Quantifying the desertification impact in Life Cycle Assessment

MONTSERRAT NUÑEZ; CIVIT, B; PERE MUÑOZ; ARENA, AP; JOAN RIERADEVALL; ASSUMPCIÓ ANTÓN

Montpellier

Conferencia; Environmental & Integrated Assessment of Complex Systems; 2011

Montpellier Supagro

Resumen: An innovative contribution to include an impact category until now never modelled in life cycle assessment (LCA): the desertification impact. Currently, LCA is rapidly progressing in order to account for land use impacts on the functions of ecosystems. In this way, methods addressing the effect of human activities on a number of ecosystem services have been recently proposed (e.g., biotic production, climate regulation, erosion regulation). One special type of land use impact that affect the quantity and quality of ecosystem service delivery in dry lands is desertification. The main consequence of desertification is the irreversible soil degradation and consequently, the expansion of deserts. In spite of the environmental consequences of desertification, so far it has been an issue overlooked in LCA methods. Extension of the LCA methodology to incorporate the desertification environmental impact. The method is illustrated with a case study. For the inventory (LCI), the multi-indicator method requires the estimation of four environmental variables: one linked to the activity evaluated (soil erosion) and three related to the location where the activity takes place (aridity index, aquifer overexploitation and fire risk). Based on these four variables, characterisation factors (CF) were developed for the main natural regions, i.e., ecoregions, of the world. CFs range from 0 to 10. An impact assessment model (LCIA) was also proposed. To show the suitability of the method, the desertification impact from growing food and energy crops in Spain and Argentina was compared. Only the agricultural stage was included in the assessment. Eight out of the fifteen ecoregions were classified as at risk of desertification: tropical/subtropical desert, tropical/subtropical steppe, Mediterranean, savanna, temperate desert, temperate steppe, prairie and marine. The tropical/subtropical desert region had the greatest risk of desertification (CF=7.6), followed by the tropical/subtropical steppe and the Mediterranean areas, both of which score 6.3. Aridity index and soil erosion are the most important variables that trigger desertification.   The LCIA model may be applicable to quantify the desertification impact of any kind of human activity in dry lands, as shown with the agricultural case study. The method should be further calibrated with new case studies encompassing the overall life cycle of the products.