70% of the Earth's surface is water and only 30% is land.
We have a planet covered in a very thin film of water. To give us an idea: if we wet an orange, the layer that remains on the peel is equal to the proportion that exists on Earth. No, ours is not a water planet, it is just a wet planet.
However, that time Water It is what has made life possible. Furthermore, most of the water on Earth is salty: 97.5% is water from seas and oceans. The remaining 2.5% is fresh water, but almost all of it is frozen at the poles and in glaciers. Of fresh water, 69.7% is frozen water, 30% is underground and in rivers and lakes there is only 0.3%.
If the planet had 100 liters of water, there would only be 750 milliliters of groundwater and 7 milliliters in surface rivers and lakes; the equivalent of three glasses would be all the fresh water for terrestrial life and humanity. Whose is the water? Of humanity? Some say that the first owner of water should be the one who produces it: nature.
- In the oceans and seas: 1,370,000,000 km3
- In the earth's crust: 60,000,000 km3
- In the glaciers and perpetual snow: 29,170,000 km3
- In the lakes: 750,000 km3
- In soil moisture: 65,000 km3
- In atmospheric steam: 14,000 km3
- In rivers: 1,000 km3
Due to the fact that the waters are in constant movement (they evaporate, condense, infiltrate, are dragged by rivers to the sea or the ice at the poles breaks, migrate, melt), it is convenient to consider that the figures presented above have a margin of error of 10 to 15%. For example, in terms of evaporation alone, 449,000 km3 per year go into the atmosphere from the oceans.
The world has 12,500 to 14,000 million cubic meters of water per year for human use. This represents about 9,000 cubic meters per person per year, as estimated in 1989. It is estimated that by 2025 the global availability of fresh water per capita will fall to 5,100 cubic meters per person per year, as another 2,000 billion inhabitants will be added. to the world's population. Even then, this amount would be enough to satisfy human needs as long as the water was distributed equally among all the inhabitants of the world. Against this background, the need to generate strategies to promote awareness of the use and water conservation it becomes a priority and common to all human beings.
For more information about water on the planet you can review the following materials or consult our Thematic Library, the section Water in the world.