"we only get to play this game once" - a quote from the video below that's created a great deal of interest on YouTube. At the time of writing, it's been viewed over half a million times over the last 6 months and has over 4,400 comments.

The video no special effects, no dramatic images and no well known actors. It was created by 38 year old high school science teacher Greg Craven from Independence, Oregon, who describes himself as "A high school science teacher in the process of burning out.

Greg believes that arguing over whether or not humans caused global warming is pointless and through a simple whyteboard exercise demonstrates that the risk of not acting far outweighs the risk of acting on the issue of climate change.

For example, the "extreme" of acting on climate change is a global economic depression caused by the cost of addressing the problem and accompanying regulation. But the extreme of not acting is far worse - not just a depression, but wars, famine, drought, fire, pestilence, disease etc. etc. etc. The video is more about problem solving and risk management rather than science.

I think it's a great video to show skeptics and people who are undecided on the issue  - if anything, just for a different point of view, without the politics and technobabble.. but with the occasional touch of humor.

It just goes to show, sometimes you don't need a big budget and whizz-bang effects to get a message across and just how powerful a medium the Internet can be in activism.

So, without further ado, presenting "The Most Terrifying Video You'll Ever See"

Greg also created a follow up.. complete with umm.. rather cheesy special effects and the introduction of a character called "Devil's Advocate". It recaps on the concepts of the first video and introduces some additional points for consideration - entertaining, yet thought provoking.

"How it all ends":

At the risk of making light of such a serious issue, it seems Al Gore has some serious competition :)