what is the average distance of greenhouse gases from the surface of the earth?

Answer 1

Well the CO2 is on the ground where the plants are to recycle our air and the plants are doing a great job.
Methane is a very light gas so I would look for it about 50 miles up . Except the intense sun oxidizes it and it falls to earth as CO2.

Answer 2

There is no good answer, because:

The atmosphere has a complex structure. It is basically layers. Within each layer everything is pretty well mixed, but there is limited mixing between layers.

The lowest layer is the troposphere. It goes about 35.000 feet up and contains 80% of the entire atmosphere.

Since global warming gases are created on Earth, they're mostly in the troposphere. It gets thinner as you go higher. So something like 10,000 feet???????

Note that I'm talking about total amount. The percentage amount doesn't vary a whole lot in the troposphere, which is pretty well mixed.