Natural Cycles for Life
Natural Cycles for Life
If a city’s supply of fresh air and water were cut and its sewers blocked, disease and death would soon follow. But consider: Our planet is not like a restaurant, where new food and supplies are shipped in from outside and garbage is carted away. The clean air and water we depend on are not shipped in from outer space, nor is waste matter rocketed out. So how does the earth remain healthy and habitable? The answer: the natural cycles, such as water, carbon, oxygen, and nitrogen cycles, explained here and shown simplified.
The water cycle: Water is essential to life. None of us can live without it for more than a few days. The water cycle distributes fresh, clean water around the planet. It involves three stages. (1) Solar power lifts water into the atmosphere by evaporation. (2) Condensation of this purified water produces clouds. (3) Clouds, in turn, form rain, hail, sleet, or snow, which falls to the ground, ready to evaporate again, thus completing the cycle. How much water is recycled annually? According to estimates, enough to cover the earth’s surface uniformly to a depth of more than two and a half feet (80 cm).4
The carbon and oxygen cycles: As you know, in order to live you need to breathe, to take in oxygen and give out carbon dioxide. But with countless billions of humans and animals doing the same thing, why does our atmosphere never run out of oxygen and become overloaded with carbon dioxide? The answer lies in the oxygen cycle. (1) In an amazing process called photosynthesis, plants take in the carbon dioxide that we exhale, using it and the energy from sunlight to produce carbohydrates and oxygen. (2) When we take in oxygen, we complete that cycle. All this production of vegetation and breathable air happens cleanly, efficiently, and quietly.
The nitrogen cycle: Life on earth also depends on the production of such organic molecules as proteins. (A) To produce those molecules, nitrogen is needed. Happily, that gas makes up about 78 percent of our atmosphere. Lightning converts nitrogen into compounds that plants can absorb. (B) Then plants incorporate those compounds into organic molecules. Animals that eat those plants thus also acquire nitrogen. (C) Finally, when plants and animals die, the nitrogen compounds in them are broken down by bacteria. That process of decay releases nitrogen back into the soil and atmosphere, completing the cycle.
Perfect Recycling!
Humans, with all their advanced technology, create countless tons of unrecyclable toxic waste annually. Yet, the earth recycles all its wastes perfectly, using ingenious chemical engineering.
How do you think the earth’s recycling systems arose? “If the Earth’s ecosystem had truly evolved by chance alone, it wouldn’t possibly have been able to reach such a perfect level of environmental harmony,” says religion and science writer M. A. Corey.5 Do you agree with his conclusion?
Teeming With Life
No one knows how many species there are on earth. Estimates vary from 2 million to 100 million.6 How pervasive is life on our planet?
Earth: Just one hundred grams (3.5 ounces) of soil has been found to host 10,000 species of bacteria,7 not to mention the total number of microbes. Some species have been found almost two miles (3 km) underground!8
Air: In addition to the birds, bats, and insects that fly through the air, the atmosphere is filled with pollen and other spores, as well as seeds and—in certain areas—thousands of different kinds of microbes. The diversity of microbial life in the air is “on par with the diversity of microbes in the soil,” says Scientific American magazine.9
Water: The oceans remain largely a mystery because in order to study the watery deep, scientists often have to use costly technology. Even coral reefs, which are relatively accessible and are well-surveyed, may host millions of yet unknown species.
Did this impressive variety of life arise by chance? Many would agree with the poet who wrote: “How many your works are, O Jehovah! All of them in wisdom you have made. The earth is full of your productions.” *—Psalm 104:24.