denial is easy...
And Bolt is an afficionado - this is pretty much all he does (I refuse to dignify this man with a link). I wouldn't normally waste my time with him, but it bothers me that people actually believe him.
Global warming is happening - average global temperatures are increasing. (Do you know what an average is, Mr. Bolt?)
Here are some figures I dragged down from the Hadley Centre for Climate Prediction and Research
It is fairly obvious that global temperatures are currently increasing. This is what happens with global warming.
Update: Am on fire today, that is three graphs. That is really sad.