I personally don't have very much of an opinion about global warming. If pressed, I will assume that it's happening and if left unchecked that its consequences may be disastrous...but I haven't done anything like the kind of meta-analysis that would be necessary in order for me to have an _informed_ opinion.
(For the record, I assume it's happening at least in part because the consequences of that assumption should lead us, in large part, to take actions that I consider to be a good idea anyway, e.g., slowing our consumption of nonrenewable resources and increased efficiency in a variety of contexts.)
Anyway, these are two essays on somewhat-opposed sides of the debate. Dyson's essay is particularly interesting because he spends a fair bit of it talking about the value of scientific heretics and heresies. He may have fallen a bit in love with being a gadfly, but I think that his basic point is sound. Worth reading, and quite readable.