Effects throughout the world

There will be an increased general awareness throughout society of the need to conserve water (8, 12).  This is the single most likely outcome of the prediction.  This is happening already as our population continues to expand and our water resources are becoming more and more stretched.  People are becoming aware of the problem as water restrictions are becoming more common and widespread (10, 11) and the news media continue to stress the issue.

If a country can't irrigate the land to grow its own food, it will import food instead (1).  This effect is also already being observed throughout the world.  To an extent this may be good, since it provides a market for countries with a surplus and encourages better distribution of resources throughout the world.  However, the economic consequences that can result from relying on other countries for one's food can be unpredictable.

Environmental degradation will occur from the shrinkage of lakes and rivers.  This has already occurred, as evidenced by the many rivers in the world that barely reach the sea (1).  Of course, under our present government, we see that environmental regulations prevent water and energy providers from tapping into much water that could potentially be used, because of other (mostly environmental) problems associated with water collection (12).  This is certainly much more the case in some parts of the world than others at present (6), and there is no telling how long governments which attempt to protect the environment--a recent development, historically speaking--will persist.

Recreational possibilities will be reduced as lakes and rivers shrink (5).  This may seem like relatively minor difficulty for some, but it can affect such things as tourism in countries that are known for their waterways.

Local effects (for the western United States)

Water regulations will occur more frequently, requiring people to change their lifestyles for lower water usage (10).  People may become less interested in leisure activities such as gardening and golf that require a lot of water.

A shift to more unirrigated crops such as wheat is likely in areas where irrigated crops are now grown (9).  High value crops will also be grown more to maximize the amount of profit per unit area (2, 9).

As farmers are faced with more and more expenses concerning how to maintain irrigation equipment and use water efficiently, and for other reasons, some farmers will eventually encounter financial hardships (12).  This has been occurring already for some time.

Other possible effects*:

A society cannot go on forever without food.  If urban societies continue hoarding water while agriculture declines, where will our food come from?  This can only go on so long before either the urban society dies of starvation, or something else gives.

Throughout history we see that a precarious balance is kept between the power and control exerted by the urban societies and the servitude and relative weakness of the farmers (1).  However, if this situation continues to be carried to more and more of an extreme, say, in the United States, a relatively sudden collapse of the urban society could potentially occur.  Of course, many other factors would no doubt be involved in such an occurrence.  But it is possible that sometime in the future, a reversion to smaller farms and a higher proportion of the population returning to the farming community might occur.

Alternatively, biotechnological and other advances may be able to keep us ahead of the water game much longer than we expect.  Already we see crops being developed that are able to produce a higher yield with less water use than conventional crops (12).  So there may be no major dramatic change in the near future for this reason (5), but it is too early to tell to what extent this scenario is playing out.  But it would seem that any effects on humanity resulting from this possibility would be less remarkable.

In any case, there are numerous ways in which the change in water use from agriculture to urban use will affect humanity.  Only time will tell which of these occurrences will be the most important to the future of humanity.  Most people agree that the most prudent thing to do is to exercise care and responsibility in how we use all of our water, no matter what our position in society--preparing for the worst, but hoping for the best, and working to make our future as close to "the best" as possible.

*These effects are more speculative, and the conclusions based largely on the reasoning of the author.