The fossil record shows both Methane and CO2 in the sequences of glaciation studied By the Snowball Earth Hypothesis. The Prime actor between these two gases…Oxygen, is very important, as it is used up by Methane as Methane is broken down into CO2 and water. Here is another natural action that may not have been fully captured by the hypothesis- Once the plant matter is rotting after a cooling event which causes plant die off, the decomposition process gives off Methane which will eventually become CO2.
So we witness discussion like this, where the headline is confusing the ordinary reader.
At this point it should not be a discussion about Carbon Dioxide only- as Methane is so often the precursor gas which sponges up the cooling oxygen gas (hydroxyl) which triggers or encourages cooling of the Earth.
But this article points out that CO2 is not the warming trigger according to their assessment and also that levels were potentially very high in the fossil record- over 1000 ppm. This suggests that methane was very high-essentially up to the same ppm level to cause that CO2 level. This would cause warming by removing 6 O atoms per CH4.
The thermostat is a relatively simple relationship between Oxygen and Methane, and now anthropogenic CO2, with a longer term, blanketing protection from water and CO2 as Methane is broken down. The water vapor warms at lower altitude.
Presently we are injecting combustion CO2 without a Methane precursor and other greenhouse gases which also have depleted the oxygen for the ozone layer. The real impact has been the cooling action from the plant exhalation of oxygen ( that is ionized in the high atmosphere) which is well recorded. It then rots and gives Methane/CO2 which effectively rewarms.
Therefore if plants can affect this thermostat, we should look there to the oxygen and how it changed the available Methane, then that resulting decomposition to CO2 and water which then fed another cycle of plant growths, and went around again in this simple cycle. These gases were always present once plant life was here. It is the ratios which we want to check against that record in order to find the applicability.
The more powerful than CO2 gases are subject to oxidation and promote cooling ( heat venting) by their absence mathematically and physically. Their control requires oxygen, either natural or provided via direct remediation. Our problem is having all of these releasing all at once, including Methane from permafrost.
The warming caused by all of the co pollutants from combustion cause warming and are called short lived climate pollutants. However in September 2010, a Methane blowout process now occurring will be far more serious. The antidote to the Methane is one gas- Oxygen-best delivered in the form of an ion called the hydroxyl. In the fossil record, there are cases where oxygen and its oxidation of methane has caused a snowball Earth, when CO2 levels were low enough to allow heat venting. Presently we can count on only about 2’C of this cooling, but even that may be a pivotal and necessary opportunity we must take. We must seriously consider some forms of carbon rationing, either at national levels, or target high emitters, to make any cooling successful.