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  Question 4 Answer B
carbon dioxide (CO<sub>2</sub>)
The so-called 'Greenhouse Effect' is caused primarily by:   b) carbon dioxide (CO2)

No, that is incorrect.

It has not been proven that human additions to atmospheric CO2 (primarily through the burning of fossil fuels, land use change, and plant decay) are causing the Earth to warm significantly. CO2 levels and temperatures varied widely, rising and falling, long time before human civilization.

Carbon dioxide is actually a tiny constituent of our atmosphere-- comprising less than 4/100 of 1% of all gases present (385 part per million by volume). CO2 has been generally increasing for the last 18,000 years, coinciding with an interuption in the Ice Age and the subsequent onset of warming. Although there appears to be a relationship between increases in CO2 levels and global temperature, it has not been proven that the relatively small amounts of CO2 added by humans has raised or will raise global temperatures. More importantly, temperature changes are seen to precede CO2 changes, in complete contradiction to the fundamental assumption of the human-caused warming hypothesis. Rising global temperatures due to increased solar input may simply allow Earth's oceans to surrender more CO2 to the atmosphere, similar to a warm bottle of soda pop which burps and fizzes when opened because cold liquid can hold more CO2 than warm liquid.


At first glance, the graphs at left appears to indicate that rises in CO2 drive increasing temperature. However, a closer look at the data (below) shows that CO2 rise lags temperature rise by about 800 years.

Caillon et al. (2003, Science, 299, 1728) make the point, “This confirms that CO2 is not the forcing that initially drives the climatic system during a deglaciation [warming out of ice ages]. Rather, deglaciation is probably initiated by some insolation [solar] forcing.” In fact, temperature changes precede CO2 changes in records of any time period in contradiction to the basic assumption of the theory that human CO2 is causing temperature increase.

Did you know. . .

192 – 224 billion tonnes of carbon (Gt C) in the form of CO2 are emitted into the atmosphere each year. Of this total over 95% is from natural sources. Here is the breakdown:

Respiration Humans, Animals, Phytoplankton              43.5 - 52 Gt C/ year

Ocean Outgassing (Tropical Areas)                                 90 - 100 Gt C/year

Volcanoes, Soil degassing                                                 0.5 - 2 Gt C/ year

Soil Bacteria, Decomposition                                            50 - 60 Gt C/ year

Forest cutting, Forest fires                                                0.6 - 2.6 Gt C/year

Anthropogenic [human-caused] emissions (2005)      7.5 Gt C/year (UN estimate)

TOTAL:    192 to 224 Gt C/ year

Notice that the human contributions (anthropogenic emissions) are less than the range of the estimate in three of the natural contributions.

The Global Carbon Cycle: The numbers represent the sizes of the reservoirs of carbon and the amounts moving between these reservoirs in Gt C.

Most CO2 is eventually locked up in ocean sediments as phytoplankton die and the carbon in their bodies falls to the ocean floor.

CO2 from all coal burning worldwide comprises only 0.013% of the greenhouse gases in Earth's atmosphere.


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Produced with the assistance of Dr. Tim Ball & Tom Harris, B. Eng., M. Eng. (Mech.), Executive Director, International Climate Science Coalition.
CSCCC FCPP is a member of Civil Society Coalition on Climate Change.
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© Frontier Centre for Public Policy 2017.