CLIMATE WATCH - Carbon Burps in the Geological Record

"Carbon Burps" ?? What are Carbon Burps?


They are sudden releases of carbon from ancient rocks.

They show up in the geological record as changes in geochemistry (so they are found by using fairly complex laboratory tests on rocks)

They are associated with extinction events, but the scale of extinction varies a lot.



The most extreme geological example of events like this is the end-Permian, when igneous activity broke through coal seams in Siberia.

The interaction of hot magma and coal produced lots of CO2.

The end-Permian event reduced oceanic biodiversity by about 92%.

Recovery of biodiversity took about 10 million years - the fossil record from the next part of geological time, the early Triassic, is very thin.

Messing with planetary systems isn't wise.

One event with possibly closer similarities to what we are doing was about 56 million years ago, the Palaeocene-Eocene Thermal Maximum.

The PETM mechanism (according to some good research) involved volcanic action breaking through carbon-rich sedimentary deposits.

This was related to the rifting that produced the North Atlantic, and we see some of the results of that volcanic activity in eg the Giant's Causeway, Arran, Skye, Mull, Ardnamrchan, Rhum.......




The interaction of hot magma with the sediments produced vast amounts of CO2 - a kind of natural parallel with our activities. But it took many thousands of years.....that's the very dangerous difference this time, the rate of change.

Life will survive, but human societies depend on climatic stability for food supplies - that's the weakest link in all this.




After the PETM, it took around 20 million years for CO2 levels to fall sufficiently for glaciation to begin in Antarctica, at the Eocene-Oligocene transition.

The CO2 was mainly taken up by weathering of the newly-rising Himalayas - when large mountain chains are formed they experience slow chemical weathering and this slowly reduces atmospheric CO2, cooling the Earth.

CO2 in rain makes a weak acid, which causes the chemical weathering.

Rivers carry the carbon compounds down to the oceans, where various processes (such as the formation of calcareous shells by organisms) eventually deposit the material on the ocean floor.

This is the long, slow, part of the carbon cycle.

(Scientific source ......"Terrestrial cooling in Northern Europe during the Eocene–Oligocene transition" - Hrena et al, 2013)

Popular posts from this blog

Climate Change - The link with mass extinctions

Image
What is the worst-case scenario for climate change? The geological record shows that when the atmosphere suddenly changes, there are big effects on living things. Five major  mass extinction  events are recorded in the rock record of the last 600 million years. The biggest extinction was at the end of the  Permian , around 252 million years ago. It is called the  End-Permian mass extinction. Only about 8% of species survived to live on in the Triassic Period. This photo shows geologists investigating tilted sedimentary rocks at Shangsi in South China. Triassic rocks (at the top right) lie over 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 CEs' and some are 'positive CEs'. Negative CEs  indicate that lots of gaseous carbon compounds escaped into the air, causing warming. These are sometime...
Read more

Climate Change - The Greenhouse Effect

Image
What do scientists mean by the " Greenhouse Effect "? When the Sun's energy arrives at the Earth, it travels through the air. Some is reflected back to space, but some hits the Earth and warms it. The warm Earth gives off  infrared radiation  with various wavelengths.   Some of those waves can pass back out of the air to space, but some are absorbed by certain gases in the air. The gases then re-emit the energy into the air. If there are more of those gases, less heat escapes into space. An extreme case has happened on Venus. Concentrated  'greenhouse gases'  on Venus have caused the surface temperature to rise to 735  Kelvin  (462 degrees C; around 900 degrees F) Carbon dioxide levels in the atmosphere have risen quickly  since people began burning large quantities of fossil fuels. There was carbon dioxide in the air before that, at around 270 parts per million. Without any carbon dioxide, the Earth wo...
Read more

Climate Change - Coal and carbon dioxide

Image
Coal, oil and natural gas are  fossil fuels . When they are burned, they  change the Earth's atmosphere. How is that possible?       C oal  is a good example. Coal was formed  hundreds of millions of years ago . Geologists say that a three-metre (10-foot) coal seam took between  12,000 and 60,000 years  to form . Ancient trees and other plants lived, died and were fossilised. All those plants took  carbon dioxide  out of the atmosphere.  Some larger coal seams are, for example, 10 metres thick. They took around  40,000 years to form,  but have been mined and burned in a little over  100 years. The fastest rise of CO 2  in the air seen in   the ice core record (800,000 years)  is  20 ppm in 1000 years. The CO 2  level in the atmosphere is now rising at around  20 ppm per decade . The  carbon  joins up with  oxygen  when it burns. Eac...
Read more