The study of the effects of the climate system on the hydrologic cycle over time and space, both globally and locally. Changes in the relationship between the climate system and the hydrologic cycle underlie floods, drought, and possible future influences of global warming on water resources. See M. L. Shelton (2009). Simultaneous variations in weather and climate over widely separated regions are commonly known as hydroclimatic teleconnections (Kashida et al. (2010) J. Hydrol. 395, 23).