases emitted at higher altitudes, have a larger warming effect due to differences in atmospheric pressure and temperatures. Furthermore, cloud formation from aircraft contrails can have an additional significant impact. (It is interesting to note, that these non-CO2 emissions have a much shorter ‘lifetime’ in the atmosphere than CO2 gas, which will take centuries to be absorbed naturally. That means, any reduction in air travel or even the re-routing of some flights, could have a much more immediate impact on these other pollutants.)

To account for the additional effects of non-CO2 emissions, I need to multiply my total by a so-called ‘radiative forcing factor’. There remains great uncertainty about the exact value of this factor but based on the best available scientific evidence it is generally recommended to be set at 1.9. This means the climate impact of flying is almost twice as severe as it would be based on CO2 emissions alone. (Note that some of the calculators, I have listed in the Appendix, automatically make this radiative forcing adjustment. So always check this when you use them!) Multiplying 18.1 tonnes by 1.9, my new total now becomes 34.4 tonnes. And that is an exceptionally large amount. To put this in context, the average per capita annual carbon emission in the US is about 16 tonnes, in Germany it is around 10 tonnes. My frequent flying alone puts my carbon footprint well above the average person in any developed country. The remainder of this article discusses, what I can do about this.

The idea of offsetting or compensating emissions is something that works for greenhouse gases, but not for any other type of environmental pollution. If I threw out plastic trash or caused an oil spill on a beach, it would make no sense to ‘offset’ the contamination by cleaning up a different beach somewhere else in the world. The damage from the original pollution would still be there. In the case of greenhouse gas emissions, however, the environmental impact is almost exclusively global. Carbon dioxide is not a pollutant in itself. It has essentially no negative consequences on a local level. The only measure that counts, is the total concentration of CO2 in the earth’s atmosphere. This makes it in principle possible to neutralize carbon emissions in one part of the world through a reduction in emissions somewhere else. For example, CO2 that is emitted by driving my car in Europe, could be compensated by a green energy or tree planting project, that removes the same amount of CO2 from the atmosphere or prevents it from being emitted, somewhere in the developing world. That is why the basic idea of carbon offsets makes sense.

Carbon offset schemes have been around for some time. The idea was first conceived in the 1980’s and started to take off after the signing of the Kyoto protocol in 1997. I want to point out that here I am only talking about the voluntary carbon offset market, which allows consumers and companies to offset their carbon emissions on a purely voluntary basis. There is also a much larger global compliance market, in which corporations and governments execute legally binding carbon credit commitments to comply with the caps determined by the Kyoto protocol. Although still much smaller, the voluntary carbon offset market has continued to increase in size over the last few years. According to a study by Forest Trends, a non-profit research organization, in 2018 offsets accounting for 98 million tonnes of carbon dioxide were purchased for a total of USD 295 million. Despite its increase in popularity, carbon offsetting has its critics. Before going into more detail, let me address the two main objections to the idea of carbon offsets.

One prominent objection is based on the narrative that carbon offsetting provides people an excuse for not changing their behavior. It is claimed that buying offsets only serves to give people a clean conscience, but in fact distracts from solving the real problem. Some critics even compare carbon offsetting to the catholic church’s medieval practice of indulgences, which allowed wealthy sinners to pay to have their sins forgiven. I think this argument is complete nonsense. First, as I explained above, the idea of offsets makes a lot of sense from a scientific point of view. Any project that prevents an increase or even reduces carbon emissions anywhere in the world, has a beneficial effect on the CO2 concentration in the atmosphere. Second, I also cannot imagine that anyone would fly more often, only because they can offset their emissions. On the contrary, I believe that travelers, who put in the effort to compensate for their emissions, are much more aware of their responsibility and significantly more likely to think twice about whether a flight is really necessary, or whether is can be done using other means.

The second main criticism is that many schemes do not deliver the promised offsets or are even outright scams. This is a very legitimate concern, which deserves to be discussed in more detail. I think there are two separate questions to be addressed. Firstly, “Are the promised carbon savings really happening?”, and secondly, “Are they additional carbon savings that are only happening because of my contribution?”. Or in other words: “Am I just paying for something that would have been done anyway?”. We will never be able to answer these questions with absolute certainty, but there are ways to minimize this risk by choosing the right providers and projects. The carbon offset industry has developed various certifications and standards to ensure buyers are getting their promised offsets. Some providers even give you a guarantee that, should the additional carbon savings turn out smaller than expected, they will invest in another project.

The most widely used certification for voluntary carbon offset projects is the Verified Carbon Standard (VCS), which has been developed and is managed by Verra, a non-profit organization founded in 2005. They have certified almost 1,600 projects to date, and they provide independent assessment and auditing to ensure projects achieve measurable carbon savings. Another popular standard is the Gold Standard, which was founded by the WWF and other NGOs in 2003. Gold Standard certified projects not only have to prove their carbon savings, but also must adhere to certain sustainable development standards. The website for Gold Standard has a list of certified projects all over the world, and you can purchase offsets directly through them.

The United Nations also grant certifications of emission reductions through their Clean Development Mechanism (CDM), which provides verification and ongoing monitoring of carbon offset projects and issues so-called Certified Emission Reductions units (CERs). Each project goes through a thorough vetting process and, like the Gold Standard, projects receiving CERs must prove other co-benefits, such as social and economic development goals.

In Germany, the ‘Stiftung Warentest’, the country’s largest consumer testing organization, conducted a review of several offset providers in 2018. It rated them according to the quality of compensation, transparency as well as compliance and controls. Six providers were tested, and three of them received the highest mark of ‘Sehr Gut’. I have listed these three providers in Appendix C, and I have used one of them for part of my offsets.

In summary, I believe that by using reputable providers and certified projects, you can have a high degree of confidence that your money spent does deliver the promised carbon savings. In the following section I will go into more detail of the types of projects that are available and their costs.

There is a great variety of carbon offset projects and providers available. Projects can be classified broadly into two main categories — natural climate solutions and technological solutions. Natural solutions, which have become the larger category in recent years, are mainly focused on forestry and land usage projects, such as forest protection initiatives, tree planting projects or carbon storage in soil through regenerative farming projects.

Technological solutions include renewable energy projects, waste disposal projects, industrial carbon capture, as well as energy saving and efficiency projects, such as supply of household devices like improved cooking stoves. In recent years, the share of large scale solar and wind farm projects has been reduced within the voluntary offset market. The reason for this is that prices for wind and solar electricity generation have dropped to such a degree, that they are now economically competitive with most other power projects. Thus, it no longer makes sense to include them in the voluntary offset market, since they are being built by utilities for economic reasons anyway.

A significant majority of carbon offset projects are based in the developing world, for the simple reason that it is often much cheaper and more effective to reduce or prevent emissions in poorer countries. These projects are also more likely to ensure marginal contributions, meaning they could not have been financed through other means. Many of these projects have additional environmental, social or economic benefits unrelated to climate change, such as providing local employment, empowering women, educating children, alleviating poverty, or protecting habitats for endangered species.
Finding carbon offset projects to invest in is as easy as a quick Google search. Most of the online calculators I have listed in Appendix A, have direct links to offset projects. In order to ensure you only pick high quality and certified projects, both the United Nations Carbon Offset Platform at and the website of the Gold Standard at are excellent sources. If you do not want to spend the time selecting a specific project yourself, you can pick providers, such as Atmosfair ( They have a standard price per tonne of offset, which they invest in a variety of projects.

Prices among different projects and providers can vary substantially. The projects on the United Nations website are generally very cheap, ranging from $1 to $10 per tonne of offset. Those on the Gold Standard platform tend to be a bit more expensive ranging between $10 to $20 dollars, while some of the German providers are the most expensive at 23 Euros (about $25) per tonne. I have no evidence to suggest that higher prices are in any way correlated to higher quality projects or better guaranteed results. Price differences are likely a function of the type of project and local labor costs. However, it is important to stress that even the most expensive of these voluntary offsets are still way too cheap. Unfortunately, they do not yet reflect the true environmental cost of emissions. The World Bank estimates that the cost of a tonne of carbon dioxide needs to be between $40 to $80 to achieve the goals of the Paris climate agreement. These low prices of offsets reflect the fact that the supply of projects still outstrips demand significantly.

Coming back to my own example, let me show you which projects I have picked. As calculated in the previous section, my flights for the year 2019 caused the equivalent of 34 tonnes of carbon emissions. Given the variation among the different calculators, I have decided to round that up to an even 40 tonnes of offsets. I chose to split my offsets among several providers, supporting projects in Latin America, Asia and Africa. To start with, I bought 10 tonnes of offset through Atmosfair, which was the winner of the above-mentioned consumer testing in Germany. I then selected six different projects, from three different platforms, and purchased 5 tonnes of offsets in each. In Appendix C, I provided more details of each of these projects. I have no reason to believe that the projects I picked are in anyway superior to others. I simply wanted to diversify my investment among different countries and different types of projects, which each of them having additional social and environmental benefits.
Since I used a combination of high-cost and low-cost providers, I ended up with a total cost of 557.25 USD, or an average of 14 USD per tonne. While you can get an even cheaper average cost by focusing on the cheapest projects, this is still not a lot. It is only a small single digit percentage of the overall cost of a flight ticket.

Climate change is one of the greatest challenges humanity has ever faced. It is an issue that affects every person on the globe, and one that we can only tackle through a massive global effort, that combines governmental, technological and individual contributions. I am in no way suggesting that carbon offset schemes are the solution to the problem, but I do believe that they can play a small part in the overall effort.

Being able to travel the globe is an incredible privilege, that almost no one in previous generations in human history ever had, and most people in the world still do not have today. Traveling and responsible tourism have numerous benefits for the countries being visited, as many poor countries crucially depend on the income from tourism. And even more importantly, traveling has huge benefits for the one who travels. No one has ever put it better than Mark Twain when he said, “Travel is fatal to prejudice, bigotry and narrow mindedness.”

I feel strongly that the benefits of traveling even by airplane, far outweigh the downsides from its environmental impact. I will not only keep on traveling myself, but I will continue to encourage others to venture abroad and see the world. And carbon offsets are one way to do this more responsibly. By using my own example I have tried to demonstrate, that calculating and compensating for your carbon emissions from air travel is straightforward and surprisingly cheap, that you can feel confident in the effectiveness of your offsets by using independently certified and reliable providers, and that many projects have significant additional social and environmental benefits. I will continue to invest in carbon offsets myself, and I will continue to research the most effective ways and impactful projects to do this. I believe carbon offsetting can be an effective intermediate step between now and the time when we all fly in electrically powered planes charged using electricity generated from renewable sources.

Happy traveling, everyone!

Appendix A: List of online calculators

A google search for carbon footprint calculator provides a large number of links and calculators. Here are some of the better ones I have found:

This is a calculator from a very reputable organization. The International Civil Aviation Organization (ICAO) is a UN agency. I found their calculator to be a bit limited for my purposes, since it does not separate premium economy from business class, and seems to be missing some of the smaller airports around the world.

MyClimate is a Swiss based foundation, that sells carbon offsets. They have carbon impact calculators not only for flights, but for all other activities. Their calculator is quite good and immediately provides you the cost of offsetting each flight.

Offsetters is a Canadian based advisory firm, that provides carbon management solutions to individuals and corporations. They have a simple carbon calculator for flight and car journeys.

Greentripper belongs to a consulting firm called CO2Logic, based in Belgium and the US. They provide advisory and carbon offsetting solutions to companies. I found their calculator to be among the best. It includes a breakdown for all cabin classes and provides interesting comparison data of your emissions.  

This is the calculator I ended up using, as it provides a lot of detailed breakdowns, and it contains all the small airports in the obscure places I tend to travel to

In order to compare the results from these five calculators, I have used them to calculate the CO2 impact of an economy return flight from Hong Kong to London. Here are the results:

While three of them give reasonably consistent results, the ICAO and Greentripper calculators appear to be outliers on the low and high end, respectively. 

Appendix B: My 2019 Flights

If you are a frequent flyer, it is quite a bit of effort to calculate the emissions from every single flight in this manner. To safe you some time, I have created this rough guideline on a per flight basis, which will give you a reasonable estimate:

                    CO2 emissions per flight in economy class:
                    Short haul (up to 2 hours): 0.25 t
                    Medium haul (2 to 6 hours): 0.5 t
                    Long Haul (> 6 hours):  1.25 t

These estimates already include the radiative forcing adjustment, and you just need to multiply them by a factor of 1.5 for a premium economy class flight and by a factor of 3 for business class. 

Appendix C: My Offset Projects

Stiftung Warentest, the largest German consumer testing organization, reviewed 6 large carbon offset providers in a 2018 study. Three among them received the highest mark of “sehr gut’. They were:

  • Atmosfair ( ):
    They are mainly focused on clean energy projects in developing countries, at a cost of € 23 per tonne.
  • Klimakollekte ( )
    Their focus is more towards small scale projects (such as energy efficient cooking stoves) in rural areas of South Asia, Africa and Central America. The price per tonne is of € 23.
  • Primaklima ( ) :
    Their projects in Africa and South America are focused on planting trees as well as preventing deforestation, at a cost of € 15 per tonne. 

These above providers generally do not let you choose specific projects yourself, but instead invest your funds across a number of projects. If, instead, you are looking to invest in a particular type of offset or country, there are many websites and providers, where you can buy your offsets using a specific project. The following three are the ones I have used, and which have a large number of certified projects:

  • The United Nations Carbon offset platform:

  • The Gold Standard platform:

  • The Cool Effect platform:

For my own offsets for 2019, I decide to split my contribution among several providers and projects:

  • 10 tonnes at Atmosfair at € 23 per tonne.
    This was the best rated provider in the German consumer test. They invest your funds across several projects, and don’t allow you to choose a specific project yourself. 
  • 5 tonnes each in 6 different projects, of which 3 are in Africa, 2 in Asia and 1 in South America:
    • Ethiopian Forest Regeneration Cooperative – a project to regenerate and protect native forests in the Ethiopian highlands.
      $18 per tonne
    • Cleaner and safer stoves in Malawi - a project to provide improved cooking stoves throughout Malawi, where 98% of families still cook using firewood and charcoal.
      $15 per tonne
    • Grassland, Water and Wildlife - a project to protect 4,100 square kilometers of cloud forests and savannah woodlands in southern Kenya.
      $7.69 per tonne
    • Angkor Bio Cogen Rice Husk Power Project – a renewable energy project in Cambodia to utilize rice husks as bio fuel for electricity generation.
      $3.50 per tonne
    • Solar Water Heater Program in India – a project that distributes solar water heaters across urban areas in western India to replace electric water heaters.
      $6.95 per tonne
    • Alto Mayo Protected Forest – a project to help protect 1,800 square kilometers of tropical rain forest from deforestation in Peru.
      $8.79 per tonne 

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