Future Projections of summer Tibetan Plateau temperature based on the combined influence of sea surface temperature and soil moisture

Accurate projections of future warming characteristics in the Tibetan Plateau (TP) are essential for regional ecosystem stability and socioeconomic development and for understanding its role in modulating the Asian Monsoon and broader-scale climate patterns. This study evaluated and selected optimal CMIP6 models by combining an observation-based physical constraint—the synergistic influence of soil moisture anomalies and sea surface temperature anomalies on summer TP surface air temperature (SAT)—with an assessment of SAT spatiotemporal variations. Four multi-model ensemble methods were compared, and the random forest (RF) method was found to most effectively reduce temporal and spatial biases in historical simulations, thus providing a more reliable basis for future projections of summer SAT over the TP. Based on 10 optimal models, the RF-based projections show that SSP1-2.6 scenario, the TP exhibits significant warming trend (0.38°C/10a) in early-term future (2015–2044) but stagnates (0.03°C/10) during the mid- and long-term future (2045–2100). Under the SSP2-4.5 scenario, the TP SAT shows a significant warming trend (0.33°C/10a) during 2015–2070, then slows to 0.14°C/10a. Under the SSP5-8.5 scenario, the TP SAT maintains rapid warming (0.60°C/10a) throughout 2015–2100. The RF-based projections indicate stronger future warming (particularly in western TP) compared to the conventional multi-model ensemble mean (MME) of non-optimized 18 models (MME-18). These results highlight the risk of underestimating TP warming without proper model optimization, warranting particular attention on this vulnerable region.