Integrated Spatio-temporal model of land-use change: a focus on Mediterranean agriculture under global changes

Session C3: Spatio-Temporal Modelling and Integration

Global climate and socio-economic changes determine the patterns of the allocation and trade of resources in all markets. Top-Down computable general equilibrium (CGE) models ignoring ecosystem constraints, look at the effects of global trends and generate trajectories of socio-economic indicators. Those models are commonly used to analyse the evolution of global economies, under the pressure of climate change drivers, but their approach impose substantial simplifications in terms of spatial aggregation and interactions between socio-economic and environmental variables. When considering adaptation of coupled socio-ecological systems to climate change, their inherent complexity and non-linearity and their spatial and temporal variabilities put the usefulness of consolidated CGE approaches under question for long term projections. Thus, other methodological approaches such as Bottom-Up approaches are explored. These models utilise mechanistic knowledge of ecosystems and incorporate behavioural diversity of economic agents in an integrated manner to study their interactions with the surrounding ecosystem and their bounded perceptions of the changing world. This work explores the integration of the T-D and B-U approaches, with CGE models providing the macro-economic trends under the effects of global change scenarios and agent- based models (ABM) used to simulate grid-based land use change dynamics, with consideration of spatial and temporal variabilities. We focus on how global change may affect land-use allocation at the local to regional level, under the influence of limited natural resources, land and water in particular. We specifically explore how constrains and competition for natural resources may induce non-linearities and discontinuities in agro-ecosystems behaviour. With the purpose to develop an approach that could be implemented worldwide as a means for zooming down from the global to the regional and local scale, an ABM prototype was developed in three test areas around the Mediterranean Basin, in agricultural regions of Tunisia, Italy and Spain. Starting with simplified and averaged settings; we sequentially introduce the available information about spatial and temporal variability and simulate the dynamics of water and land-use allocations and their consequences on economic performances. The coherency of the outcomes of ABM simulations with the macro trends provided by the CGE model is discussed in view of possible further developments in terms of improved integrated multi-scale simulation of global change scenarios and economic development.