Climate warming enhances sugarcane yield and increases annual harvest frequency in northern coastal New South Wales, Australia

CONTEXT: Australia is a leading exporter of raw sugar on the global market. Rising temperatures could enable sugarcane to achieve harvestable yields in a 1-year growth cycle instead of the traditional 2-year cycle in the subtropical regions of northern New South Wales (NSW). However, no study has evaluated how climate change impacts annual harvest frequency, leaving a critical gap in understanding sugarcane production's future in Australia. 

OBJECTIVE: We aim to quantify the impacts of climate change on sugarcane yield and annual harvest frequency and identify the main climatic drivers that determine yield change. METHODS: We used sugarcane yield data collected from three milling regions, Condong, Broadwater, and Harwood, to validate the QCANE sugarcane model in northern coastal NSW. The validated model was then driven by climate data downscaled from 27 global climate models under the Coupled Model Intercomparison Project Phase 6 to simulate sugarcane growth and sugar accumulations. RESULTS AND CONCLUSIONS: The QCANE model showed strong agreement between simulated and observed values, with an R² of 0.83 for stalk fresh weight (FW) and 0.80 for sucrose weight (SW), and nRMSE values of 9.4 % for FW and 10.0 % for SW. Under rising emissions (SSP126 to SSP585), yield projections indicated increases by the end of the 21st century, with FW rising by 6–34 Mg ha⁻¹ (i.e., 6–29 %), biomass dry weight (DW) by 2–11 Mg ha⁻¹ (6–29 %), and SW by 1–7 Mg ha⁻¹ (10–46 %) across the three study sites. Additionally, the annual harvest frequency was expected to increase from 50 to 80 % during the baseline period (1981–2020) to 68–96 %, with a greater proportion of future years supporting frequent annual harvests. Climate variables accounted for 93–96 % of the yield variation, with elevated atmospheric CO₂ concentration as the dominant contributor to yield increases. SIGNIFICANCE: These findings highlight opportunities to enhance sugarcane production by adopting a 1-year harvest cycle under future climate conditions, providing valuable insights for the sugarcane industry to adapt and thrive in the face of climate change.