Water

Where is all of the world's water going?  You would think that in a closed system, such as the global climate system of water evaporation and precipitation, there would be a set point of available water.  But we are seeing that is not the case.  Droughts are occurring globally.  Glaciers are melting, the sea level is rising.  The rising of the sea level will cause a contamination of fresh water sources, causing that water to be unusable by humans and wildlife.   The increase in surface area to the oceans will cause a warming of the oceans, further fueling wild and chaotic weather patterns - more hurricanes, more typhoons, bigger hurricanes, a longer hurricane season, etc.  The reduced salinity, caused by the influx of freshwater into the salty ocean water, will affect biodiversity, culminating in an increase in algae blooms and to the death of barrier reefs.

Already deep aquifers are running dry globally.  The human population obtains about 30% of it's water through these deep underground aquifers.  These depleted aquifers will create unstable ground, further increasing the number of sinkholes.

As the planet is forced to house an exponential increase in human population these needs will be greater, and yet, the availability of water will decrease.  Already lakes and rivers are experiencing record amounts of dryout, meaning our topographical sources of water are literally disappearing, mostly from overuse.  Water in the form of rain or snowfall does not fall equally around the globe.  As the climate continues to warm up we will see the wet areas get wetter and the dry areas become dryer.  California and the western United States will not recover from the drought that had befallen them.  The sheer feat of moving water from areas of abundance to areas of drought are both cost prohibitive and would create an even greater impact to global warming in the form of carbon emissions, not to mention the ecological impact such a transference would cause.

What does this mean?  This means less agriculture.  This means a decrease in the ability to feed our growing populations.  This means a substantial rise in the prices of food.  The large-scale agribusiness model of food production will slow down, because there will not be water available to sustain it.  There will be less stable land available for urban development, nor will there be enough water to support such urban endeavors.