The sentient AGW point is that the burning of fossil fuels is recreating what existed before the carbon dioxide that they were created from, was sequestered in them, in the ground.
We know what happened the previous time that all of that carbon dioxide was in the atmosphere rather than locked up underground.
Why would anyone expect this time to be any different?
What ?
Wait....
You're telling me that we are going to revert geologically and atmospherically/climatologically, back to a previous state, because CO2 wasn't in the ground but in the air and so it will return??
Well as colorful as that is, it would show a cycle wouldn't it. And so far no one on the AGW side is willing to concede that there is a pattern so I don't think that's the case here..
Also, Co2 isn't just from the breakdown of bio-matter as we know it. it also comes from the earth itself volcanoes produce a great deal of it. No dead bio-matter needed, lots of things can produce it naturally with or without carbon-based life forms.
Here's what is indisputable. Carbon dioxide is a greenhouse gas. That means it's transmissivity is higher for the spectrum of radiant energy from the sun, than it is for the spectrum reflected back from earth. Energy is trapped on earth.
Fossil fuels are made from biological waste trapped under ground which is made from carbon dioxide.
We know during the years that fossil fuels were sequestered from the atmosphere that atmospheric CO2 concentrations predictably went down, and so did global average temperature. (The Carboniferous Period occurred from about 360 to 286 million years ago). Look at the graph that you referenced for that Period. Look at what happened to CO2 concentrations and global temps.
Cause and effect predictable from energy balance. Animal life could not flourish at the start of that period. It did after that period.
For the last 100 years we've been steadily returning to the CO2 concentrations of that period by releasing all of that sequestered greenhouse gas.
Now, we could do nothing and hope that something that we don't know about will save us from what we do know about. But, we know that we will run out of fossil fuels anyway.
So, despite what you wish, private industry is investing in sustainable energy, and the transportation industry is working hard on getting more good, and less waste out of each pound of greenhouse gas we dump into the atmosphere.
We already spend billions of dollars and thousands of lives every year recovering from AGW enhanced extreme weather.
It's pretty certain that the lowest cost path, based on what we know, goes through fixing, rather than ignoring, AGW.