Scientists don't just study their whole lives to not learn anything first of all. Spoon fed and scientifically sound are two totally different things.
First some perspective. Here is a massive photo of Venus, just to give you the idea of what we are talking about here.
Here's a smaller one if that one hurt your eyes.
We know the Venusian atmosphere contains high concentrations of CO2 and droplets of Sulfuric acid. We know this, it isn't that hard to figure out the composition of a planet's atmosphere.
A spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials.
Why is the CO2 there? That's easy! Its a heavy gas. Volcanoes release massive quantities. No volcanoes on Venus? Ummm, we can see them! Where gravity is applied CO2 will sink, the more of it we have in the atmosphere, the more weight it will put on the surface. Matter is attracted to matter, especially a big ball of it (It's known as gravity.). Venus has an extremely dense atmosphere. There is a lot of CO2 in it.
Watch the Experiment at :30
As a heavy gas CO2 stays closer to the surface, but if you get enough on it it will start to gain density. The higher density per volume and you create a super high pressure gaseous atmosphere.
Greenhouse gases are gases in an atmosphere that absorb and emit radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect.
Believe it or not water vapor, not carbon dioxide, is the primary greenhouse gas on earth. CO2 is not extremely heavily concentrated. On Venus it is not only heavily concentrated, but freaking heavy!
CO2 is a perfect example of a greenhouse gas. It is a heavy absorber of heat.
Lets watch a video about the Venus CO2 buildup.
[edit on 4-11-2009 by DaMod]
Also, if this is total nonsense then please explain to me why? 
