For Starters: In short, Global Warming is the heating up of earth, so that it can't support life or present human form.
Not so real (frighting) as of today, in nature everything takes time.
 

Unless, written otherwise on the label :
A baby takes 10 months to be born. But corporations can be formed overnight.
However advanced the technologies may be, it still takes the same amount of time [with nature].

We still have

 time... as the most intellegent species on the planet, we have time...

The threat is very real. Nature often seems slow, but may prove fatal, if we don't act. 

Resources:

1. en.wikipedia.org/wiki/Global_warming

2. for a more interesting timeline here: www.nytimes.com/interactive/2009/12/07/science/20091207_CLIMATE_TIMELINE.html

3. and here Climate Change Background

Documentaries:

1. An Inconvenient Truth

2. The 11th Hour

3. Documentaries in BBC, and other channels