To make it more clear, 360 PPM (parts per million) means that "for each molecule of CO₂ there are 27 molecules of something else" in Earth's atmosphere.

Assume that we (people) are resposible for half the CO₂ (not really proven), then about 55 out of 56 molecules in Earth's atmosphere are not our responsibility.

If we cut CO₂ emissions by 10%, that would reduce anthropogenic CO₂ by "one molecule out of every 550". Of no concequence at all, except for the cost.