Simulations of Sugarcane Yields for Increased CO<sub>2</sub> Concentrations in Mackay, Australia — ASN Events

Simulations of Sugarcane Yields for Increased CO2 Concentrations in Mackay, Australia (7743)

Justin Sexton 1 2 , Yvette Everingham 1 2 , Geoff Inman-Bamber 3 , Chris Stokes 4
  1. School of Engineering and Physical Sciences, James Cook University, Townsville
  2. Centre for Tropical Environmental and Sustainability Science, Townsville
  3. Crop Science Consulting, Townsville
  4. Plant Industries, CSIRO, Townsville

Sugarcane has the potential to supply renewable alternatives to meet future energy needs. Understanding the impact climate change will have on the sugarcane industry is critical. Crop modelling software can be used to simulate the effects of higher CO2 concentrations on cane yield. An improved crop simulator was used to model yields for the Mackay sugarcane-growing region. Sugarcane yields were simulated for a low (B1) and high (A2) emissions scenario, accounting for the effect of increased CO2 concentrations at a whole crop level.  Climate data from eleven statistically downscaled general circulation models (GCMs) were used to estimate regional sugarcane yields for the period 1971 to 2000 (CO2 concentration of 345 ppm). Future GCM projections for 2046 to 2065 were simulated for both low (B1; 493 ppm) and high (A2; 548 ppm) emissions scenarios. Projected yields for each scenario were compared with simulated yields from the base period. Confidence intervals were used to estimate the 25th, 50th and 75th percentiles of paired model differences in yield projections. A change in future yields was considered “plausible” if the confidence interval for the 50th percentile did not include zero. An increase in cane yield was considered “highly plausible” if the confidence intervals for the 25th and 50th percentiles captured only positive values. A decrease was considered highly plausible if confidence intervals for the 50th and 75th percentiles captured only negative values. Simulations produced a plausible increase in projected yields under a low emission scenario (B1).  However, under the higher emission scenario (A2) no change in projected yields was considered plausible.  The difference between scenarios is an important result as recent climate change research suggests higher CO2 concentrations are more likely. A more detailed understanding of the impacts of climate change on crop yields is essential to help industry devise robust adaptation strategies. Robust adaptation will prepare industry for the challenges of an increase or decrease in cane yield under a changing climate.