CLIMATE CHANGE IMPACTS ON Sugarcane PRODUCTION IN SOUTHERN Brazil.

This study evaluated the effects of climate change on sugarcane yield, water use efficiency, and irrigation needs in Southern Brazil, based on downscaled outputs of a general circulation model (HadCM3) and a sugarcane growth model. The DSSAT/CANEGRO model was used to simulate the baseline and 6 future climate scenarios for sugarcane stalk and sucrose yields for the 2050s. Model parameters were derived from Brazilian field datasets. Simulation for the entire State of São Paulo, there were increases of 6.6% and 6.7%, respectively for stalk fresh mass (SFM) and sucrose mass per unit of area (SUCA). Considering only the area currently producing sugarcane (based on the sugarcane area mapped during the 2007/2008 growing season), SFM increased 10.0% on average and SUCA by 6.0%. The model’s sensitivity to air temperature, CO₂ concentration [CO₂] and rainfall was also analyzed. Besides increases in air temperature, the effects of [CO₂] on leaf water losses helped to explain the rise of SFM and SUCA for most of the simulated scenarios. The results showed that water use efficiency would be increased 5.2% as a consequence of higher [CO₂], which is important because of the current concern about water supply in Southern Brazil. Irrigation still would not be required for sugarcane production in the future, based on these results.