Greenhouses gasses are a real phenomenon, we have released loads of CO2 and it has certiainly played some role in the warming climate.

That being said, the climate models are dubious, and their have been plenty of dire predictions that didn't turn out to be true (on the correct timeline), which does significant damage to the cause by impugning the credibility of things that are true. Yes the icecaps are melting, no they weren't gone by 2010, the alarmism backed by studies that imbue their work with ideology rather than remain objective, by blurring the lines between established fact and educated guess, have done immeasurable damage to the cause