I thought I'd learned my lesson before... to stay out of these type threads...
(All that about 'being beaten with experience' and that)
But, heck... I guess not...
[RANT ON]
Since about 1750 human activity has increased the concentration of carbon dioxide and other greenhouse gases. Measured atmospheric concentrations of carbon dioxide are currently 100 ppmv higher than pre-industrial levels.[1] Natural sources of carbon dioxide are more than 20 times greater than sources due to human activity,[2] but over periods longer than a few years natural sources are closely balanced by natural sinks, mainly photosynthesis of carbon compounds by plants and marine plankton.
  1. "Climate Change 2001: Working Group I: The Scientific Basis: figure 6-6". http://www.grida.no/climate/ipcc_tar/wg1/fig6-6.htm. Retrieved 1 May 2006.
  2. "The present carbon cycle - Climate Change". Grida.no. http://www.grida.no/climate/vital/13.htm. Retrieved 2010-10-16.
That is from THE GLOBAL WARMING ALARMISTS THEMSELVES.

Use the brain God gave you...

If natural sources of CO² are 20 TIMES higher than sources due to human activity - and the natural fluxations (sinks and rises) are therefore 20 times higher...

And CO² is not the largest... but the SECOND largest greenhouse gas:

Water Vapor - H2O 36 – 72%
Carbon Dioxide - CO2 - 9 – 26%
Methane - CH4 4 – 9 %
Ozone - O3 3 – 7 %
What should we do?
Oh - yeah...

The GOVERNMENT should spend freaking BILLIONS of the USA's (your) money to forcibly modify human behavior?

The GOVERNMENT should install thermostats in YOUR HOUSE so YOU don't use too much energy?

For a half a degree of temp over a hundred years?

Haven't you seen the proof that plants grow better in a richer CO² environment?
That, my friends is what you call a mutualistic, symbiotic relationship...
Just one of natures little checks and balances that we are just TOO FREAKING SMART TO UNDERSTAND.

One thing these folks never mention is the supporting data that reveals the industrial revolution is directly responsible for them being alive.
Yes - IT IS the reason the expected human life span has increased from ~30 to ~65...
Doubling your expected life span...
gotta stop that...
and while your at it...
Do us all a favor and stop breathing.

Sheeh - normally sane people, hypnotized with this 'climate change' spiel turn their brain directly to the OFF position.

To summarize MY PERSONAL POSITION on this matter:
Yes, humans affect the atmosphere.
Albiet, not in the grandiose way the alarmists would have you think.
Is that necessarily a bad thing? What YOU PERSONALLY DON"T KNOW?!
All the possible negative implications are being blown out of porportion...
For what you ask?
MONEY, YOU FOOLS.
[/RANT OFF]
Ahh...
Breathe in... the fresh air.
Breathe out... the destroyer of worlds.