Do Catalytic converters help or hurt Global warming?

Given the correlation between the widespread use of catalytic converters in cars since 1970 and the increase in the earths temperature, is there a possibility that we have created the problem with catalytic converters? When they were mandated in automobiles the issue was not global warming. It was smog. The smog is the result of the biproducts of combustion that creates nitrous oxide (N2O) and lays low in the atmosphere and makes our air unhealthy to breath. CO2 is the biproduct of catalytic converters and CO2 is the single largest element causing global warming. Is this a major source the global warming problem? Shouldn't we be doing something to change this trend?