February 8, 2021 By Katie Roundtree

“We forget that the water cycle and the life cycle are one.” — Jacques Yves Cousteau

Water is such a simple element, made up of one oxygen and two hydrogen molecules, but so essential to life. A person can live a month without food, but only about a week without water.  However, water is essential to all life, not just human life.  Here are some interesting facts about water.

There are about 332,500,000 cubic miles of water on earth. That’s about the same amount of water as there was when the Earth was formed! The water from your faucet could contain molecules that dinosaurs drank or walked through! The rocky material that formed Earth contained some water. But that probably doesn’t account for all the water we see today. Comets are mostly water/ ice. It’s possible that comets made regular water deliveries to Earth. It would take a lot of comets to fill the ocean, but comets could well have made a big contribution.

Water covers 70.9 percent of the planet’s surface and is recycled constantly by way of the water cycle.  The water cycle is the continuous movement of water within the Earth and atmosphere. It is a complex system that includes many different processes. Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow. Water in different phases moves through the atmosphere (transportation). Liquid water flows across land (runoff), into the ground (infiltration and percolation), and through the ground (groundwater). Groundwater moves into plants (plant uptake) and evaporates from plants into the atmosphere (transpiration).  On a global basis, evaporation approximately equals precipitation. There is more water in the atmosphere than in all of our rivers combined.  If all of the water vapor in our planet’s atmosphere fell as water at once and spread out evenly, it would only cover the globe with about an inch of water.

Nearly 97 percent of the world’s water is salty, therefore undrinkable. 2.5 percent of the earth’s fresh water is unavailable: locked up in glaciers, polar ice caps, atmosphere, and soil; highly polluted; or lies too far under the earth’s surface to be extracted at an affordable cost.  That leaves just .5 percent for all of humanity’s needs — its agricultural, residential, manufacturing, community, and personal needs.

Water regulates the Earth’s temperature. It also regulates the temperature of the human body, carries nutrients and oxygen to cells, cushions joints, protects organs and tissues, and removes wastes. The human body is comprised mostly water. A newborn baby, for example, is 78 percent water and adults are 55-60 percent water.  The human brain is comprised of about 75 percent water.  Interestingly enough, a tree is also comprised of about 75 percent water.

Usually when solids form, atoms get closer together to form something denser. This is why most solids sink in water. But solid water, or ice, is actually less dense. It expands by about 9 percent, which is unusual. The water molecules form rings when water freezes. All that space makes ice less dense and explains why it floats. This is good because ice floating on top of a body of water lets the rest of it stay liquid. If ice sank, whole oceans could freeze solid!

As you can see, water is essential to life here on earth.  It is important to keep it clean and be mindful of what goes into it.  Water is part of a deeply interconnected system. What we pour on the ground ends up in our water, and what we spew into the sky ends up in our water.  Life on earth simply cannot exist without water. Whether or not it can exist on other planets without water, is a topic for another time….

Sources: www.epa.gov and www.climatekids.nasa.gov.