Beef Stew(ing) – what might the future look like for northern Australian beef in a warmer world?

Beef Stew(ing) – what might the future look like for northern Australian beef in a warmer world?

Across northern Australia's tropical and rangeland regions, grazing cattle are generally well acclimatized to the humid heat; however, heat stress is major cause of calf mortality and contributes to reduced fertility in heifers and bulls. This is both caused by the prolonged impacts from chronic heat stress that affect cattle in poor body condition, and heat events over a relatively short time that can lead to acute heat stress and higher risk of mortality. Heat stress in cattle is typically measured using the Temperature Humidity index (THI); however, the THI does not account for the heat gained or lost by an animal and assumes all cattle breeds are the same. A better suited metric that accounts for cattle breed diversity is the Heat Load index (HLI), which incorporates the effects of incoming solar, temperature, relative humidity and wind on heat lost or gained from cattle.

In this research, we will discuss our latest prototype forecast product development with respect to cattle heat stress that is being conducted through the Northern Australia Climate Program (NACP). This includes a 7-day forecast of Accumulated Heat Load using the Bureau of Meteorology's Australian Digital Forecast Database, a multi-week forecast of 'Cattle Comfort' using the Bureau's seasonal forecast system ACCESS-S2, and the first efforts to assess the likely future changes in cattle heat stress using CMIP6 models. We will discuss the challenges and opportunities for these products, and in turn, provide an assessment of what northern beef might face in a warmer world.