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Urban heat waves (UHWs) are strongly associated with socioeconomic impacts. Here, we use an urban climate emulator combined with large ensemble global climate simulations to show that, at the urban scale a large proportion of the variability results from the model structural uncertainty in projecting UHWs in the coming decades under climate change. Omission of this uncertainty would considerably underestimate the risk of UHW. Results show that, for cities in four high-stake regions – the Great Lakes of North America, Southern Europe, Central India, and North China – a virtually unlikely (0.01% probability) UHW projected by single-model ensembles ismore »estimated by our model with probabilities of 23.73%, 4.24%, 1.56%, and 14.76% respectively in 2061–2070 under a high-emission scenario. Our findings suggest that for urban-scale extremes, policymakers and stakeholders will have to plan for larger uncertainties than what a single model predicts if decisions are informed based on urban climate simulations.

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Antiferroelectric (AFE) materials owing to their double-loop-shaped electric-field ( E ) dependent polarization ( P ) are considered quite promising for energy-storage capacitors. Among the large family of AFE materials, the AgNbO 3 composition is attractive not only because it is environmentally friendly, but also because it has high recoverable energy storage density ( W rec ). However, the reported values of W rec < 4 J cm −3 in Ag(Nb 0.85 Ta 0.15 )O 3 multilayer capacitors are lower than that of the corresponding monolithic ceramic. This is attributed to high leakage current density ( J ) and inferiormore »breakdown strength (BDS) in multilayer structures. Here we demonstrate that MnO 2 doping not only effectively reduces the J value and results in slim P – E loops, but also enhances the breakdown strength (BDS). Multilayer capacitors with composition Ag(Nb 0.85 Ta 0.15 )O 3 + 0.25 wt% MnO 2 (ANT + Mn) demonstrated an excellent W rec = 7.9 J cm −3 and efficiency η = 71%. Extensive investigations were conducted on ANT + Mn multilayer capacitors to demonstrate the role of strain engineering in enhancing the maximum polarization ( P max ) and Δ P values. Results reveal the effect of built-in stress in the active layers of multilayer capacitors on the magnitude of P max , remanent polarization ( P r ) and W rec , and provide guidance towards the development of high energy storage density in multilayer capacitors.« less