"Earth’s climate is now changing faster than at any point in the history of modern civilization [1], primarily as a result of human activities [2]."

Can someone help me to understand [1] and [2]? I'm a pretty smart guy and I want someone to plainly explain to me how climate change works. No bullshit. Please keep away from "WELL EVERYONE SAYS SO" type comments. I want to know

1. What is meant by climate change
2. Why it is changing "now more than ever before"
and
3. Why it is a result of human activity.

inb4 CO2 comes out of the ground CO2 makes things warm so we make things warm Q.E.D.

I'd prefer ironclad statements. I am really tired of how political everything is.

>WHAT HOW CAN YOU BE SKEPTICAL?
Because I'm not a fucking retard and I deserve to know how things work.