Feel Better:Complain About Anything, page-86817

Couple of analogies I use
You have a gold fish in a tank and you put a drop of bleach in it every now and again, that drop of bleach will disperse, evaporate and gold fish will be fine. But if you add more drops of bleach and more often it doesn't disperse and evaporate as quickly, the concentration of bleach in the water increases to the point it is too polluted for the fish to survive.

We found out about that the hard way when we use to dump toxic waste in rivers and land fill, we had to stop doing that, industry didn't like having to stop that because it was going to cost a lot more to dispose of toxic waste.

Next one
You have an enclosed garage, you can run the car engine a bit and the amount of carbon monoxide is not enough to hurt you. How ever if you run the car engine long enough the levels carbon monoxide will get to the point it will kill you.

The earth is an enclosed atmosphere, at some point it can not absorb the pollution that is emitted and the concentration of pollution has to have adverse effects on the envioment

One more point, CC deniers will say that CO2 is not harmful and it is actually good because plants use it. The ignore that if we are pumping out more CO2 that plants can absorb we end up with an imbalance of excess CO2 in the atmosphere. It's like H20 is essential to like but if you have to much of it, it cause problems