Fossil fuel formation linked to rise in atmosphere’s oxygen

The rapid rise in the atmospheres oxygen roughly 500 million years ago which made advanced animal life possible on Earth is linked to the process that led to the formation of fossil fuels, suggests new research.

According to the study, the rise in oxygen was associated with a rapid increase in the burial of sediment containing large amounts of carbon-rich organic matter – the raw material of coal, oil and natural gas.

Background:

Multicellular life is largely a creation of the “Cambrian explosion,” which coincided with a spike in atmospheric oxygen roughly 500 million years ago. It was during the Cambrian explosion that most of the animals appeared and evolved.

What accounted for the sudden spike in oxygen during the Cambrian?

The study linked the rise in oxygen to a rapid increase in the burial of sediment containing large amounts of carbon-rich organic matter.

• The key is to recognise that sediment storage blocks the oxidation of carbon. Without burial, this oxidation reaction causes dead plant material on Earth’s surface to burn.
• That causes the carbon it contains, which originated in the atmosphere, to bond with oxygen to form carbon dioxide. And for oxygen to build up in our atmosphere, plant organic matter must be protected from oxidation.
• And that is exactly what happens when organic matter — the raw material of coal, oil and natural gas — is buried through geologic processes.

Concern expressed by scientists:

The researchers warned that today, burning billions of tonnes of stored carbon in fossil fuels is removing large amounts of oxygen from the atmosphere, reversing the pattern that drove the rise in oxygen. And so the oxygen level in the atmosphere falls as the concentration of carbon dioxide rises.