Australian wheat yields plummet after decades of global heating, study finds

Scientists from Australia and China warned as global heating continues, wheat-growing conditions would become more challenging.

The number of positive IOD events had risen markedly in recent decades, corresponding with a drop in rainfall and falling yields.

In good years, the average wheat yield could reach 2.5 tonnes a hectare but in drier years with positive IOD events, the yield would drop well below 1.5 tonnes a hectare.

The researchers used models that account for other factors that can influence wheat yield, such as crop management, sowing time, or the varieties planted.

The study comes as Australia is being heavily affected by the alternate negative phase of the IOD that is contributing to major downpours across the south and east of the continent.

Dr Andrew King, a co-author of the study at the University of Melbourne, said research had shown the Indian Ocean was warming quickly and this was caused by emissions of greenhouse gases.

The areas in Australia most influenced by those positive IOD events overlapped the areas where wheat is grown.

The study found positive IOD events had become stronger than before and this had seen it take greater influence over wheat yields than other climate systems, such as El Niño or La Niña.

As greenhouse gases continue to rise in the atmosphere, this would probably see more positive IOD events causing more droughts.

Holding, who also works with campaign group Farmers for Climate Action, said improvements in wheat varieties, chemicals and fertilisers, and greater understanding of soils had meant yields had been held steady.

According to forecasts from the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES), 2022-23 could be the second-biggest wheat harvest on record.