Since the late 20^th century, significant changes have occurred in global climate patterns, largely resulting from increases of anthropogenic greenhouse gas emissions. Compared with moderate climate change, the extreme climate events usually exert larger impact on ecosystems and human health, i.e., the heat waves could increase death rate in a very short period of time. In this study, the state-of-art global climate model Community Earth System Model (CESM v1.0) was used for global climate simulations under newly developed emission scenarios. Two emission scenarios, one is moderate emission scenario Representative Community Pathways (RCP) 4.5 while the other is fossil fuel intensive scenario RCP 8.5, were chosen primarily aiming to compare the climate impact due to different anthropogenic emissions. Based upon these two scenarios, widespread increases in both heat wave durations and frequencies were found globally. The projected global average decadal heat wave duration in 2090s becomes two times and four times large as present climate in RCP 4.5 and 8.5 scenarios, respectively.  In addition, global average decadal heat wave frequency increased by 1.7 and 2.1 times compared with present climate in 2090s in RCP 4.5 and 8.5 scenarios, respectively. In order to take advantage of local detailed topography, land use data, we also downscaled CESM outputs to 4 km by 4 km Eastern US domain using Weather Research and Forecasting (WRF) Model. The evaluations between regional model outputs and global model outputs/observational data were performed for verifying the downscaled methodology.