Our Earth has a lot on water on it, or so you may think!
About 70% of the Earth's surface is covered by water. So it would seem the Earth is a watery planet. We must have plenty of water.....right? Maybe not.....
We need to look at the volume of water on Earth. It's difficult to calculate with certainty but there is about 1.38 billion (1,380,000,000) cubic Km of water on Earth.
This water is in our seas, lakes, and rivers, but also frozen in glaciers and ice caps, underground, in swamps and in the atmosphere.
The volume of the Earth is about 1,083,210,000,000 km3
The fraction of the Earth's volume taken up by water is:
1,380,000,000 ÷ 1,083,210,000,000
= 0.00127 or 0.127%
So 70% of the Earth's surface is water, but only 0.127% of the Earth is water.
Surprising isn't it?
There's more..
Most of Earth's water is saline (salt water in the oceans) only about 2.5 to 3 % of the total water is fresh water, roughly 35 Million km3. Seems alot?
Well not all of this is easily available to us, alot is frozen or underground.
Our lakes and rivers probably account for less than 0.4% of all fresh water, about 140,000 km3, or 140,000,000,000,000,000 litres, 140 Quadrillion litres! Enough to fill 56 billion Olympic size swimming pools!
Surely this is still alot? Perhaps not. Read on and then go to our quiz page.