Our planet, despite being called LandIt has a high percentage of water, but what exactly? The truth is that it is often said that the Earth is made up of three-quarters of water but What is the exact percentage of water on Earth?. We reveal it below.
What percentage of water does the Earth have?
H2O, water, something that is so common but at the same time so necessary, is present everywhere on our beloved planet Earth: seas, oceans, groundwater and aquifers, glaciers and polar caps, rivers and streams, thus covering three-quarters of the earth’s surface or what is the same: more than 70% of our planet is water and if we pass it to kilometers, the data is also surprising, since water (mainly oceans), it covers 361 million of the 510 million km 2 of the earth’s surface.
The origin of water on Earth
The amount of water has not increased since it first appeared on Earth about 3.4 billion years ago. Originally, when it formed, Earth was a barren, waterless planet.
However, approximately 10 million stars, asteroids and comets fell to Earth in the period between 50 and 100 million years after its formation.
It was about Kuiper belt celestial bodies or the Oort cloud with a diameter generally less than 20 km and composed in 80% ice water. These asteroids, filled with water and ice, were enough to bring water to Earth.
There is however, a debate on the origin of the presence of water in gaseous form in the atmosphere. The hypothesis currently preferred by researchers refers to the carbonaceous chondrites that carry water and that reached Earth at the end of the planet’s growth.
The water would not come from space
The second hypothesis is that of comets. However, according to the Woods Hole Oceanogaphic Institution, this assumption is incorrect. This research center discovered that water from Earth and water from meteorites formed before Earth shared the same composition isotopic hydrogen. So it was deduced that the water would not have been brought to Earth by wet comets, but that would have been present since its formation.
Finally, according to the degassing theory, the water would have been present in gaseous form in the various envelopes of the Earth since the creation of our planet, 4.5 billion years ago.
However, half of the water infiltrates the rocky mantle where it still exists, and the other half is on the surface. This water gave rise to plate tectonics, which made the rocky mantle mobile. This had a great impact on the evolution of life on Earth.
Today therefore, most of our fresh water is found under our feet in aquifers of different depths. These aquifers, fed by precipitation through infiltration into rocks, gravels or porous sands, are being used more and more.
Where is the water on Earth?
The Most important water reserves are, of course, the oceans and seas, with 1,320 million km 3.
Then there are some 24 million km 3 in the polar caps (Greenland and Antarctica), glaciers and eternal snows.
So, almost the same amount of water rests in the subsoil and in the earth’s crust. The other water reserves are in descending order:
- permafrost ice;
- the lakes ;
- soil moisture;
- humidity of the atmosphere;
- water courses: in the world there are around 250 international water tables or rivers that are potential sources of diplomatic tensions, especially in a context of scarcity of this resource;
- green water, that is, all the water contained in the biomass. What is called green water is all the water that plants and living organisms contain. Green water represents 2/3 of all water resources on Earth, divided into three categories of use: agriculture (86%), industry (9%) and domestic water (6%). This water trapped by living organisms is essential for life: it is estimated that living beings on Earth contain a little more than 1,100 km 3 of this biological water.
Water in liquid form is the state in which water is found in the highest proportion on earth, 97.842% of the total volume, but we can also establish the different percentages of how the presence of water is divided on our planet.
- 1.320.000.000 km 3 of salt water (97.2% of the total) is found in the oceans.
- 25.000.000 km 3 (1.8%) are found in glaciers and polar caps.
- 13.000.000 km 3 (0.9%) are groundwater.
- 250.000 km 3 (0.02%) of fresh water from lakes, inland seas and rivers .
Finally note that In the atmosphere there is a huge mass of 12,900 km³ of water. Only 2% of these 12,900 km³ of water present in the atmosphere exists in condensed form (clouds); the rest is diffuse, present in the form of water vapor. The percentage of water vapor in the atmosphere is low: 0 to 4% of its composition. The whole represents only 0.001% of the planet’s water.