Global warming was hard to prove even the UN IPCC climate report keeps saying the hockey stick effect that was to begin in 1990 is on "pause" but doesn't say anything more. 

Hence, global warming was rebranded as climate change to change the channel and deflect scrutiny.

The scientists who challenge to findings are branded as deniers and shamed into silence and tow the party line.  He who screams the loudest wins approach. Yet this undermines the basic of science to put the findings to scrutiny. The scientist can't predict the weather 1 month from now but can accurately predict the temperature 10, 20, 50 years out...and scientists have always been right and never wrong.  The planet has been warm in the past as ancient forests have been found in Canada's artic...also caused by man.