Future climate change will strengthen cotton production but have substantial environmental costs—A focus on Xinjiang by APSIM modelling

Assessing the potential impacts of climate change on cotton production, water consumption and carbon emissions is crucial for reducing water allocations and carbon emissions, especially in Xinjiang, a major cotton-producing region of China with an arid climate and water scarcity. In this study, we used the process-based crop model Agricultural Production Systems sIMulator (APSIM) to simulate the spatial and temporal variability of cotton yield, water consumption (ET), irrigation water requirement (IWR), irrigation water productivity (IWP), global warming potential (GWP), and greenhouse gas intensity (GHGI) in Xinjiang, and to estimate the total amount of cotton yield, water demand, and carbon emissions in North Xinjiang (NXJ) and South Xinjiang (SXJ). The results showed that the lint cotton yield in Xinjiang benefited from elevated temperature and CO₂ levels under SSP245 and peaked at 2334 kg/ha in the 2060s (14.1% higher than that in the historical period), while the positive effect of elevated CO₂ levels was eliminated by the rapid increase in temperature under SSP585 and peaked at 2219 kg/ha in the 2050s (11.6% higher than that in the historical period). Compared with their levels in 1981–2020, the IWR, GWP, and GHGI increased by 4.3–5.6%, 38.5–41.6%, and 25.1–25.8%, respectively, by the 2050s–2060s under SSP245 and SSP585, thus posing great challenges for water resource and carbon emission reductions in Xinjiang. Cotton production in SXJ would reach 2.87–3.24 million tons, dominating that in Xinjiang (55.1–56.2%) by the middle to end of this century but would cost 0.76–0.92 billion m³ more for irrigation and 0.28–0.59 million tons CO₂ eq more for GWP than in NXJ. These results suggest that future cotton production in Xinjiang will be limited by water and environmental pressures, especially after the 2060s, and that controlling carbon emissions in all industries and slowing the warming process will contribute to the sustainable development of cotton.