I don't have a point to this reply, I'm just thinking aloud.

There's always a stream of CO2 being put back into the atmosphere from volcanoes. CO2 is also supposed to have a warming effect especially when it's at its lowest, so as it warms, CO2 is released and that has a warming effect. Warmists argue that the sun only pushes the train off the cliff, the CO2 keeps it running until the effect of CO2 balances with the rate new CO2 is emitted.

I imagine that retreating ice reveals a lot of methane in the form of decayed organic material and/or the CO2 from microbes munching on it. The first landscapes to emerge would be peat land which is a great absorber of CO2 and is supposed to absorm more per metre than rain forest. You'd think all those km2 of greedy peat bogs would stop the CO2 rising.

With the rising greening of the planet it seems that plant life automatically adjusts to how much CO2 there is. Plants grow smaller, slower, in less places and not so tall in poor conditions. During a glaciation large parts of the planet are desert, even when they're cold, partly because so much water is tied up in glaciers and there’s less rainfall, but maybe also because there's less CO2. In many ways the explosion of life after the cold stops and the CO2 increases is magical. It makes a mockery of life being unable to recover from manmade depletion. Sure, we may lose some interesting species but something else will make use of the vacant slot.

Many years ago I read something about the evolution of trees and their expansion to cover vast areas of the surface coincides with the start of major falls in CO2. I will have search for a reference

Interesting idea. However, Mars and Venus seem to have kept high CO2 ppm's despite very different planetary climate conditions. How does that relate to your speculation? However it is clear that plant life has increased, which means all life has improved, with the recent increase in CO2 here on Earth. Warming in oceans will increase CO2 in the atmosphere (demonstrating yet another fallacy in the climate crisis community). Coal and petroleum burning of course adds to that. And changes in land use, etc.
By the way, don't call your understanding simple- the climate kooks have that market cornered.

I do agree with RR and you as well, Dung: Earth has been blessed with triple point water, active tectonics, a relatively strong magnetosphere and most of all a great deal of life. They interact to recycle the carbon and other minerals over the long haul of geological time spans and to keep life viable.
If I recall correctly, Earth was a majority CO2 atmosphere until life figured out how to tap CO2 and release O2, trapping carbon. I like the idea that CO2 being repatriated into the atmosphere is a net good. It certainly has been for humans and the animals and plants we utilize.

Dung
Not exactly as I remember, but

The Decline of CO2 Levels and the Rise of Deep Roots
Archaeopteris was also the first plant to evolve deep roots. Roots eat away at rocks, burrowing into and dissolving them with acids in pursuit of nutrients. Over an immense period of time the weathered material gets washed into the oceans, where it combines with dissolved CO2 to form sediments that are eventually subducted into the Earth's interior by tectonic activity. This process removed huge amounts of CO2 from the oceans and atmosphere, with profound consequences for the climate. Between the beginning and end of the Devonian, levels of the gas plummeted by up to 95 per cent. Greenhouse conditions vanished, to be replaced by an ice age that at its peak 300 million years ago saw glaciers approaching the tropics.

Deep Roots and Large Leaves
But oddly it was the climatic upheaval brought about by roots that appears to have driven the next great innovation - large leaves. These first appeared 390 million years ago, but only became widespread with Archaeopteris 15 million years later. The stripping of CO2 from the Devonian atmosphere helped to remove an obstacle that had been inhibiting the evolution of large leaves.

From here Science and Evolution, notice that there's a nod towards CO2 and global warming.

Also this paper http://link.springer.com/chapter/10.1007%2F0-387-27048-5_1#page-1

Radical Rodent

Venus lacks water and plate tectonics. With no carbon cycle recycling volcanic CO2 back into the mantle the gas accumulates.

Entropic man
Isn't that another facet of RR's point? Nor does it address the Trees Question which includes a large element of indirect Carbon Capture and Storage in the paper is to be believed

SandyS

The classic example of RRs Trees Question is the Carboniferous period 300 million years ago. Extensive bogs and forests pulled CO2 down. This was the last time before the current ice age that Earth saw CO2 concentrations similar to Holocene conditions.

SandyS

Incidentally, the trapped CO2 became coal seams. That is the CO2 we are now returning to the atmosphere.

Entropic man
I think you need to read the paper and extracted I linked to.

Roots eat away at rocks, burrowing into and dissolving them with acids in pursuit of nutrients. Over an immense period of time the weathered material gets washed into the oceans, where it combines with dissolved CO2 to form sediments that are eventually subducted into the Earth's interior by tectonic activity.

A better hypothesis than AGW in my view.

Dung

On some things we agree, on some we differ. C'est la vie. ☺. We seem to agree on the mechanics of the carbon cycle and its long term effect on climate over geological timescales. We disagree on whether anthropogenic CO2 can affect climate over human timescales

SandyS

The long term carbon cycle and AGW are not mutually exclusive, though they operate over very different timescales. No reason why both be happening at the same time.

Dung
Although there appear to be several mechanisms for removing CO2 from the atmosphere, the only one not involving mass extinctions, especially of plant life, to return CO2 into the active environment appears to be by extracting the small amounts stored in "fossil fuels". The evidence suggest that this will be quickly recaptured and put back into storage.

Entropic man
That's an interesting combination,

The long term carbon cycle and AGW

Dung

If a major volcanic eruption hits coal seams or limestone you can get a lot of extra CO2. There was recent speculation that this may have contributed to the Permian extinction.