Your questions are what we would like to answer as well. However, I and others are not going to jump up and say the sky is falling simply because a leaf falls from a tree and partially shades the site of the sky from our eyes. Also, I request that you do not get me wrong, I am an avid environmentalist and strong alternative energy advocate. However, I desire strict integrity in thought and presentation of data. I too may fail to maintain the desired integrity, that is why as we jointly search for answers, the diversity of opinions and observations that can be found here are so important. (PS: Snow, thanks; but, I only attempt to maintain the integrity based on the stated intent for this forum. (Note: Succinct is not a common word usually paired with my musings.) )
Granted there is a lot of contribution by the human animal; however, it has not significantly changed in the last 100 years averaged over the population count. (Yes I know this flies in the face of an earlier position I shared and I will explain it further.) In essence, humans have always had the need for a carbon based energy source. Whether it was for heat or meat up until about 1000 (AD). It was during this time frame the beast of burden was changing from the backs of man to the backs of the beasts. The luxury of owning a animal simply for the purpose of transport or bearing burden was an outgrowth of the use of such beasts for the purpose of war. (When the war ended what did you do with the animals...)
Hence, there were increases in the population of the beasts of burden that exceeded the normal populations. It is this difference due to the husbandry of humans that begins to add to the carbon increase to the atmosphere. When you add in the increase in human population an the increase in beast of burden population to meet the needs of the humans you begin to increase the amount of conversion of the surface bearing carbon to atmospheric due to two things one the removal of the carbon from the natural soil sequestration and two you interject an increase in the rate of the release of carbon oxides into the atmosphere. That the increase in mankind's populations began to exceed the surface capacity to provide for the carbon needs of man he began to locate alternatives to meet these needs. Hence, the turn to sequestered fuels such as peat and mulch. When this proves in effective, we then find the resources that had been laid aside many millions of years ago and we begin to return to the a small portion of the original CO2 it contained, (coal). We got to the point we no longer needed as much of the surface carbon; hence it could return to the soil if necessary. But, alas, the populations of man decided to undertake to produce foods in excess of what they actually needed and partially used this to increase the capabilities of their beast of burden and partially in trade with those who did not have the capacity to raise foods for themselves. (The merchants would have starved had there not been the opportunity for trade.)
This demand to provide foods in excess of substance driven by the increasing human population began to encroach on the increased soil carbon content and was accompanied by the reduction of trees to meet the demand for foods stuffs. In short, with the growth of capitalism also began the artificial changes in natures respiration of CO2. When the refuse from the beasts of burden became an issue and the technology started to develop due to the industrial revolution ("ir"), (Keeping in mind that the start of the "ir" was the production of cloth driven by water wheels and not steam engines.) It was not until the
turn of the 20th century that factories became more dependent on coal reserves rather then wood reserves or running water locations. Part of this was due to the change in the US to begin to follow mother Britain in the production of steel for it's ships of war and eventually its tall buildings. With the increase demand for coal for heating for the increasing populations, with the demand for the energy to convert iron oxide ore to iron and then to carbon steel, with the demand to change from a transportation system that the waste product did not pile up into vast mountains on the perimeter of the towns and cities
However, by this time vast natural expanses of regions that would sequester atmospheric carbon were disappearing and the global CO2 respiration signature began to modify. It is unlikely that the increase in the atmospheric carbon can be directly related to the addition to the fossil fuel generation of 100 years as much as it was the change in the natural sequestration of the carbon cycle that has had the impact we see today. A mere 40 years of 5-7.5Gt of carbon by human fossil fuel burning is a drop in the bucket compared to the losses in the natural carbon cycle over the last 1000 years.
So you ask the obvious question, if the problem is not due to humans adding to the problem then what is driving the CO2. That is where the new research is so important. Dr. Mason and I had a brief discussion about two months ago in regards to the Chalk deposits and his comment was that the calcium content of the oceans was very high. However, the value was static. If indeed there was an increase in the CO2 I would have expected the calcium would have countered the increase, until I discovered that the majority of the calcium was locked up in a carbon compound already. So this then drove a little more research. It appears there are vast turnovers of calcium, carbon and oxygen at tectonic boundaries. The thought had been could this be a major source. When I look at the data of the geologic generation of gases they are even less then those added by humans. So the issue is not that there is more CO2 being added; but, less being removed in my opinion. However, the amount that is present is the result of the necessary amount to maintain the human animal.
The basic argument is whether or not the rapid increase in CO2 is due to increased demand of fossil fuel carbon or due to other processes. So far we are only accurate in the ascertaining of the carbon flow of humans. We need additional detailed data as to the carbon respiration of nature before we get out our sack cloths and ashes... In the meantime, we should be doing everything reasonable to reduce our carbon footprint where we can. And where we can't, try to make it a conscious decision of whether or not this is a necessary polluting activity.