If the “pale blue dot” that is our planet is this color, it is because of the percentage of its surface that is covered by water. Although Earth has that name, oceans occupy most of the globe. But how much exactly?
The answer is that 71% of the Earth’s surface is covered by water and 96.5% of that amount is in the oceans. The other 3.5% are divided between lakes, rivers, underground reservoirs and even less obvious forms, such as in different physical states: in the ice that covers the poles and mountains and in the steam present in the atmosphere. In addition, a small part of water is also in all forms of life.
How is water divided on the planet
If the vast majority of water on Earth is in the ocean, the small amount of fresh water that remains is largely housed in glaciers and polar ice caps (68.7%) and underground aquifers (30.1%). Rivers and lakes account for only 0.27% of available fresh water and the atmosphere only 0.04% of the total.
If all this water vapor were precipitated at once, it would form a layer only an inch high. Life forms contain about 0.003% of the world’s fresh water, which may seem small, but it is half of the volume available in rivers. It is important to note that all these values are approximate, if added, they will not add up to 100%.
And if the coverage of the oceans today is close to 70%, studies indicate that, in the past, the Earth was already completely covered by them. In the young Earth environment, some of the water in the oceans had its hydrogen and oxygen atoms separated. This allowed some of the hydrogen to escape into space, which ended up, over millions of years, shrinking to a quarter of the mass of the oceans.
In addition, during the ice ages, the oceans were at a level up to 120 meters below the current one, since part of the water was in a solid state, covering the continents.
