Pollution and Airline Code share

Pollution and Airline Code share
As we know, the airplanes make a big air pollutions, there are so many flights in the air and pollute the air. But there is a strange situation, the seats in plane is hard to be taken fully in every flights, and some airlines have the same lines, so there are many planes in the air, and there are not fully being taken by passengers. So the code share can reduce the air pollution, and decrease the cost of each airline, and they can get more benefit and do not need more pollution permits.
For example, I took the flight CA982 from New York to Beijing, at the same time the flight is UA4451, even this the plane was not full, imagine if there are planes to fly this line, there will be more most of Air China and United, and there will be more air pollution.