Zamzara wrote:
For example the water vapour thing: this is not scientifically correct* and has been widely debunked, yet is is still circulated as the "Number 1 thing the scientists don't want you to know about."
* Water vapour is in a natural equilibrium. Adding more doesn't cause a long term increase in level, because the atmosphere cannot hold more water so it falls back as rain. Adding CO2 does cause a permenant increase in level, so it's not comparable.
Hang on a moment!
CO2,
by itself, cannot cause more than a barely significant rise in global temperatures. This has been known for more than a century now. The IPCC calculated that a doubling of CO2 levels from pre-industrial levels would, by itself, lead to a temperature increase of 0.6 to 1.2 degrees - which was why it was regarded as a non-issue for so long.
The 'enhanced' greenhouse theory, which is what all the hoo-ha is about, goes something like this: CO2 creates a small increase in atmospheric temperature, which in turn leads to more water vapour (warm air holds more vapour) which, being a far more potent 'greenhouse' gas than CO2, leads to vastly more warming.
Note that it's
they that say that water vapour is important.
What they don't say is that, with the amount of water vapour
currently in the atmosphere, average global temperatures should be almost 80 degrees! The fact that they're not means that water vapour really is a potent feedback mechanism - but a
negative one, not a
positive one.