18.2 Origin of the Atmosphere Some people credit the marvelous uniqueness and design of Earth's atmosphere to pure chance. To them, our amazing atmosphere is just one big coincidence. Do you remember their view of Earth's beginnings from Chapter 5?
The Old-Earth Story
According to old-earth scientists, the earth began forming more than 4.5 billion years ago. The early earth was a smaller, molten ball covered by a thin crust. Within several hundred million years of the planet's birth, a moon-forming collision occurred and melted the entire earth again. As the earth cooled from this collision, gaseous materials gathered into an atmosphere. That atmosphere was hot and contained mainly the light gases hydrogen and helium, which on their own cannot support life. No free oxygen was present. The emissions of numerous volcanoes changed the atmosphere. Water vapor together with carbon and nitrogen compounds began to collect in the atmosphere. Ice from comet bombardments added water and other compounds to the oceans and atmosphere. Sometime during the first billion years of Earth's existence, evolutionists believe that life appeared from non-life. These life forms were anaerobic bacteria that could live in the absence of oxygen. Biochemists believe that oxygen would have destroyed the complex molecules needed to build even the simplest cell. Even so, ultraviolet light from the sun broke down some water vapor into oxygen and hydrogen. This oxygen quickly reacted with minerals in the rocks, so the simple bacteria were not harmed. Oxygen levels were probably less than I% of today's levels. But along the way, oxygen-producing organisms called cyanobacteria evolved. Around 2.4 billion years ago, the surface rocks had reacted with as much oxygen as they could, so the extra oxygen entered the atmosphere, and the oxygen levels in the air jumped. This oxygen catastrophe killed off most of the anaerobic organisms, and paved the way for more advanced forms of life to evolve. Secular scientists believe photosynthetic organisms are responsible for the modem oxygen-rich atmosphere we have today.
The Young-Earth Story
A biblical young-earth view of the atmosphere's origin is much simpler. To be completely honest, we don't know when God created the atmosphere because it is not mentioned in the Creation story in the Bible. We can assume that when God formed the firmament (or great expanse) between the waters above and the waters below on Day 2 (Gen. 1:6-8), He also created the atmosphere in preparation for the creation of plants on Day 3. Plants needed atmospheric carbon dioxide and water vapor to live, and all the other creatures and humans definitely needed to breathe during the remaining three days of the Creation week. God made the atmosphere "very good," along with the rest of His creation. Even the Fall probably didn't noticeably change the atmosphere very much. But the Flood did. Volcanic activity and changes in the sizes and shapes of the oceans deeply affected the earth's atmosphere. We can still see the effects of these changes today in the atmospheric chemistry, weather patterns, and climate zones all over the world. But though God judged our world, it still bears signs of His design and loving care. The atmosphere is one grand exhibit of this.