L.S. RUSSELL

Division of Tropical Crops and Pastures, CSIRO, Brisbane, Queensland, Australia.

Abstract

Global warming is predicted to have less impact on northern than southern Australia due to temperature increase being least at the equator and increasing polewards.
Estimates for northern Australia suggest an increase in temperature of 1 or 2 °C in northern coastal areas and 2 to 4 °C inland by the year 2030. Summer rainfall could increase by + 10 to + 20%.
Warming in inland regions could result in a southwards shift of the northern limits of the sheep industry, the frost zone and the winter growing species. The shift could be of the order of 1. 5 degrees of latitude for 1 °C increase in temperature.
The seasonality and monsoonal nature of rainfall in northern Australia will increase the importance of soil characteristics, especially for the Vertisols. Within regions, day length and solar radiation will not change but rainfall and temperature will change, creating new climates to which indigenous and introduced species may not be adapted. Increased water use efficiency due to higher CO₂; levels and stomatal closure during the day could offset the predicted negative effect of higher temperature on plant growth. Pasture legumes, being C₃ plants, could benefit from increased atmospheric carbon dioxide levels.
Research is needed to develop more comprehensive pasture-plant models and to provide better predictions using regional climate model output.