Logicalscience: Cars

"Cars Amount to Only 6% of Man-Made CO2"
Part of the: Common Arguments by Skeptics and Deniers series

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This argument has been made on digg, among a few other places. Nobody ever provides a source but I see this stat pop up somewhat often. If you find out who the initial source of this little factoid is please post in the comments section. Now it's time for us to R.T.F.R. Straight from the Department of Energy's report:

Although transportation is a vital part of the economy and is essential for everyday activities, it is also a significant source of greenhouse gas (GHG) emissions. In 2003, the transportation sector accounted for about 27 percent of total U.S. GHG emissions, up from 24.8 percent in 1990.

And now for a little fun with math. Lets see how big his/her goof was.

27 (DOE stat) / 6 (Denialist/Skeptic stat) * 100 = 450%

Which basically means this denialist/skeptic has error bars 450% larger then his facts. And to be honest his/her error bars are even larger than that because:

Estimates of GHG emissions do not include additional "lifecycle" emissions related to transportation, such as the extraction and refining of fuel and the manufacture of vehicles, which are also a significant source of domestic and international GHG emissions.

The simple act of driving around in America released a total of 1,958.6 million metric tons of CO2 in 2005. And transportation energy use is expected to increase 48 percent between 2003 and 2025. All of these statistics are for America. There are 6 billion rapidly developing people on the planet. It is quite a stretch to even imply that fossil fuel powered cars are not a threat to the environment. Again, if you know where this myth originated please post a link.

Update for clarification:
In 2003 the US emitted 1,848.8 Tg of CO2. Only 4.3 Tg of that is from electrical sources. Since almost all of our transportation (about 99.76%) comes is powered by oil I thought it was prudent to lump all oil powered forms of transportation together. If you want to limit the discussion to passenger vehicles I would suggest we change our number from 27% of total emissions to 17% of our total emissions. It's still a sizable sum. Still, if we can remove oil from privately owned light trucks (Ford F150's, Dodge Rams, etc) and passenger vehicles then we should be able to do the same with heavy duty vehicles. At that point 'cars' are responsible for 22.14% of our yearly CO2 emissions. The only question remaining is whether or not we can power our aircraft with some form of biofuel.