How exactly would one go about writing a paper that proves a negative and then convince one's peers to review it?
You'd prolly get laughed at.
You could look for some real science though (which is not to say that pro-AGW research isn't science, just that the paper you're asking for specifically isn't).
Ordinarially you'd assume the null and then formulate alternative hypotheses in hopes of disproving the assumption.
In order to "prove" the null you'd have to eliminate all other hypotheses.
It's pretty clear that in respect to AGW theory there are still plenty of other hypotheses circulating that still recieve a lot of consideration from many highly regarded scientists.
If you've got the time and access to a few scholarly databases you shouldn't have any trouble finding more than your fill of peer reviewed papers that "prove" something other than A is causing GW or which "prove" that existing theories explaining AGW are insufficent.
The best you can say at this point is that AGW has neither been proven nor disproven and I think that's where I come down on the issue (though I'll admit that I'd agree that humans have to have something to do with it, though certainly not everything).