Monday, 22 December 2014

Mass Extinction and the link to atmospheric carbon

Geologists have discovered five major mass extinction events in the rock record of the last 600 million years.
The extinction at the end of the Permian period, around 252 million years ago, was the most extreme.

It is called the End-Permian mass extinction.


Only about 8% of species survived to live on in the Triassic Period.



This photo shows tilted sedimentary rocks at Shangsi in South China, with Triassic rocks at the top right overlying the older Permian rocks.

Each mass extinction in the rocks matches with a change in the chemistry of the rocks called a 'carbon excursion'.

Some of the carbon excursions are 'negative' and some are 'positive'.

Negative CEs involve lots of gaseous carbon compounds adding to the air, causing warming.

Positive CEs involve the reverse.... processes absorb the gases and cooling follows.

Examples of positive CEs include 

The 'Snowball Earth' events.



An example of a negative CE is 

the Palaeocene-Eocene Thermal Maximum.



Ecosystems recovered from the PETM ..... it 'only' took 100,000 years.

In the PETM link above, see Section 9 ..Conclusions... last sentence.....

"the PETM is a natural analogue for increases in atmospheric COdue to fossil fuel burning over the next century, and implies a relatively high climate sensitivity."


The earth systems simply react to the chemistry ..... how the gases get into the air is unimportant.
And currently CO2 is rising at 20 ppm per decade.


Nothing like this has happened in the time of Homo sapiens.

Uncontrolled addition of CO2 is dangerous and will have serious consequences.




Photographs of ice core drilling

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