The Ice Core graph shows a very unusual increase in CO2 levels over the last 100 years, and this is almost certainly associated with human activity (and this is what most "Global Warming" people are worried about).
However, above and beyond that, the graph also shows a very distinct pattern which has nothing whatsoever to do with human activity. We are living in a natural warm spike which has been developing over the last 10,000 years. And every single warm spike before this one has been followed by a dramatic and protracted decrease in global temperatures.
It seems unlikely that any amount of CO2 is going to cancel out whatever natural force (probably thermohaline) which triggers a natural temperature crash. If anything, adding CO2 to the atmosphere is probably going to push us over the "ice age" precipice even faster.
The global forces which drive the pattern below will assert themselves regardless of how much CO2 we add to the atmosphere.