I came across this image a number of months ago while looking through the USGS website. It resonated with my visually oriented brain, and with other information I’ve read about regarding the volume of accessible fresh water on the planet. It is frighteningly little. Images taken from space represent our planet as having beautiful blue water covering about 70 percent of the surface. It is deceptive though. The oceans, at their deepest, are only a few miles deep, which amounts to an insignificant water volume when one considers that there is another 4,000 miles to the core of the planet. The planet is about 8,000 miles in diameter, while the average depth of the ocean is only about 2.65 miles (14,000ft). It is simply a very thin water membrane.
The website: http://ga.water.usgs.gov/edu/earthhowmuch.html provides much more information, but my quick summary will tell you that the largest of the three spheres represents all the water on earth. It would include the oceans (which captures 96.5% of all the water), the ground and atmospheric water, and all the water in lakes, rivers, and streams. The middle sphere represents all of the liquid freshwater available on the planet. Note that 99% of that freshwater is in underground rivers, aquifers, and the like. It is, for the most part, not easily accessible. Finally, the very small blue sphere over Atlanta, Georgia, represents the volume of accessible freshwater that is essential for life to humans and millions of other species throughout the world. The diameter of this sphere of water is only 34.9 miles. Amazingly small, considering its enormous importance to most living things on the planet.
Looking at the oceans, and the thousands of lakes and rivers throughout the world, it would seem that there is an endless supply. In the Midwest and East of the US, rich vegetation and frequent rain storms reinforce this notion. However, that is not the case of much of the rest of the world. Many people have argued that the wars of the future will be about water. http://www.aljazeera.com/indepth/features/2011/06/2011622193147231653.html Global climate change exacerbates the issue by increasing the intensity of the droughts, and by creating less frequent, but stronger storms that generate extreme water events whereby most of the water that falls from the sky runs off, and away from the crops that need moisture deep into the soil. (Slow steady rains are better than gushers)
Be aware. Take personal and professional responsibility for a sustainable healthy future.