Evaporative demand (E0) both drives and responds to droughts based on interactions across the land surface-atmosphere interface, and can be exploited to signal agricultural, hydrologic, and ecological droughts. In this chapter, we argue that using a fully physically based measure of E0 moves the drought community toward a more complete understanding of drought processes that will enhance its abilities with regard to early warning and drought monitoring in the present day and drought-risk assessment under future climate change scenarios. We examine regional characteristics in E0 and their behavior during droughts in the recent historical period across different hydroclimates. We review physical mechanisms driving extremes in E0 and [...]
