CO2 is the exhaling breath of our civilization, literally... Changing that pattern requires a scope, a scale, a speed of change that is beyond what we have done in the past.

There is an air of unreality in debating these arcane points when the world is changing in such dramatic ways right in front of our eyes because of global warming.

I'm still trying to figure out exactly what President Trump represents in American politics. But, if nothing else, he represents a way for tens of millions of people who were desperate for change to just turn the table over and say, we want to start over again. But it is a challenge for our democracy. It definitely is. But, again, the remedy has to be devoting enough attention to restoring the way we make collective decisions in this country.

We have arrived at a moment of decision. Our home - Earth - is in grave danger. What is at risk of being destroyed is not the planet itself, of course, but the conditions that have made it hospitable for human beings.

I've been dreaming of this moment since I was a kid growing up in Tennessee: that one day, I'd have the chance to come here to Madison Square Garden and be the warm-up act for Elvis.

Humankind has suddenly entered into a brand new relationship with our planet. Unless we quickly and profoundly change the course of our civilization, we face an immediate and grave danger of destroying the worldwide ecological system that sustains life as we know it.

We're all capable of mistakes, but I do not care to enlighten you on the mistakes we may or may not have made.