David Attenborough warning on climate change, page-329

Here is a bit on CO2

When the Earth was forming there was a lot of CO2 in the atmosphere.


Here's a bit on CO2

CO2) has been present in the atmosphere since the Earth condensed from a ball of hot gases following its formation from the explosion of a huge star about five billion years ago.

At that time the atmosphere was mainly composed of nitrogen, CO2 and water vapour, which seeped through cracks in the solid surface. A very similar composition emerges from volcanic eruptions today.

As the planet cooled further some of the water vapour condensed to form oceans and they dissolved a portion of the CO2 but it was still present in the atmosphere in large amounts.

The first life forms to evolve on Earth were microbes which could survive in this primordial atmosphere but about 2.5 billion years ago, plants developed the ability to photosynthesise, creating glucose and oxygen from CO2 and water in the presence of light from the Sun.

This had a transformative impact on the atmosphere: as life developed CO2 was consumed so that by around 20 million years ago its concentration was down to below 300 molecules in every one million molecules of air or 300 ppm.

Life on Earth has evolved under these conditions

Note that Homo sapiens did not appear until about 200,000 years ago - and atmospheric CO2 has not exceed that concentration until the industrial revolution brought with it massive emissions from the combustion of fossil fuels: coal and oil.