Carbon dioxide is the gas which makes soda pop fizzy and forms the bubbles and the “head” on beer. It is also the gas that makes that pizza dough light and bubbly. It occurs naturally in the earth’s interior as a result of igneous rock differentiation processes. During volcanic eruptions it is vented into the atmosphere from the earth’s interior, along with water vapor and other gases. In our modern atmosphere CO2 gas amounts to only a tiny fraction of the air we breathe(less than 0.04% by volume of dry air), but that small amount is exceptionally important. Beside arising from the earth’s interior, carbon dioxide is also formed on the earth’s surface as a waste product of oxidation and animal metabolism. Carbon dioxide is an essential element to the process of photosynthesis, by which carbohydrates are produced by combing CO2 and H2O in the presence of chlorophyll. Photosynthesis releases the oxygen necessary for life, as a gaseous waste. Carbon dioxide gas in the atmosphere also functions to soak up heat in the lower levels of the atmosphere, absorbing earth long-wave radiation and holding that heat like a gaseous blanket which helps to warm the lower atmosphere. For that reason, it is classed as one of the “greenhouse” gases, keeping the earth warmer than it would normally be based on how much solar radiation it receives.
Over most of the last nearly one-million years the concentration of CO2 has remained remarkably steady in the atmosphere and up until recent times so has the earth’s temperature. This “steady state” of CO2 is the result of the cycling of carbon from the atmosphere into the biosphere (plants) and back again into the atmosphere in about equal amounts. In the “carbon cycle” photosynthetic (mostly green) plants remove CO2 from the atmosphere and fix it as a simple carbohydrate, from which plants generate sugars, starches and insoluble cellulose, and in the end release oxygen as a waste. Plants also consume the oxygen they produce for their own metabolism. While animals (which use the oxygen for their metabolism) complete the cycle by consuming the plant-formed carbohydrates, combining them with oxygen and releasing CO2 as a waste of metabolism back into the air. Thus when Mother Nature held unrestricted sway over the earth, the tiny percentage of CO2 in the atmosphere remained stable and minuscule at about 4/100s of one percent and the earth’s mean surface temperature kept steady too at about 13 degrees C or about 55 deg F.
But enter the human species. According to Ancient Greek myth, it was Prometheus who created man out of clay and then tricked the Gods out of the meat from sacrificial offerings (the Gods got only the long bones and some fat or skin). Zeus, displeased with this effrontery, hid fire from the earthlings, but Prometheus stole a burning brand from heaven to comfort his human creation. However man acquired fire, once they learned to make fire and use it, they developed a penchant for burning things up. Wood was the main fuel of early man. By using wood as a fuel, man simply converted the cellulose and lignin created from atmospheric carbon and water, back into those same substances. As a result, no additional carbon was added to the earth’s atmosphere. But man is very curious and inventive, something Prometheus may not have planned on or foresaw. Upon the discovery that other substances, other than wood (which is difficult to cut, dry and haul) would burn and produce heat, man quickly began to exploit these substances. coal was the first and easiest to exploit.
Very early in human history man learned that some “rocks” would actually burn even hotter than wood. They quickly began to exploit the outcrops of coal or seams at the surface, even dig down into the earth to extract this, light-weight, black material. As far back as 1000BC the Chinese used coal, the “rocks that burn", extracting the light weight rocks from the Fushun Mine in northeastern China to smelt copper. As a result of, the Venetian, Marco Polo’s travels in late 13th century AD in China, (@1271-1291) Polo was able to report in his travelogue the remarkable observation that the Chinese used “black stones” which “burned like logs” to heat water for their baths. He added the astounding fact (for cold, unwashed, Medieval Europeans) that the “stones” were so plentiful and widely used that the common people could take “three hot baths a week!”.
The Romans also exploited coal for smelting and to heat water in the hypocausts under their communal baths. Soon after the Roman invasion and colonization of Britain, initiated under Emperor Claudius in 43AD and lasting to about 409AD, the Romans mined coal to smelt British tin and copper, to burn limestone to make quicklime for concrete, and as a source of fuel to heat water in public baths.
From those early beginnings the use of coal and other fossil fuels, such as oil and gas, expanded exponentially to eventually provide the major sources of energy for the Industrial Revolution. In 2011,according to “coal statistics", world coal production reached 8 billion tons annually and its use was still growing by about 7% each year. Coal is approximately 70% carbon, so when it is burned its carbon is converted into CO2 and that waste gas is simply voided into the world atmosphere to add to the total burden of that gas in the atmosphere. In 2010, the world economy consumed nearly 32 billion barrels of crude oil, while in 2010 natural gas consumption reached 113 trillion cubic feet or 3 trillion cubic meters (doubling in use since 1980). These fossil fuel resources are burned when they are used and the carbon dioxide waste is dumped into the atmosphere. Some have estimated that human activity adds about 29 gigatons or 29 billion tons (tonnes?) of carbon to the atmosphere annually. But this (0.04 %) amount is small compared to the approximately 750 gigatons cycling in the earth oceans and atmosphere at any one time. However, it is "new" carbon and it is added to the already existing carbon, over the over two hundred years of industrial activity that amount has accumulated. It can not be absorbed without consequence into the earth or atmosphere and slowly builds up to alter the climate.
The vast majority of fossil fuels were formed from plants and other organic materials hundreds of millions of years ago. The deep burial of these concentrations of carbon in sedimentary structures sequestered the carbon from the atmosphere and removed them from the carbon cycle. During the industrial revolution beginning @ 1750 these fossil carbon sources were mined, and consumed (i.e. burned, or combined with atmospheric oxygen), which resulted in the release of the ancient carbon dioxide back into the atmosphere. It is this “ancient” carbon which is spewed out from every internal combustion engine,every home heating plant that burns fossil fuel, every coal and oil fired electric generation plant, every car, every truck, every motorcycle and lawn mower which dumps newly formed carbon dioxide back into the air and adds to the formerly stable carbon burden of the atmosphere.
Today (as of October 2012) the concentration of carbon dioxide or CO2 in the Earth’s atmosphere is 391 ppm (parts per million) That is significantly higher than the value of 280 ppm calculated for the pre-industrial era. Thus the present high level is about 1.4 times greater than the pre industrial period in human history. That is an uncontested actual fact. Annual measurements of CO2, (which are generally made in the well-mixed, far from industrial contamination, pristine air on the slopes of Mona Loa on the Island of Hawaii) indicate that the value has been increasing steadily since the first measurements in the last century and between 2000 and 2009 in this century at the rate of about 2 ppm/year. That is also a simple scientific fact. No, there is no opportunity to formulate your own opinion on this.
Though the overall graph-trend of CO2 concentration in the atmosphere is still rising, the recent economic downturn or Great Recession of 2007-08 is reflected in a corresponding slight decreases in that rate. It is noteworthy that the CO2 curve closely follows a graph of the world economy. In an expanding economy, when we all use more fossil fuels, the CO2 levels rise too, and when we use less energy they fall. Thus the correlation between human economic behavior and the CO2 concentration is very close. This fact alone strongly supports the general scientific opinion that the fluctuations are anthropogenic. If we accept the fact that our industries and behavior can control carbon levels then perhaps we can do something (or stop doing some things) to modulate the increasing concentration and the even now observable climatic consequences.
Get the picture?
rjk
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