Evaluating Compound Risks of Heatwaves and Droughts on Crop Yield and Food Security in Morocco

In an era marked by climate change, heatwaves and droughts have increasingly begun to co-occur within a single growing season, significantly impacting crop yields in key agricultural regions globally. Against this backdrop, the current study is dedicated to quantitatively evaluating the effects of these combined hot-dry episodes on agricultural productivity in Morocco, a country where such climatic extremes pose a significant threat to food security and economic stability. Utilizing high-resolution gridded precipitation and temperature data that closely aligns with 29 ground station observations, we calculate the Standardized Precipitation Index (SPI) and the Standardized Temperature Index (STI) across Moroccan arable regions in the agricultural season (September-May) during 1981-2018. Employing a vine-copula conditional probability model, the study explores the complex interactions between drought and heatwaves and their joint impact on vegetation, as indicated by the Normalized Difference Vegetation Index (NDVI). The focus is on identifying the conditional probability of vegetation loss under multiple compound dry-hot episodes. The findings highlight that the combined effects of droughts and heatwaves can have catastrophic consequences for crop yields, especially during the growth season. This underscores the critical need to assess their compound impact on agricultural productivity, rather than examining each factor separately. This study provides a robust understanding of compound hot-dry events and their impacts on crop yields, highlighting the emerging need for comprehensive adaptation strategies that bolster agricultural resilience and support sustainable productivity in the face of evolving climatic challenges.

Keywords: Compound, drought, heat waves, NDVI, vine-copula, conditional probability.