Water is the main component of all known life forms. Only habitable areas of the Cosmos are those capable of housing water in a liquid state. Each molecule of water is composed of two atoms of hydrogen and one of oxygen, two of the most common elements that exist.
The vastness of the Cosmos contains a lot of water. It is frozen in comets, exoplanets, or on moons of the Solar System such as Europa and Enceladus. Also in the form of steam, in the immense clouds of interstellar gas. Water is formed in the same reactions that originate the stars. When a star explodes, it releases into space all that water in the form of steam.
But, so far, the Earth is the only known place that contains water in a liquid state. For 3,900 million years, the Earth's water flows in a cycle that sustains each and every living being.
When we say that three quarters of the Earth is water we mean the oceans, rivers, polar ice, glaciers, the water vapor of the atmosphere ... But the largest water reservoir on Earth is inside. The upper part of the earth's mantle stores a quantity of water ten times greater than the sum of all the oceans. It is in the form of steam, and is released in small quantities through volcanic eruptions, cracks and underwater chimneys. The Earth also loses part of its water, which escapes into space through the upper layers of the atmosphere.
The amount of life that the planet can maintain depends on the amount of liquid water available. And that amount is limited. It is constantly renewed through the water cycle. Thus, the water of the oceans evaporates and passes into the atmosphere. Winds distribute clouds and water vapor throughout the planet. When it condenses, it falls in the form of rain, or snow, hail ... Living beings use it to survive, and return it to nature in the form of waste or when they die.
Since a drop of water leaves the ocean until it returns to it, thousands of years go by. Meanwhile, it is part of many living beings. The water that today forms part of our body, was previously part of other human beings, and of many living beings. Before, he left the ocean and, someday, will return to him.
The balance of water in its different states, liquid, solid and gas, stabilized the Earth's temperature and prepared it for life. Ice weighs less than liquid water, floats and creates a layer that prevents heat from escaping from the water underneath. Marine currents regulate the temperature of the planet. That's why the oceans don't freeze.
Global warming is breaking the natural balance between ice and liquid water. Polar ice melts and emits tons of very cold water into the sea that goes to the bottom and cools the oceans. Marine currents can vary and affect the climate of the entire planet.
Water made life possible, because life began in the water and evolved to conquer the earth. It is the source of life of all living beings. It is up to us not to destroy the fragile balance that sustains us.
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