Future risk of decadal megadrought events over eastern China based on IPO-constrained precipitation

A reliable projection of future risk of decadal megadrought event is crucial for adaption and mitigation over eastern China to future climate changes. However, large uncertainties are induced by emission scenarios, model structures, and internal variability in current model simulation. Using a 50-member ensemble of simulations from the Community Earth System Model Version 2 Large Ensemble (CESM2-LE), it is found that, under the same emission scenario, internal variability contributes a large part to the total uncertainties of decadal precipitation variability over eastern China, and the interdecadal Pacific oscillation (IPO), could contribute about 30% to internal uncertainty during future period (2021–2080). Then, an emergent constraint based on IPO is applied to the model simulated precipitation. Finally, constrained precipitation changes show that northern China will have a high megadrought risk in the 2050s to 2060s, and Yangtze River Valley will have a high megadrought risk in the 2030s to 2040s. These will have great benefit to specific strategies of social infrastructure in the future.