A New Theory for Heat Extremes in a Changing Climate

Heatwaves damage societies worldwide and are intensifying with global warming. An accurate projection for future heat extremes requires a fundamental understanding of the physical mechanisms. Here, we demonstrate the role of convective instability in limiting extreme temperatures and wet-bulb temperatures (heat stress) over land. We then provide a theory for an upper bound of midlatitude surface temperatures and a theory for tropical extreme wet-bulb temperatures. Finally, we discuss how heat extremes will change with global warming based on the theory.