We've decided as a species to do nothing about our emissions and let what happens happen. So who cares what does or doesn't make a difference?
We have an ambitious goal of getting down to 1 trillion (or even 250 million) tonnes of CO2e per year by 2050 because of how bad things will get if we don't.
As game theory (and the tragedy of the commons) would suggest, there will be cheaters. But those cheaters are not overwhelming the overall downward trend.