Evapotranspiration (ET) is the process by which water moves from the land to the atmosphere—either by evaporation from bare soil or open water, or by being released from plants through transpiration. Understanding what drives (or limits) ET is crucial to understanding how heatwaves and droughts develop. In recent decades, changes in ET have been driven by a few major factors: in some areas, declining soil moisture has caused large drops in ET, while in others, increased energy availability and changing plant behaviors have led to modest increases. Most modern climate models struggle to fully capture the soil moisture-driven declines in ET, but they do a better job capturing the modest ET increases driven by other factors.