The critical piece of global change evidence that is being ignored (because it is perhaps a bit more difficult to understand) is the rate of CO2 production. The best analogy I can make is that we're traveling down the highway, we're still under the speed limit, but the accelerator is to floor and it is stuck. We need to unjam the throttle, lift our foot off the accelerator and step on the brake before we are way over the limit and traveling at a speed that guarantees a fatal crash.

Warmer here, colder there, none of that matters. What someone conjectured thirty years ago is entirely irrelevant. Science improves with time, but predicting anything that is outside of your actual data set is always fraught with problems. The error bars on climatological data were so large thirty years ago that meaningful prediction was just this side of witchcraft, that's not so today. There is no doubt amongst the science community that on average things are warming up and that clearly observable phenomena correlates with anthropogenic CO2 production. All the details are not known, and hopefully never will be known, for the only way to know them in complete detail is to actually change the climate significantly. Enough data is in that most all scientists feel that we need to take the question seriously.