"Reality has a way of hitting you in the nose, if you don't pay attention..." It's a quote that Barack Obama says to DiCaprio in the clip above and it couldn't be more on point.
I'am not the greatest activist on earth but I would never deny that we as humans do a lot that harms our planet. I always think of Agent Smith's quote from The Matrix :"Human beings are a disease". And I'd say yes, we are a disease to this planet in the sense that we destroy it more than we help it to flourish. So the message of climate change is to really take it serious and even if we can't phatom the implications (might they be 50, 500 or 5000 years in the future) they will hit us in the nose.