I don't know if a roulette wheel will pay out on the next spin, but I DO know how fast I'll lose money if I continue to put my money down on black.
That's the difference between weather and climate. You don't need to predict the next 5 day's weather to know that 100 years from now we're fucked if we keep pumping CO2 into the atmosphere... and we may be fucked even if we manage to reduce greenhouse gases dramatically in the near future.
The data HAS been verified. For instance, look at the Berkeley Earth Surface Temperature project. This was a project funded by right-wing activists who doubted the climate science. They specifically objected to use of satellite data and felt that terrestrial weather stations were not being vetted correctly. (For instance, showing pictures of temperature stations a few feet away from buildings or barbecues which they said tainted the results.) The Berkeley guys were led in part by Richard Muller, who has been a long-time skeptic. They went and got original raw data, and did a thorough job vetting each data point.
The result is that their data agrees completely with the climate change models. Muller's public summary is here: http://www.nytimes.com/2012/07...
There are other contrarian opinions, but very few of them work with large data sets in any honest way. Nearly all the contrarian viewpoints can be linked to right-wing money and other professional gains that their mainstream colleagues do not enjoy.
But mostly, the arguments they make are trash - which is why they aren't published. They're dumb ideas, easily seen through. Science works by honest appraisal of ideas and data, not opinion or groupthink as you seem to believe. It's not perfect - lord knows I disagree with a lot of scientific colleagues' approaches - but by and large good science tends to win out over bad science.