The climate has changed many times in the history of earth. The difference this time is that the additional factor of human activity is pushing the change further and faster than ever before.
I think there have been examples of fear-mongering, exaggeration, dishonesty and opportunism. However that doesn't change the underlying fact that we are in trouble.
The thing that annoys me is the way that we are guilt-tripped into making the most trivial changes 'to save the planet' when the real causes are elsewhere. China and India make our contribution to global warming look insignificant. Sometimes it feels like turning up to help after an tsunami with a dustpan and brush.