Man-made CO₂-emissions are generated in multiple sectors. In Denmark the bulk of our CO₂ equivalent emissions are generated in the agricultural sector, in the supply (energy) sector, and in the transportation sector.[i] In the national Danish CO₂-accounts emissions from international transport are currently not accounted for, making it difficult to place the responsibility. Consequently, responsibility is transferred to the individual organization or citizen (until we find a way to account for international emissions in our national accounts). [i]

International aviation currently accounts for about 2% of global emissions, expected to increase dramatically in the years to come. 95% of traffic pertains to passenger travel, while 85% of it is of a private nature. Remarkably, only about 3% of the Earth’s citizens are flying regularly. In 2020 air traffic had increase by 70% since 2005, expected to increase by an additional 300% as we approach 2050[i]. [i]

Although flying, until we invent sustainable fuels, necessarily will emit relatively large amounts of CO₂ per traveled km, CO₂ offsetting, by means of planting trees, is a sustainable way to make a difference. Planting trees is good for the environment and creates local jobs. The fastest and cheapest way we in the private sector can offset our CO₂-emissions, is by planting mangrove trees (forests in saltwater areas) in countries with low wages, as exemplified by DAT[i]. Mangrove trees pull about 20 tons CO₂ from the atmosphere per hectare of forest[ii]. That is twice as effective as trees planted on land, while simultaneously protecting coast lines and functioning as a kindergarten for wildlife living among the roots. [i] (Danish airline specialized in domestic air travel in Denmark) [ii] Donato (2011),

Click here to see the latest pictures from Grow For It’s area in Antsanitia, Madagascar, latest updated in May, 2020, as we achieved our Grove Partner level with Eden Projects. On the Antsanitia site alone, Grow For It has planted donor trees for amounts corresponding to the planting of half a million trees. Put in another way; on this one site Grow For It has planted trees to offset for about 1000 tons of yearly CO₂-emissions.

Calculation of CO₂-emissions from international aviation

In 2019, the Technical University of Göteborg, Chalmers, developed a new tool for calculating air traffic pollution as a function of distance. The tool has been created due to the increasing negative impact of air traffic on the environment (See calculations in the Appendix 1 below).

The Chalmers tool:

The tool is easy to use and based on historical data from 1990-2017. Below we have made a comparison of the most popular tools used to calculate the CO₂-emissions from air travel.

We believe, as IPCC recommends, that it is vital to look – not only at pure CO₂-emissions – but also account for the effect of the emissions happening in high altitude. This is also known as radiative forcing and can be seen as white condensation trails[i] on the blue sky. [i] Kondensstriber = strålingspåvirkning = Radiative forcing (link to .pdf on IPCC web site)

When we include radiative forcing, using Chalmers’ figures, we end up at an average figure of around 0,300 kg of CO₂–equivalent (CO₂e) emissions per flown kilometer with economy class (see Table 2b in Appendix 1 below). Economy class is important as the figure would be higher for more expensive tickets, due to fewer passengers per flight. We therefore recommend to plant trees corresponding to 300 g CO₂ emitted per flown km on economy class.

Appendix 1: Comparison of different calculators’ methods to CO₂e / km Table 1a) Comparison of kg CO₂e emitted per person round trip for typical distances, excl. radiative forcing (see sources below), economy class:

Tabel 1b) Comparison of kg CO2e emitted per km excl. radiative forcing, economy class:

Tabel 2a) Comparison of typical distances incl. radiative forcing, economy class:

2b) Comparison of kg CO2e emitted per km incl. radiative forcing, economy class:

Sources for the tables:,13.00/170/20000 (Chalmers)



[1] (Danish airline specialized in domestic air travel in Denmark)

[1] Donato (2011),

[1] Kondensstriber = strålingspåvirkning = Radiative forcing (link to .pdf on IPCC web site)