The Liquid of Life

WATER is an enigma. It is both simple and complex. Each molecule comprises just three atoms—two of hydrogen and one of oxygen. Yet, scientists still do not fully understand how water molecules work. What we all know, though, is that water is essential to life, making up about 80 percent by weight of all living things. Consider just five attributes of this amazing substance.

1. Water can store a lot of heat without a substantial rise in temperature, thus helping to moderate climate.

2. Water expands when it freezes, causing ice to float and form an insulating layer. If, like other substances, water became more dense as it froze, the lakes, the rivers, and the seas would solidify from the bottom up, entombing everything in ice!

3. Water is highly transparent, enabling light-dependent organisms to survive at considerable depths.

4. Water molecules produce surface tension, creating an elastic “skin.” This tension enables insects to scamper about on a pond, causes water to form into droplets, and contributes to the capillary effect, which helps water to hydrate the tallest plants.

5. Water is the most efficient solvent known. It is able to carry in solution oxygen, carbon dioxide, salts, minerals, and many other vital substances.
Essential to Earth’s “Air Conditioner”

Oceans cover about 70 percent of the earth, giving them a major role in climate control. Indeed, oceans and atmosphere are practically one, constantly exchanging heat, water, gases, and momentum in the form of wind and waves. They also work together carrying solar heat away from the Tropics toward the poles, thus moderating global temperatures. In fact, for most organisms to survive, temperatures must stay within the range that allows water to remain a liquid. “It appears that Earth got it just right,” says the book Rare Earth—Why Complex Life Is Uncommon in the Universe.

This article originally appeared in the February, 2009 article of Awake!. Read it online »