Over 5000 years of ensemble future climate simulations by 60 km global and 20 km regional atmospheric models

Abstract

n unprecedentedly large ensemble of climate simulations with a 60 km atmospheric general circulation model and dynamical downscaling with a 20 km regional climate model have been performed to obtain probabilistic future projections of low-frequency local-scale events. The climate of the latter half of the 20th century, the climate 4 K warmer than the pre-industrial climate, and the climate of the latter half of the 20th century without historical trends associated with the anthropogenic effect are simulated respectively more than 5000 years. From large ensemble simulations, probabilistic future changes in extreme events are available directly without using any statistical models. The atmospheric models are highly skillful in representing localized extreme events such as heavy precipitation and tropical cyclones. Moreover, mean climate changes in the models are consistent with those in the CMIP5 model ensembles. Therefore, the results enable the assessment of probabilistic change in localized severe events that have large uncertainty from internal variability. The simulation outputs are open to the public as a database called ?Database for Policy Decision-Making for Future Climate Change? (d4PDF), which is intended to be utilized for impact assessment studies and adaptation planning for global warming.