Deteriorating climate conditions for Australian wheat production

Matthew O. Grant , Elisabeth Vogel, Anna M. Ukkola, Andy J Pitman, Andrew Hartley, Neal Hughes

Wheat yields are highly sensitive to climate extremes, but previous studies risk underestimating their influence due to a reliance on highly aggregated agricultural data. Here we combine nationwide farm-level agricultural data with machine learning to identify the key drivers of Australian wheat yield and assess how climate conditions for wheat production have changed over recent decades. We find that extreme events dominate climate impacts on wheat yield and explain 53-74% of yield variability across Australia’s wheat-growing states, with drought and late-season heatwaves having the largest impacts. This influence of extremes is more than double the estimates reported in previous studies that use spatially aggregated yield data. Between 1970 and 2020, 72% of the Australian wheat belt experienced a significant increase in growing season drought days, and over 90% experienced a significant increase in late-season heatwave intensity. These trends have driven a deterioration in Australia’s wheat-growing climate conditions. Advances in agronomic technology and management practices have so far offset this deterioration, masking emerging climate risks to production in one of the world's major wheat-exporting nations. Because Australia is a key supplier to global wheat markets, these risks extend beyond domestic production and threaten global food security. Our findings highlight the need to strengthen the resilience of Australian wheat production to protect both local and global wheat supplies.