Mann's hockey stick graph (actually Mann, Bradley, Hughes 1999) has not been "debunked". It has been verified over and over and over again.
The concern of the world's scientists that human CO2 emissions were warming the planet predates Mann's graph by many decades.
Mann is currently director of the Center for Science, Sustainability & the Media at the
University of Pennsylvania. He does not live in an "eco bunker", whatever that's supposed to be.
Thousands of scientists have cited Mann's work - it is widely respected. You'd have to be "a real ignorant loon" to think otherwise.
He would have to get elected first and since 2016, he's done nothing but lose, so... I suspect the "green" movement will continue to exist for the foreseeable future. But, just out of curiosity, even if Trump were president, how do you think he could "kill" the green movement? Pronouncement? Fiat? Executive Order? Sic Seal Team Six on them?