Mega-fires can adversely impact air quality in the United States and the impact is likely to become more severe in the future due to the possibly more frequent and intense mega-fires in response to the projected climate change. This study investigates mega-fires and their air quality impacts with a focus on the future trends under changing climate change fuel conditions and will provide information for understanding the questions stated in the Task 7 of the JFSP RFA 2011. A comprehensive approach of data analysis, algorithm development, and numerical modeling will be used to understand the areas and seasons of present mega-fires, project their future trends, and simulate fuel loading and smoke transport. The dynamical downscaling of regional climate change will be used to calculate present and future fire potential indices and analyze atmospheric patterns and properties as thresholds for mega-fire breakout. Ensemble results will be obtained for multiple combinations of global-regional climate model simulations. The objectives include: (1) to build mega-fire probability functions with respect to drought levels measured by fire indices and atmospheric patterns and property thresholds, (2) to project future mega-fires, (3) to obtain present and future fuel loading based on fuel conditions and simulated carbon pools, (4) to simulate smoke trajectories using a smoke transport model, and (5) to evaluate the smoke impacts on air quality in large U.S. urban areas. The research products will be delivered to field managers and researchers through a workshop or training session, conference presentations, journal publications, and webpage. The results are expected to provide essential information for further evaluation of the potential smoke impacts on human health. The applications of dynamical downscaling of regional climate change scenarios and change in fuel loading should improve our understanding of future mega-fire trends and impacts obtained from recent studies. The projection of future trends in mega-fires will provide useful information to fire and land managers and policy makers for developing climate change adaptation and mitigation strategies.