Local ecological footprint using Principal Component Analysis: A case study of localities in Andalusia (Spain)

The quantity and quality of available information is one of the major constraints for the calculation of the ecological footprint, particularly for sub-national or sub-regional territorial levels. At the national or even regional level, the information that allows for computing the ecological footprint is generally available. However, when trying to calculate the footprint for lower-level territorial realities (e.g., cities or municipalities), this information is insufficient or non-existent. In this article, we propose an indirect method for calculating the ecological footprint of such territorial spaces through Principal Component Analysis. The case study utilises the ecological footprint of Andalusia (a Spanish region) as a starting point for footprint assignment to each of the 771 municipalities included in the Andalusian region. A set of variables related to the consumption levels in these municipalities has been utilised and is expressed in physical units. These variables make it possible to obtain a weighting factor to determine the ecological footprint of each municipality. This procedure also makes it possible to identify which variables or indicators have the greatest impact on the ecological footprint for a given territory. According to the results, the method also shows how inappropriate it is to consider the population as a way to distribute the ecological footprint; there are relevant differences between the weight of the population in municipalities and their generated footprint. There are also significant differences between the magnitude of economic indicators, such as GDP, and the estimated ecological footprint; for municipalities with higher income levels, the ecological impact is more than proportional to the weight of the monetary indicator