Drought in wheat – Past and future trends

Abstract

Understanding how climate is varying and is likely affecting crop productivity in the coming decades is essential for global food security. Climate change studies predict an increase in temperature and more rainfall variability in future decades, which is likely to affect crops grown in water-limited environments. Complex interactions between genotype, environment and management impact on drought patterns (e.g. feedback of plant growth on water depletion) and crop productivity. To account for those interactions, the APSIM-Wheat model was used to identify water-stress environment types for 60 representative locations (22 regions) across the Australian wheatbelt (Chenu et al. 2013). Simulations were performed using historical climate records and for a selection of general circulation models for future climate scenario RCP8.5 provided by the Coupled Model Intercomparison Project Phase 5 (CMIP5). Results indicate that severe drought is a major recurrent problem across the wheatbelt, with a 44% frequency on average over the last century. Projections into the future revealed a lot of variability across climate models, with a consensus for an increased occurrence of severe drought in West of Australia and a decreasing occurrence of severe stress in the East. The latter result was largely due to shorter crop cycles (a result of warmer temperatures), increased water use efficiency (resulting from increased CO2 levels), and in some cases, increased local rainfall. However, drought is projected to remain a major issue across the large majority of the wheatbelt.

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