I think that much more than energy crises, we should worry about water shortages. Even though most modern societies depend on energy, people can and do live without it. No on can live without water.

The water situation is beginning to look grim. Just a brief search on global water shortage comes up with tons of stuff:
http://www.usatoday.com/news/nation...ater-usat_x.htm
http://ag.arizona.edu/AZWATER/awr/dec99/Feature2.htm
http://whyfiles.org/131fresh_water/
http://moneycentral.msn.com/content/P102152.asp
http://www.worldhungeryear.org/why_...&style=ws_table
http://www.actionbioscience.org/environment/kassas.html
http://www.cela.ca/faq/cltn_detail.shtml?x=1508

Besides just plain old using up water faster than it's being replaced, there are climate changes helping the problem along. One of these is a widespread desertification:
http://pubs.usgs.gov/gip/deserts/desertification/
http://www.unccd.int/

Last summer I spend 5 weeks in Montana at a geology field camp, working with some very very smart professors who work in geological sciences. From the work they do, they all seem to think that water shortage will be a huge issue, and one that not many people right now are aware of.