http://www.skepticalscience.com/peter-sinclair-interview-with-michael-mann.html

I'm having a little trouble encoding the video, though.  I have to try one more thing to see if I can make it work...

Ah... I got it.

You say that Wegman is not a climate scientist, that's not the point.

You do not need to be one to know that we do not breath CO2 because the air mixes continuously, you don't even need to be a scientist.

You don't need to be a scientist to understand that you don't suffocate when you go into low lying valleys.