Possibly true. I'm not sure of your numbers. But utterly irrelevant.
For all practical purposes the other 97% circulates in the ecosphere, being removed from the atmosphere by plant growth and released back into the air when the plants (and the animals who feed on the plants and each other) decay or burn.
The net increase in CO2 we have been seeing for about the last 100 years is just about 100% anthropogenic, a result of burning fossil fuels that had sequestered massive amounts of carbon for millions of years.
Whether and how destructive that is can and should be debated. But that we are significantly increasing CO2 is just a fact. As is the fact that this has never occurred before and nobody on either side of the debate should be too positive on what its effects might be.
Note my tagline.
According to them, CO2 levels have been increasing for over 500 years, which predates the industrial age and it's burning of sequestered CO2.
What "climate change/global warming" zealots claim is that Man has the power to change the weather, and on that, I call B*LL$H*T! Man has yet to understand the weather, much less change it....