[evan_au (OP)]

On social media, I see claims that atmospheric CO2 has steadily reduced over the past 140 Million years, with today's 412 ppm being abnormally low.

I tried searching for information on this, but all I could find were records for <1 million years ago.

So is it an urban myth, or is there some real data around for this time period?

Thanks...

[alancalverd]

It's complete bollocks as far as the last couple of million is concerned, but may well have been true earlier. After all, where did all the coal, oil and sedimentary carbonate rocks come from?

[evan_au (OP)]

Here is one of the posts I saw...

[alancalverd]

Makes sense. And will indeed be important to whatever species inhabit the planet in 500,000 years' time, but right now we have a serious problem of dealing with a short-term fluctuation.

[Petrochemicals]

Carbon dioxide has always been reducing when taken  from the start of life here. Plants took carbon dioxide and turned it into carbon in the fibre and spat out oxygen. To begin with nothing would degrade the tree carcasses (and I imagine to begin with all plant matter) leading to an oxygen rich atmosphere. Bacteria and animals evolved to consume the detritis and oxygen began to dip with co2 normalising.

Personally I would like to see a co2 graph with a margin of error that has been scientifically investigated. Even though mass deforestation farming and drainage occoured at the onset of man's domination it does not appear on graphs to have had much effect.


graph_grid.png (144.29 kB . 1600x800 - viewed 972 times)

If you imagine that England was forested and possessed may bogs 1000 years ago, much like the rest of the world, you would expect some increace at least. I should venture that the methods of measurement do not account for loss over time. The graph above looks very much like all samples before 1850 where taken from the same material

[Bored chemist]

Here is one of the posts I saw...

Who is he and what qualifications does he have?
I'm not saying that is the ultimate arbiter, but it can be a good hint.

[evan_au (OP)]

The graph above looks very much like all samples before 1850 where taken from the same material

Yes, they were taken from the same material - oceans, which cover 70% of the Earth's surface.

But the really rapid increase comes after the year 1900, when cars started to burn petroleum, and home-connected electrical grids started to burn coal.

[Petrochemicals]

The graph above looks very much like all samples before 1850 where taken from the same material

Yes, they were taken from the same material - oceans, which cover 70% of the Earth's surface.

But the really rapid increase comes after the year 1900, when cars started to burn petroleum, and home-connected electrical grids started to burn coal.

But do these samples "age", like wine and metal and tinned food, either loosing material completely, or transmogrifing into othe chemicals? Surely there should be a substantial spike in co2 as the CO2  in cleared forests and bogs entered the atmosphere. Forest and wetland drainage has probably released as much co2  as man's use of fossil fuels.