Jet Stream & Climate Change

I do sometimes find myself in the strange position of having to dampen down the more excitable sections of the climate change brigade.
Just as climate change deniers try to challenge me on global warming after a few days of unusually cold weather, i hear the same thing from environmentalists when the weather pattern fits neatly into our idea of a changing climate.
With the wet summer that we are having, the southerly slipping jet stream is being held up by some people on my side of the climate change fence as proof that we are right but i wish they wouldn't just yet.
Despite looking, there is an absence of proof from the climatalogists and scientists who study these things that the jet streams unusual movements are due to climate change and if they don't know with all their sophisticated equipment and expert knowledge, how can we?
Until someone comes out and states either yes or no and here is the compelling evidence, it is best to just be honest and state that we just don't know yet however strong our suspicions.