Has the amount of CO2 in the atmosphere gone up by 0.01% or something thousands of times greater?

I keep hearing one "skeptic" talk about CO2 only going up by 0.01%, so I'd like to know how much the AMOUNT of CO2 has gone up (kilograms, pounds, tonnes, whatever). Isn't it the amount that matters to the greenhouse effect? Since nitrogen, oxygen, argon, etc., are not greenhouse gases anyway, I'm not sure why anyone would want to only characterize the change in CO2 with reference to those gases (unless they were trying to mislead people, of course).