Spencer has contributed specific work in peer reviewed journals that is part of the scientific discussion, but his overall opinion on climate change is motivated more by his own religion than anything else. He's both sympathetic to intelligent design and signed a statement which said among other things ""Earth and its ecosystems – created by God's intelligent design and infinite power and sustained by His faithful providence – are robust, resilient, self-regulating, and self-correcting."
http://en.wikipedia.org/wiki/Roy_Spencer_(scientist)#Climate_change Essentially he believes that climate change isn't happening because his religion won't let him. Note how that statement wasn't even just about climate, but about ecosystems as a whole. Christy doesn't seem to have that same sort of underlying motivation and might make more sense to pay attention to, but in this context, the vast majority of experts disagree with both of them, and when dealing with complicated scientific issues, using expert consensus is a useful heuristic, that's before we get to the serious issue that not only is the expert consensus clear, it is a consensus about some very bad results, not just a consensus about an issue which doesn't have substantial impact.