The figure of 1.3 g is right wrong!
The value of 1.3 g CO2 equivalent would be correct if the disposal of the card were not taken into account. However, since the entire life cycle of a product must be considered in a CFP analysis, the value is not correct. The CFP values actually reported are significantly higher: if the card were to be recycled, the value would already be 2.3 g. If it were disposed of via waste incineration (with heat recovery), the CFP value would be 6.1 g and thus only just below the calculated weight of the card of around 7.7 g. If disposed of in a landfill, the value would even rise to 9.0 g CO2 equivalent.
Why is this the case?
In contrast to the partial carbon footprint (pCFP), a carbon footprint (CFP) must always show the entire life cycle. The entire life cycle is therefore represented in a so-called product system for balancing purposes. In the case of the card, this consists of 6 individual sections, which are referred to as unit processes. The relevant inputs and outputs are determined for each of these unit processes, which are then combined to form a complete life cycle inventory analysis. The value of 1.3 g only represents the sum of the first 5 unit processes. In fact, the unit process (6) “Disposal card” still generates considerable GHG emissions, which significantly change the values.
Why 100 years?
Because time periods play an important role in determining the carbon footprint. On the one hand, the climate-relevant effectiveness of the gases is usually described using the Global Warming Potential in relation to a time horizon of 100 years (GWP100). Secondly, an observation period must always be specified. In the case of landfilling, this is 100 years for the card, as the decomposition products resulting from the decomposition of the card are determined or applied over this period. This means that if you do not dispose of the card for the next 100 years, the CO2 emissions calculated for it are not included in the balance.
But you certainly don’t want to wait that long!