Severe Weather in the United States Under a Changing Climate

There has been an increase in some key types of extreme weather events, especially in heat waves and large precipitation events, in the U.S. (and throughout the world) over the last 50 years. Over recent decades, we are now breaking more than twice as many heat records as cold records in the U.S. There has also been an increase in the number of historically top 1% of heavy precipitation events across the U.S. The pattern of precipitation change is one of increases generally at higher northern latitudes (because as the atmosphere warms it holds more moisture) and drying in the tropics and subtropics over land. Scientific analyses are also indicating a strong link between changing trends in severe weather events and the changing climate. Every weather event that happens nowadays takes place in the context of the changes in the background climate system. Every event is influenced by many factors. Human-induced climate change is now a factor in all weather events. This presentation provides a discussion of the current understanding of severe weather in relation to the science of climate change, with a special emphasis on the issues and remaining uncertainties affecting our future.