Caltech Logo

Environmental Science and Engineering Seminar

Wednesday, March 1, 2023
4:00pm to 5:00pm
Add to Cal
South Mudd 365
A new theory for heat extremes in a changing climate
Yi Zhang, University of California Berkeley,

Heatwaves cause great harm to societies, especially in midlatitude regions that are not adapted to high temperatures. An accurate projection for future heat extremes requires a fundamental understanding of the physical mechanisms. Several mechanistic drivers of heatwaves, such as atmospheric blocking and soil moisture-atmosphere feedback, are well-known for their ability to raise surface air temperature. However, what limits the maximum surface air temperature in heatwaves remains unclear, and this became evident during recent Northern Hemisphere heatwaves which achieved temperatures far beyond the upper tail of the observed statistical distribution.

Here, we present the hypothesis with corroborating evidence that convective instability limits annual maximum surface air temperatures over midlatitude land. We provide a theory for the upper bound of midlatitude temperatures, which accurately describes the observed relationship between temperatures at the surface and in the mid-troposphere. We also interpret recent extreme heatwaves using this theory and discuss how continental extreme temperatures will change with global warming.

For more information, please contact Bronagh Glaser by email at b[email protected] or visit Environmental Science and Engineering.