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

Because it is a effect of climate change and weather patterns that have been altered, increased pollution, and the over use of water, so as long as these things keep happening there will be water shortages,

Explanation:

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:

Due to changing climatic conditions

Explanation:

The climate has become unpredictable these days. This has disrupted the hydro-logical cycle due to which rain pattern has varied a lot. Now some geographical regions receives excessive rainfall which ultimately leads to floods and some regions receives scarce rainfall which ultimately face drought.

The extreme climatic concerns such as global warming arising due to pollution are leading to melting of fresh water reserves in glaciers. This glacier water reaching the oceans is increasing the level of oceans every year by a few millimeters. With increasing undulations in the pattern of climate, not much effective measures have been taken to preserve and restore fresh water.  

Water scarcity has been recently reported in the Cape Town city of South Africa.  

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!