How can winegrowers adapt to climate change? A participatory modeling approach in southern France

Climate change threatens wine growing systems in varying ways because of their high diversity, even at a local scale. This diversity needs to be considered when designing and assessing adaptation strategies to coordinate better with these diverse local conditions. We developed a participatory modeling approach to (1) design adaptation strategies in a viticultural watershed in southern France, (2) numerically and spatially evaluate their effects under future climatic conditions, and (3) discuss the results with stakeholders. We organized two sets of collective workshops, before and after a simulation phase. During the workshops, we designed four adaptation strategies that correspond to different ways to combine adaptation measures proposed by stakeholders. A spatially explicit model was used to evaluate the effects of six adaptation measures (late varieties, irrigation, reducing canopy size, adjusting cover cropping, reducing density, and shading) at field scale and combinations of them at watershed scale. Simulations were realized under a high-emissions climate change scenario RCP 8.5. Model-based evaluations were followed by discussions with stakeholders. The cost-effectiveness of adaptation strategies was estimated at farm scale using an indicator designed by the stakeholders. The spatial combination of adaptation measures in a viticultural watershed provided options for adapting wine growing systems to climate change. A delayed harvest strategy with currently available late varieties provided only minimal relief from high temperature during ripening. A water stress limitation strategy would compensate for production losses if disruptive adaptations (e.g., reduced density) were adopted and if more vineyards were irrigated. A relocation strategy would encourage premium wine production in the constrained mountainous areas, where grapevines systems are historically adapted to limited water conditions. A soil improvement strategy was mentioned but not evaluated in the model due to scarce data and literature on the possible improvement of soil water holding capacity. The sharing of knowledge between researchers, technical experts, and wine growers enabled the construction of a common understanding of the local impacts and adaptation potential to climate change in the watershed. In further research, this knowledge could help decision makers to define pathways for adaptive actions at farm scale.