Singer's apparently was. Michaels has been saying similar things for about five years. Hard to tell on Christy. I remember a magazine profile on him from several years ago (pre-2000?) where I seem to remember him saying things similar to my characterization.
Sorry, it was 2001. And his "conversion" was more recent than that.
Then there's this: Christy on global warming
Looking for Christy, I found this (in case you don't think I'm a good source):
The Great Global Warming Swindle -- Questions Answered
see point 4
Interesting link at Post 113!