Okay I'll try to put this as simply as possible...
It can't contribute to global cooling because the suns rays are bounced off the Earths surface into the upper atmosphere. Under normal conditions this energy (except for a small amount) would return to the spacial vaccum from whence it came. However a growing amount of light and heat energy are being trapped by greenhouse gases in the Earths atmosphere. The amount of light and heat energy which hits the Earth surface is constant. Greenhouse gases do very little to prevent the suns rays
entering the atmosphere for a number of reasons. It's mainly due to the nature of the sun as an energy source, the way that energy enters the atmosphere and the way it reflects off the Earths surface.
In other words it's not a two way street. Light gets trapped leaving the Earth not entering it. Like a drunk man and a phone box, it has no problem getting in, it has trouble getting out.
Think about it like this... Sun to Earth = straight line. Earth to space (because of the Earth surface being spherical) = hundreds of different angles. Essentially it is much easier for energy to travel through the Earths atmosphere in a straight line.
There has always been global warming for many millions of years. It's doubtless the reason why we can actually suppourt life however it has remained at a constant level until human interference. This is the reason why a few fractions of a degree over a decade or so is so important. The global temperature has not changed any more than a degree for hundreds of millions of years.
That's my basic rundown of my understanding of the phenomena.
No legitimate scientists have come up with any evidence suppourting the theory of 'global cooling' for about thirty years except for those working for conservative think tanks, which basically just find evidence to suppourt the theories they're told to suppourt.
So at one time the scientific community did theorise global cooling but this is how the sciences work. Ideas are theorised and then scientists find evidence to either suppourt or disprove their theory. The political interests claiming that the scientific community is backflipping in order to drag down the scientific communities credibility is ridiculous. Almost as ridiculous as claiming there's some liklihood of the Earth being the centre of the universe. Just because it was once theorised does not make the now proven fact any less conclusive.
Have you been listening to Alan Jones by any chance and/or reading the Daily Telegraph. I know they have publically embraced the skeptical 'global cooling' argument.
