A few days ago, we wrote about a remarkable graphic released by the USGS, showing all the water on Earth---freshwater, saltwater, water vapor, water in plants and animals; all of it---rolled into a sphere. That sphere was only 860 miles in diameter, fitting comfortably between Salt Lake City and Topeka, Kansas, on a map. It was striking, especially considering that the water available for humans use in our daily lives is only a very small fraction of that; the vast majority of the Earth's water is saltwater, and most of the freshwater is tied up in glaciers. How big would a sphere of just the freshwater available to humans be? Reader Jay Kimball of 8020Vision, his interest piqued, went ahead and made such a graphic:
That sphere---the sphere representing the freshwater available to humans---has a diameter of just 170 miles. Head to his blog to see the math
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