Extreme Weather in a Changing Climate

Abstract:

It is a real honor for me to get the opportunity to pay homage to Steve Schneider and his extensive accomplishments. I also treasured his friendship. Steve was known for being a great communicator and for his expertise in climate policy and solutions, along with being an outstanding scientist with many contributions to understanding the Earth’s climate system. One of the major challenges today to all of these areas is the changing trends in extreme weather under a changing climate. My focus in this presentation is to examine these issues by drawing on new research from my own team at Illinois. For example, climate change amplification in the Arctic has raised questions regarding its potential effects on extreme weather at mid-latitudes, especially the United States. In our studies, we find a statistically significant relationship between summer sea ice north of Alaska and geopotential height anomalies in the north Pacific during subsequent winter and spring months. The frequency of these semi-persistent height anomalies exhibits a long-term upward trend that amplify the jet stream off the West Coast of the U.S., driving more persistent precipitation patterns over certain regions of the United States, specifically in the West and Midwest parts of the country. Our results suggest that as sea ice in the Arctic north of Alaska continues to decrease, a more persistent ridge will form in areas adjacent to this location and affect storm tracks over the continental United States. In other studies, we are examining the effects of the changing climate on trends in extreme events throughout the continental U.S. We are also investigating changes in historical severe convective weather over the United States using reanalysis data, the NEXRAD/in situ gauge Climate Data Record (CDR) data set, and storm reports. After analyzing the ability of global climate models to represent the observed trends in severe-thunderstorm environments, projected future trends are also to be analyzed.