Did climate cool down when underground hydrocarbons stocks formed?

Question

As far as I understand, the dominant theory of modern climate change says that recent warming is mainly caused by the massive burning of hydrocarbons that used to be stored in solid form mostly underground as petroleum, coal, etc.

This suggests that the reverse process should contribute to a cooling of the climate (or to a slowed down warming if other processes are at play at the same time).

In particular, a cooling should have occurred throughout the period when the stocks of underground hydrocarbons were formed by the "pilling" of organic remains.

My questions:

1. Is this roughly what climate theory would predict or am I omitting some things?
2. Was such an effect observed during the formation of the underground stocks of hydrocarbons?
3. Can this reasoning be extended to say that a world where no solid hydrocarbons are burnt and the concentration of atmospheric hydrocarbons keeps falling (as it is captured by organism and transformed into solid hydrocarbons) would experience a continuous (if slow) cooling? Or are there some non-linearities by which the stock of solid hydrocarbons would "max out" or the effect of removing carbon from the atmosphere fade away?

Answer 1

Possibly

One thing you have to understand is that natural carbon sequestration via the formation of fossil fuel is VERY slow, it can take millions of years to build up the coal we burn in a day. In addition, one of the more dominant effects on the climate is solar radiance and continental position which changes over such long stretches of time, making matching such slow changes to carbon with climate change more difficult. Continent position also affects carbon sequestration and CO₂ concentration directly making it even more confusing. Things like seaways and deserts can have huge effects on CO₂.

The real problem is matching coal formation to changes in CO₂ concentration. Most coal comes from the carboniferous and the Permian time periods (along with the evolution of land plants that make it), the carboniferous saw severe cooling and severe drops in CO₂. How much of this is CO₂ lost to coal versus how much is just the formation of forests and other terrestrial ecosystems combined with changes in contingent positions is still up for debate.

The Permian however saw severe warming near its end and a rapid rise in CO₂ at the same time, but most of it was relatively stable and unchanging both in CO₂ and temp. It also included one of the largest volcanic events in earth's history, and again changing tectonic position. So although the link between CO₂ and temperature is really well established we can't even say for sure such slow coal formation actually reduces atmospheric CO₂ concentrations.

source

Compare CO2 above to temp (red line) below. Note that just three variables together predict temprature amazing well.

source

Answer 2

The carboniferous period was 350-270 million years ago. The content of CO₂ at that time was close to 3000 ppm, but this fell to 200-300 ppm by the end of this period. The average temperature of earth during this period was 20-25 $^{\circ}$C this fell to an average of 12 $^{\circ}$C by the end of the carboniferous period. So, the answer to your question is this, the carboniferous period ended because of climate change, the drop in CO₂ was the main reason for this.

A lot of CO₂ was also used in the creation of calcium carbonate (limestone) there was also heavy volcanic activity during this period this do lower the temperature at least in the short time during the eruption and a few years there after.

The last part of your question is basically can the CO₂ level get too low.

The level of CO₂ are regulated by plants if it falls, several things will happen,plants will grow slower the temperature on the earth will go down making plants grow even slower.

But this is highly unlikely to happen as long as the supply of CO₂ is continued.

edit:link http://www.geocraft.com/WVFossils/Carboniferous_climate.html

Answer 3

At the instant any atom of carbon is taken out of the atmosphere by a plant or animal and incorporated into its structure then that atom is "off the list" as it were with respect to having an effect in the atmosphere. Once in the animal/plant it may be there for eons until it becomes oil, coal,or whatever. So it is not the ultra slow conversion of organic matter to hydrocarbons that is relevant but the amount taken up by living matter on a daily basis which is sequestered into its structure.

Looking at the historical record we would therefore need to think about the amount of animal and plant activity on the planet and, to some extent, its type. This is quite difficult as we only have proxy records. however as we know that CO2 is effectively plant food it seems reasonable to assume that if the proxy record shows high levels of atmospheric CO2 we might expect that fairly quickly, a few year/decade timescale, that plant life on earth would respond quickly and become very lush indeed.

This is of course only one factor with respect to CO2. Past volcanic activity is likely to also be relevant.