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Future Drought

Examination of data from many diverse sources shows that the world is warming. According to global climate models, this will have a significant impact on the hydrologic cycle and, consequently, on the nature of drought in the future.

The hydrologic cycle describes the movement of water between the oceans, land, and atmosphere. Two important factors are relevant: (1) warmer air can hold more water vapor (moisture), and (2) warmer air causes more evaporation (or evapotranspiration which includes water used by plants). As the world continues to warm, the air will hold more moisture and more water will be evaporated, so there will be an increase in heavy rain events producing more frequent flooding. But more evaporation with hotter temperatures will dry out the soils more and increase water demand, which is one component in the water demand versus water supply drought equation. More demand translates to more frequent and intense droughts.

So, in this climate warming scenario, an accelerated hydrologic cycle will result in more severe droughts (especially in the summer) interspersed with periods of intense flooding. This one-two — dry-wet — punch will add extra stress to our agricultural and economic systems.