Scientist claims CO2 % in atmosphere not rising

This is a common piece of misinformation currently doing the rounds of the internet via email and climate-change-deniar blogs, the notion that there is a natural force keeping CO2 in check.  However, this theory is fundamentally flawed, as follows>

The theory suggests that because the amount of carbon dioxide human activity generates that remains in the air is around 43%, then nature is preventing CO2 from rising to dangerous (warming) levels.  Now, forgetting for a minute all the statistical confirmation of warming trends presented earlier, how can we explain CO2 remaining in the atmoshere at a level of 43 %.

First, you have to ask, percentage of what ?  The common misperception (intentional of couse) when someone reads this is that CO2 remains 43% of the total gases in the atmosphere.   This is not correct, we are not referring to 43% of the atmosphere, we are referring to 43% of emitted CO2. 

So if we are currently emitting 29 bilion tonnes of CO2 a year (current estimated levels), of that 29 billion, 12.6 billion are added to the atmosphere.  Now if we look back 100 years, lets estimate a CO2 production of 2 billion tonnes, equivalent to 0.4 billion tonnes of CO2 entering the atmosphere.

Using this trend, we can see that the amount of CO2 our activity is putting into the atmosphere has gone up significantly.   Simple mis-representation of percentages and data is a common tool used by interests trying to stall climate change legislation (think of all the false stories the tobacco industry paid for to cast doubt about the link between smoking and lung cancer over three decades).

[ further reading : http://www.skepticalscience.com/co2-levels-airborne-fraction-increasing.htm ]