Which type of internet is “greener”?

I was just thinking about this today?  With all the options for internet, whether dial-up (which some people do still use), DSL, cable, or satellite internet providers, is there one that is more eco-friendly than the rest?  Is laying cable for television and internet in the ground harmful?  Does the internet signal from broadband air cards wreak havoc with the atmosphere?  Does DSL create any weird radiation that we don’t know the side effects yet?  I’m not trying to scare anybody; this questions just popped into my head and I thought it would be interesting conversation.