A framework to assess climate change effects on surface air temperature and soil moisture and application to Southwestern France

A comprehensive framework for climate change assessment is a prerequisite for managing multiple risks related to climate extremes, such as droughts, floods, or compound extreme events. It is also useful for addressing the diverging interests of stakeholders in finding regional adaptation solutions. Here, we design such a framework and a general methodology to assess the evolution of regional climate. Both mean values and extreme event characteristics of surface air temperature and soil moisture are analysed, including the likelihood of compound hot-dry, hot-wet, cold-dry, and cold-wet extreme conditions. These analyses are conducted for each month to investigate a variety of climate change impacts. The methodology is designed to be generic and easily applicable to any region of the world. It provides a foundational basis for initiating dialogue with local decision-makers, which will subsequently allow for further refinement of climatic impact-driver indices and analyses to produce tailored climate services. This work reports an application to Southwestern France, a region vulnerable to both floods and droughts with severe impacts on natural ecosystems and human societies. Drying and warming are expected throughout the year, with more pronounced effects in summer. This study highlights the complexity of designing adaptation solutions and the need for in-depth and comprehensive analyses of the evolution of local climate conditions. Specifically, Southwestern France is expected to experience an increase in drought frequency and intensity, while the region might still have to cope with the opposite phenomenon, floods.