How Our Earth Came To Be

The first segment of the three-part global climate change presentation is about the origin and evolution of the earth-climate system. This is one of the most intriguing aspects of our atmosphere because--as the presentation states--it has not always been inhabitable.

Before getting into the theology of our planet, let's briefly summarize how our modern atmosphere came to be. When Earth began, it was literally just a rock in space with a thin atmosphere devoid of oxygen and water (most of the hydrogen and helium was lost due to solar radiation). Scientists say that, over millions of years, frequent seismic activity caused a mass outgassing from volcanoes, which primarily spew H20. With water vapor being introduced into the atmosphere, weather started occurring; over billions of years, the oceans were formed as more and more water was added to and precipitated out of the atmosphere. Once the oceans were formed, life sparked. Photosynthetic organisms evolved in the oceans and started emitting oxygen! Early on, life was still unable to exist on land, as the direct UV radiation from the sun was still too strong for species to survive. However, as the plant-emitted oxygen reached the stratosphere, the molecules were torn apart by the UV and came back together in the form of ozone, thus forming the protective ozone layer!  Finally, life was able to evolve on land and the rest is history.