Accurate regional temperature projections in China are vital for climate change mitigation and adaptation. Since some of the Coupled Model Intercomparison Project Phase 6 (CMIP6) climate models are identified as “too warm” with a tendency to overestimate future warming, this study introduces an observational attribution-constrained projection method to reduce uncertainties in regional temperature projections. By applying this method to the CMIP5 and CMIP6 models, we establish a robust linkage between observed and projected temperature changes across China. Using the optimal fingerprinting technique, we demonstrate the dominant influence of anthropogenic activities on regional temperature changes. Through application of the optimal estimates of scaling factors derived from this method, we constrain future temperature projections. Under high-emissions Representative Concentration Pathway (RCP8.5) and Shared Socioeconomic Pathway scenarios (SSP5-8.5), the unconstrained annual mean temperature changes for 2081–2100 relative to 1995–2014 are projected as 4.47°C (5th–95th percentile range: 3.38–6.23°C, hereafter the same) by CMIP5 and 5.24°C (3.60–7.76°C) by CMIP6. After constraint implementation, these projections decrease to 3.90°C (2.98–4.48°C) for CMIP5 and 4.35°C (3.49–5.11°C) for CMIP6, with reduced uncertainty ranges compared to original projections. The constrained method improves consistency between CMIP5 and CMIP6 simulations, reducing inter-model uncertainties and enhancing the reliability of China’s temperature change projections.

As the world’s largest potato producer, China plays a crucial role in global food security. However, the impacts of climate change on both the potential planting regions and climatic suitability of potato cultivation in China remain poorly quantified. In this study, potato planting zones were delineated based on the thermal requirements of potato, utilizing the temperature data from 2177 meteorological sites during 1961‒2020. A comprehensive climatic suitability index (CCSI) was developed by integrating temperature, light, and precipitation suitability indices, weighted through Agricultural Production Systems Simulator (APSIM)-Potato model simulation. During 1991‒2020, compared to 1961‒1990, the unsuitable and single-season planting regions decreased by 18% and 8%, while the multi-season and winter planting regions expanded by 93% and 6%, respectively. During 1961‒2020, the CCSI was highest in single-season planting regions (e.g., Northeast China and the north agro-pastoral ecotone), followed by multi-season and winter planting regions. During 1991‒2020, compared to 1961‒1990, CCSI of potato planting in the single-season planting region showed a slight decrease, but it increased by 1%‒2% in the multi-season and winter planting regions. These findings demonstrate that the increase in potato climate suitability supports the expansion of potato planting area and implementation of the “Potato as Staple Food” policy. Increased precipitation and temperature identify Northwest and Southwest China as the potential expansion regions for potato planting.