23 Sep (CLIM) - McKinnon, Physics & Statistics of extreme heat
Speaker: Dr. Karen McKinnon, UCLA/ Johns Hopkins University
Title: The physics and statistics of extreme heat: land-atmosphere interactions and shifting distributions
Time: Wed, 23 Sep, 1:30-2:30 pm
Location: Exploratory Hall Room L111 or via Zoom (for Zoom link, email xdu5@gmu.edu)
Host: Aahelee Sarker
ABSTRACT: Heat extremes result from the convergence of atmospheric and land processes across multiple spatial and temporal scales. While we can be quite confident that heat extremes will become more frequent in a warming world, major uncertainties remain in terms of how and why they will change. Despite many recent high-impact heat waves, observations and climate models agree that the hottest summer temperatures have warmed at approximately the same pace as the median. Consistent with this result, much of the spatial pattern of changes in heatwave frequency, duration, and intensity can be explained by a shift in the mean temperature distribution, with climatological variance and skewness determining how warming translates into changes in different heatwave metrics. The relative changes in the median and tails are well-predicted by two components of the surface energy budget, the evaporative fraction and net surface radiation. While it has generally been thought that the evaporative fraction would decrease with warming, and therefore amplify heat extremes, we show that regions and days with strong land-atmosphere coupling tend to have smaller soil moisture reductions, thereby limiting the role of land surface changes in amplifying temperature extremes.
Bio: Karen McKinnon is a professor of Statistics and the Environment at the University of California, Los Angeles. Beginning in November 2026, she will join the Department of Environmental Health at Johns Hopkins University. Her research sits at the nexus of climate change and statistics, and is aimed at improving our understanding and prediction of climate extremes, variability, and change. She is a 2027 AMS Henry G. Houghton Awardee, a 2024 NSF CAREER awardee, a 2023 Kavli Fellow, and a 2021 Packard Fellow in Science and Engineering.
