One of the reasons it's difficult to dismiss Global Warming is because everything proves it.
Bitter, historic freezes? Global Warming
Mild, warm winters? Global Warming
Near record flooding? Global Warming
Severe Hurricane seasons? Global Warming
Mild Hurricane seasons? Well, not much, just ignore
Droughts? Global Warming
Floods? Global Warming
Record Highs? Global Warming
Record Lows? Global Warming
Near record anything? Global Warming
Severe weather? Global Warming
Mild weather? Ignore
Earthquakes? Global Warming
And on it goes. Basically whatever happens proves global warming. If it's the worst of anything in X years, it proves Global Warming. Never mind that this means X years ago it was just as bad. That doesn't matter. Just like it might or might not matter what the weather is outside your window. Sometimes it might prove Global Warming. Sometimes it might just be weather.
Sane people can distinguish. Clearly the climate is changing, as it always has since the beginning of the planet. It also seems to be getting warmer, as it has done at different times throughout the eons. And I seriously doubt that our approach to industrialization and technological innovation hasn't had it's negative side effects. Lesson learned: Be cautious about handing science and technology a blank check - you never know what the long term impact might be.
Other than that, most of the hysterics is based on believing the equivalent of a car salesman insisting that the oil slick under the car is supposed to be there.