Today's part - the decay of organic matter into what we would consider crude oil (fossil fuels).
Argument So Far
Plants pull CO2 out of the atmosphere to build plant matter (yes, that whole post boils down to this).
When plant life decays, it merely reverses the process of how they formed :
C6H12O6 + 6 O2 → Decay → 6 CO2 + 6 H2O
If plant matter manages to die and lay in such a way that access to oxygen is limited, it can be preserved from decay, locking away the stored carbon. This can occur in places like bogs, that are stagnant water, or buried under sediment under lakes and oceans. 
The biomass that's locked away can be turned into crude oil by a process called thermochemical conversion (TCC), where under intense pressure and heat long-chain biomass molecules are broken down into short chain molecules like hydrocarbons - such as oil. 
Coal, which is essentially a burnable rock, and forms in a somewhat similar fashion to oil. Peat needs to die, be buried in sediment, and heated/compressed such that the water is squeezed out. This process is called "coalification." It's estimated that it takes about 10 feet-thick worth of peat to compress into 1 foot-thick layer of coal. 
Plants have existed on this planet for at least 475 million years . In that time, oil and coal have formed as plant life dies and undergoes the process for building up fossil fuels.
How this ties into the argument
First, I established that plants pull CO2 out of the atmosphere and are in a loose sense solidified CO2 (in a very loose sense).
Then, they die and are buried in the ground, either on land or sea, and through chemical/geologic means, are converted into oil/coal. This locks the potential CO2 out of the atmosphere for a very long time. This process builds up hydrocarbons from CO2 that no longer circulate in the air.
I probably should research what quantity is pulled out, but I think if we measure how much we're extracting now, that would basically be equivalent. There's no point in looking up both figures.
Part of my point with this aspect of the argument is that we're pumping a huge amount of carbon dioxide into the atmosphere. If it takes 200 years to use it up (1900 to 2100), and it took about 500 million years to build it up, that would be like using your entire life savings, over the course of 80 working years of your life, in a whopping 17 minutes.
That's how fast we might be using it. Even it it takes us 400 years instead of 200, that means we'd be blowing our life savings in 34 minutes instead of 17.