Friday, June 1, 2012

Water on Earth

How much water is there on Earth?

We often hear people say 70% of the Earth's surface is covered by water. Oceans and seas constitute the largest amount of water, roughly 96.5%. The rest exists in lakes, rivers, underground water sources, in our body, and in your pet.

That does sound a lot isn't it? In reality, it's really not that much.
The blue spheres in the picture above show the relative amount of Earth's water in comparison to the size of the Earth. Surprisingly small isn't it? But we have to remember that water spreads evenly over the entire planet forming a thin layer of liquid, and that's how the little blobs colour our Earth blue.

Let's start with the smallest blob, the one hanging above the state of Georgia. It represents the surface-fresh water sources in all the lakes and rivers on the planet, i.e. the water that we use everyday. The diameter of this sphere is about 56.2km, and the volume of this sphere is about 93,113 km3.

The intermediate sphere, above Kentucky, shows the Earth's liquid fresh water in groundwater, swamp water, rivers, and lakes. We get our fresh water from rivers and lakes, but underground water sources are most of the time unavailable. This sphere has a 272.8 km diameter, and a volume of 10,633,450 km3.

The largest blue sphere represents all the water on Earth-seas, oceans, lakes, rivers, underground water. That sphere has a radius of 1385 km, and the volume would be 1.386 billion km3.
So when you compare the amount of water that can be used to the amount of water that cannot be used, the percentage is pathetically meagre-only 0.0067% of the water on Earth is reachable and usable by humans and land animals. What's worst, a large amount of that water is heavily polluted especially those in congested cities in India and China, rendering them essentially unusable.
Unfortunately there are still intellectually-retarded rich capitalistic buffoons somewhere who love to stand (or sit?) for hours on end in their showers and waste clean water needlessly while they imbibe in their sordid fantasy.

But to think on the positive side, it's amazing so many water-carrying asteroids actually hit the Earth during its infancy to result in that much water on Earth today.


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