Explain why water shortages are expected to be such a widespread problem in the future

Water scarcity is the lack of sufficient available water resources to meet water needs within a region. It affects every continent and around 2.8 billion people around the world at least one month out of every year. More than 1.2 billion people lack access to clean drinking water.[1]

Water scarcity involves water shortage, water stress or deficits, and water crisis. The relatively new concept of water stress is difficulty in obtaining sources of fresh water for use during a period of time; it may result in further depletion and deterioration of available water resources.[2] Water shortages may be caused by climate change, such as altered weather-patterns (including droughts or floods), increased pollution, and increased human demand and overuse of water.[3] The termwater crisis labels a situation where the available potable, unpolluted water within a region is less than that region's demand.[4]Two converging phenomena drive water scarcity: growing freshwater use and depletion of usable freshwater resources.[5]

Water scarcity can result from two mechanisms: