Assessing climate change impacts on sugarcane yield, crop water productivity, and nitrous oxide emissions across Brazil's bioenergy using the CSM-SAMUCA-sugarcane model

Sugarcane-based bioenergy systems are critical in Brazil's renewable energy sector, contributing significantly to global efforts to reduce fossil fuel dependence. However, climate change introduces uncertainties related to sugarcane yield, water use efficiency, and greenhouse gas emissions. Rising atmospheric carbon dioxide (CO 2 ) levels, increasing temperatures, and shifts in precipitation patterns are expected to impact Brazil's bioenergy cultivated areas, necessitating a comprehensive evaluation of their effects on sugarcane production and environmental sustainability. This study assessed the effects of rising CO 2 , temperature increases, and altered precipitation on sugarcane yield, crop water productivity (WP), and nitrous oxide (N 2 O) emissions across Brazil's bioenergy cultivation areas under future climate scenarios. We integrated the CSM-SAMUCA-Sugarcane model with the DSSAT-GHG module to simulate sugarcane systems across nine agroclimatic zones. Future projections (2040–2070) were based on 20 CMIP6 Global Climate Models (GCMs) under three Shared Socioeconomic Pathways (SSP1–2.6, SSP3–7.0, SSP5–8.5). SSP1–2.6 (low-emission scenario) showed minor yield changes, with some CO₂ fertilization gains. SSP3–7.0 (intermediate/high-emission scenario) may increase yield by up to 10 % due to warming and CO₂ effects. However, SSP5–8.5 (most extreme warming) and rainfall reductions increased yield variability. N₂O emissions may rise by 5–30 %, with intensities up to 40 % higher, driven by warmer soils and faster residue decomposition. WP responses varied: some regions gained from CO₂-induced efficiency, others declined due to soil moisture limits. Balancing yield improvements with N 2 O mitigation under climate change remains a challenge. Climate-resilient nitrogen and residue management strategies are essential to ensure sustainable bioenergy production in Brazil. • CSM-SAMUCA-Sugarcane simulated sugarcane yield, water productivity, and N 2 O emissions. • Future climate scenarios increased sugarcane yield in several agroclimatic zones. • N 2 O emissions from sugarcane are projected to increase between 5 % and 15 % by 2050. • Crop water productivity showed diverse responses across Brazil's sugarcane zones.