Enhancing sugarcane yield resilience under a changing climate: adaptive irrigation and varietal strategies in Reunion Island

Variations in rainfall patterns, whether in quantity or frequency, pose a significant challenge that sugarcane crops must adapt to in the context of climate change. This study aimed to assess the impact of future climate scenarios from 2015 to 2100 on sugarcane yield at a regional scale in Reunion Island and to identify adaptation practices to mitigate the impact of climate. Different irrigation regimes were tested to assess the impact on growth and future water requirements using the Mosicas sugarcane crop growth model at a 3 x 3 km resolution. High-resolution climate data for three IPCC future scenarios (RCP 2.5, 4.5, and 8.5) were obtained from the BRIO project, conducted by Météo France, the French national weather service. Results showed that, despite a favorable increase in temperature, changes in precipitation patterns resulted in minimal yield change at the island scale compared to the current period. However, the impact of climate change varied significantly across different climatic areas on the island. On the south-west coast, yields decreased significantly (by -8% and -4% on average in 2060 and 2090, respectively), while on the east and north-east coasts at high altitudes, yields increased (by +9% and +17% in 2060 and 2090). Overall, water irrigation demand increased by 15 and 24% in 2060 and 2090, respectively, on average across scenarios. It was found that irrigating non-irrigated areas reduced the negative impact of climate change, particularly in high altitudes in the south and north-east. Additionally, the simulation of more drought-resistant varieties was able to limit the negative impact of climate change in areas facing increasing water deficits without changing the irrigation regime. Finally, this study illustrated how areas currently less suitable for sugarcane production, such as high-altitude areas, will become more favorable due to climate change. Adaptation methods, such as changes in irrigation management or the adoption of more drought-tolerant varieties, were identified as effective strategies to cope with climate change and maximize the sugarcane’s potential in a more favorable temperature environment.