The more respected global warming papers have been published and accepted in peer reviewed journals. Point out any global warming denialist papers that have done the same. I think the most you'll find are papers that suggest global change could result in positive things in some areas. I don't know of any saying that climate change is not happening.
The problem with this argument is the climategate emails themselves were said that they were not allowing anti-global warming papers to be in peer reviewed journals ("will keep them out somehow — even if we have to redefine what the peer-review literature is!"), so saying they the no man made global warming argument is invalid because because it isn't in peer reviewed journals isn't really a fair argument.
Mirrors should reflect a little before throwing back images. -- Jean Cocteau