The Future Potential of Brazilian Sugarcane Ethanol with respect to Land Availability and Climate Change
Wednesday, 17 December 2014
Expanding sugarcane production on the 65.9 mha area identified by Brazilian government can provide a sustainable and low carbon intensive supply of liquid fuel to the world. However, such expansion is also subject to long-term climate changes. Variation in sugarcane yield at policy-relevant spatial and temporal scales can greatly influence the long-term potential of Brazilian. A process-based crop model (BioCro) is parameterized and calibrated for leaf photosynthesis and field productivity. Multi-site validation against observed stem yield of sugarcane cultivar RB72454 suggests that model can predict consistent yield (observed = 0.92 × predicted; R2 = 0.65) over a wide range of soil and environmental conditions in Brazil. Regional simulations based on national soil data and reanalysis climate data suggest that 1.938 petagram (Pg) of stem dry biomass can be harvested annually. Increasing temperature and [CO2] can partially compensate for yield decline due to reduced rainfall in future, by means of greater water use efficiency and rate of photosynthesis. Simulations using five GCMs climate data suggest that average productivity of harvested stem dry biomass may decline from 1.938 Pg year-1 to 1.544 Pg year-1 (1.243-2.066 Pg year-1) by 2045 in the absence of improved cultivars.