Life Cycle Assessment at the regional scale: innovative insights based on the systems approach used for uncertainty characterization

International audienceRapidly increasing population growth and food requirements call for increases in agricultural production, especially in irrigated areas. Environmental impacts arising from farming intensification in groundwater irrigated areas worldwide are manifold and the Life Cycle Assessment (LCA) is very relevant for assessing these impacts. But a regional LCA can not be done by transferring the “standard” product-oriented methodology to this meso-scale, especially in a context of data scarcity. Our objective is to propose a methodology to build a regional-scale Life Cycle Inventory (LCI) that would account for farming system diversity, avoid double counting and make clear allocation rules within this multi product system. We propose to base this methodology on the Agrarian System Diagnosis (ASD). This approach leads to a typology of farming systems which reflects the different agricultural exploitation modes existing on a regional scale. Enquiries are then carried out in farms representative of each type in order to build the inventory, which leads to a reduction of the uncertainty. This approach was applied on a case study located in Tunisia. Nine existing farming system archetypes and their main agricultural practices were identified and linked to their natural and socio-economic conditions. This typology goes beyond the farming system structure to describe its functioning and dynamics. Being a valuable approach for building a regional LCI, the agrarian system diagnosis could also be useful when assessing the environmental impacts of agricultural products at farm and crop scale. Indeed, this method allows us to build a typology of realistic situations instead of a virtual average system, and to support better allocation for multi product systems