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Think about it.
Marcelo Camelo's profile photoChuck Dahmer's profile photoDavid Schmidt's profile photoChristopher Carr's profile photo
If all the Earth's water was put into a single sphere everyone would die.
Reasonably smooth. From the bottom of the Mariana Trench to the top of the Everest, it's 0.3% of the radius of the Earth. Equivalent to a half millimeter bump on the surface of a pebble 2cm in diameter.
If spread evenly over the surface of earth, the resulting ocean would be 2.7km deep.
Considering that the tiny drop of water was non-existent 4.5 billion years ago, we've come a long way. Even more amazing is what we can do to increase earth's water volume: hydrocarbon combustion.
+Chuck Dahmer, insightful observations. Also lot's of room for improvement in term of water resources management (fresh water, which is less than 4% of that blue drop).
I agree, +Marcelo Camelo. Most people are stuck in the idea that water must come out of the ground, thus all the calamity associated with running out of water. However, like all matter and energy, we cannot run out of water. We just change its form and location.

People are usually surprised when reminded that water is just hydrogen and oxygen, neither of which are particularly hard to come by, especially considering how hydrocarbons fit in the cycle. Furthermore, rather than just devoting so much effort to limiting our use, I'm of the opinion we should dedicate more toward a quicker recovery of the water we do use.

For example: Why do we waste so much effort at flushing sewage through vast underground transport systems to a central location for processing when it's entirely possible to process household waste in situ?
That said, it's been noted recently that there are pretty darn large untapped aquifers in sub-Saharan Africa -- which is a good the short-term, at least.
What the article doesn't say is, that 860 miles in diameter is higher than ISS currently orbiting around the Earth. Actually it's more than three times the distance. Although the sphere looks rather small compared to the size of the Earth, imagine how big it'd be next time ISS flies by.
LEO is very LEO. :-)

Great to have all these perspectives, as these scales aren't intuitive.
As with most human primates, I'm much better with trees and mountains than I am with space stations.
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