In response to a comment by a Donald L. Klipstein on WUWT:
The earth’s climate has not been stable in the past 500 million years. What has happened shows signs that the climate has non-constant stability….
I felt I had to counter the assumption that just because the climate shows variability, that this somehow infers that the climate itself is unstable. There are two potential causes of long term variability that could explain such large changes as seen below:
Biological Evolution
The single biggest driver of long-term climate change is probably changes to plant biology as demonstrated by the carboniferous when the evolution of plants with lignin (shown above as “1st CO2 desert). The effect of this small change was that the hydrocarbons in plant cells could not be broken down by the then fungi. The result was that they tended to accumulate rather than decompose and as a result carbon was locked up in the geology creating the first “CO desert” – which might have ended in the ultimate destruction of earth – except for the evolution of fungi that could digest lignin.
The second “collapse” appear to coincide with the emergence of flowering plants and grasses, however it is difficult to see what biological process might be “sucking” the atmosphere “dry” of CO2. However, one possibility is that the large areas of moss are somehow locking up CO2 in peat. However as the primary cause of these peat areas is moss – a plant species that has been around for a very long time, it is difficult to understand why this would be “the change” that caused the second CO2 desert.
Geological feedbacks
However, the main thing I wanted to counter is that apparent feedback in the “climatic temperature” shows any form of feedback mechanism in the climate. Because temperature may just be an indicator of feedback mechanisms and instability in the geology of the earth.
The simplest one is the “Caterpillar effect” which I have described so many times:
Earth in warming phase of crust – crust expands causing plates to push together so that one rides over the top of another. Crustal material is heated and then released (partly through volcanoes but also potentially as oil and gas)
Crust in cooling phase. The crust shrinks leading to contracting and separation at mid oceanic ridges. Here older mantle extrudes with relatively few gases being produced. The result is a reduction in volcanic emissions and the development of mid-oceanic ridges. There is good evidence this occurs from the modulation in activity of mid-oceanic crust formation in sync with ice-age cycle.
“Magma-weather”
And indeed, just as the climate shows weather patterns, and we now discern long term “weather” cycles in the oceanic activity, so we should also expect long term “weather” type variations in the ever moving magma within our planet, which undoubtedly is subject to the same basic laws as the atmosphere and oceans – of ever moving vortices of flux.
