Because, history has told us time and agan, through brilliant scientific thinkers like DaVinci and Einstein, that continuously questioning the establishment and systems of belief, is just good science.

This questioning and curious attitude has resulted in huge new advancements in particle, astro and quantum physics. as just one example.

But questioning the current scientific establishment on global warming, gets you immediately shamed, silenced, marginalized, attacked, denigrated by some of the most intolerant and closed minded people on planet earth.  You are now branded along the same lines as someone who doubt millions died brutally in WWII.   Question the Catholic church in DaVincas, you're branded a heretic.  Sound familiar?  

So the actual question you want answered is, why do followers need to blindly follow and believers need to faithfully believe?   The over-the-top climate change alarmist crowd is no different in mindset and approach then DaVincis Catholic Church.