Basis for our CO2 Calculations

A tree is planted.

A tree is planted.

Photo: Asociación Patuca

The data used as a basis for the Naturefund CO2 calculators come from the Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit, the Umweltbundesamt, the Gesellschaft für Konsum-forschungerman and the United Nations Framework Convention on Climate Change (UNFCCC).

CO2 emissions from cars

The data used as a basis for the CO2 calculators come from the Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit (BMU) (German Federal Ministry of Environment, Nature Conservation and Nuclear Safety).

According to the BMU average levels of CO2 emissions by cars are as follows:

  • a petrol car emits 2.32 kg of CO2;
  • a diesel car emits 2.63 kg of CO2 per litre;
  • per kilogram of natural gas, 2.23 kg of CO2 are produced.

Example calculation for a petrol car

For example a VW Golf needs on average 8 litres of petrol per 100 km. If you drive just 12,500 km in a year, the calculation is as follows:                                              

12,500 x 0.08 x 2.32 = 2,320 kg CO2 per year

So, if you have a petrol car all you need to do is follow the above and multiply the km per year, by the litres of petrol per km, by 2.32 and that will give you the amount of CO2 produced per year.

For our CO2 calculator we have used the data for a petrol car. In order to calculate the amount of CO2 produced by a diesel car and to find out the number of trees you would need in order to neutralize this, all you need to do is multiply by 1.13. For a car that runs on natural gas, you need to multiply by 0.96.

CO2 emissions from aeroplanes

According to the BMU, for every person on board an aeroplane, an average of 369 g of CO2 are emitted per air kilometre. The BMU calculates the effects on the climate from air traffic.

These effects on the climate are also designated as an RFI (Radiative Forcing Index) factor. When substances that are damaging to the climate reach the atmosphere at high altitude, they have a stronger effect than CO2 emissions close to the ground.

CO2 emissions from the home

The BMU provides the following levels of CO2 emissions for the varous sources of energy:

  • 0.04 kg CO2 per kilowatt hour of green energy;
  • 0.61 kg CO2 per kilowatt hour of energy;
  • 0.24 kg CO2 per killowatt hour of natural gas;
  • 0.3 kg CO2 per kilowatt hour of oil;
  • 0.13 kg CO2 per kilowatt hour of heating;
  • 0.1 kg CO2 per kilowatt hour of wood.

The data for the use of heating per square metre for the various energy sources come from the Gesellschaft für Konsumforschung, 'Energieverbrauch der privaten Haushalte und des Sektors Gewerbe, Handel und Dienstleistung', 2004.

CO2 emissions from food

The data for CO2 emissions from food come from the 'Die CO2 Bilanz des Bürgers', 2007, BMU. In Germany an average of 1.55 tonnes of CO2 is released per person per year as a result of food consumption.

This value increases for those who eat a lot of meat or who consume a lot of frozen foods. It decreases for those with a reduced consumption of meat or who are vegetarian, for those who buy local or mainly organic products.

Absorption of CO2 by trees

The data we use to calculate the absorption of CO2 by trees are also average values. Trees vary greatly in their absorption of CO2 depending on the type of tree, the amount of light, life expectancy, geographical location and degree of latitude, the quality of the soil and many other factors.

As a basis for our calculations for the amount of CO2 absorbed by trees, we have applied data from the UN Climate Secretariat and the United Nations Framework Convention on Climate Change (UNFCCC). Whilst in central Europe an average tree absorbs around 10kg CO2 per year, this figure is considerably higher for an average tree in the Tropics due to, among other things, much faster growth. 

A tree may absorb 500 kg CO2

In the beginning young trees absorb relatively little CO2, but as they grow taller they begin to absorb a large amount. It is true that trees die partially each year and by losing their leaves and branches they are also emitting CO2

Naturefund reforests in the tropics of Central America and Madagascar as well as in the highlands of Bolivia or in North Spain. The capacity of trees to store CO2 differs. Therefore, we calculate an average absorption of 500 kg of CO2 per tree.