Do you know what percentage of atmospheric gases is CO2?

0.035%

http://en.wikipedia.org/wiki/Earth's_atmosphere (Pie chart a little bit down the page.)

Let's say, just for argument, that the amount of CO2 in the atmosphere doubles. Then it makes up 0.07% of the earth's atmospheric gases.

This is not going to kill us.

"Carbon emissions for U.S. territories range from 9 to 12 million metric tons per year." http://www.eia.doe.gov/oiaf/1605/gg99rpt/appendixa .html

One metric ton is 1000 kg.

"Volcanic activity now releases about 130 to 230 teragrams (145 million to 255 million short tons) of carbon dioxide each year." http://en.wikipedia.org/wiki/Volcano

One short ton is 2000 kg.

Let us compare. US activity gives off 18-24 million short tons, volcanic activity 145-255 million short tons, of CO2 each year.

How much can we affect climate change if our entire CO2 emission is 1 percent of that of a single natural source of CO2?