Dead bodies .... like thousands or even millions of dead bodies rotting in the streets will be the only motivation the world will need in order to react to global climate change.
Don't get carried away with this ... I don't mean for anyone to go out and kill people. What I'm saying is that the world won't take any of this seriously until global climate change affects the world so much that thousands or millions of people start dying.
In the meantime, everyone will ignore the warning signs.
We aren't a very smart species, especially when it comes to global events that take decades to occur. We're like squirrels, you need to place a peanut in front of us in order for us to react.