When I saw AG on his lift, I was praying that THAT was the tipping 
point! :-) Wonder whether it's anything to do with Tipper!

The problem is that IF a massive positive feedback phenomenon occurs, 
the notion of a tipping point cannot be excluded. We know of several 
positive (and negative) feedback mechanisms but none of them, so far, 
seem likely to go beyond the path of no return. The permafrost release 
of methane clathrates may be the one that MAY present a higher risk in 
the relatively short term (say, 20-50 years), but the best modelling 
(albeit still primitive and incomplete) does not seem to deem it likely. 
What may be more risky in the long term - and no modelling has been done 
AFAIK - is the melting of submarine clathrates (CO2 and CH4) - in the 
next centuries as the lower sea levels warm. This is speculation on my 
part but the quantities of GHGs there are really phenomenal.

I suspect the term was used initially by the likes of Greenpeace, FoE, 
WWF and other extremist ecopolitical NGOs as part of their scare tactics.

Brian

MA/NY DDave wrote:
> Hi EnviroNetr's,
> 
> Over the last few TV News shows, I have heard journalists occasionally 
> mention "the tipping point" or "a tipping point" when discussing Global Warming.
> 
> I wonder if anyone knows who started this and when???
> 
> My only clue is that portion of Al Gore's film that got me mad for his theatrics, 
> hyperbole, by using a hydraulic lift to raise himself 6 plus feet to make a point 
> and make the audience groan for fear.
> 
> So does anyone know??
> 
> YiEngr, MA/NY DDave
> Yours in Engineering, Dave
>