The issue needs to be addressed in multiple parts;
Is the climate changing?
If yes, is the cause man made?
If yes, to what degree?
The climate is changing and will always change, that's a given. It is affected by numerous variables most of which are out of our control eg. the sun, other extra-planetary activity, other "greenhouse gases" (i.e. not CO2), natural emissions eg. volcanoes, termites, cows etc. (although granted, livestock emissions would by default be considered man made due to the "mass production" of cattle).
If you hypothesise that human involvement has a direct impact on global warming it is as a part of these factors, so what effect do we have on this system? This is also based on the hypothesis that it is CO2 which is the primary contributor to the problem not other gases. This has not been proven except in mathematical models. There are no scientifically observed experiments to prove this is the case (to my knowledge).
Most of the information you read
will support Global Warming for one of two reasons;
1> (The cynical view) It is a good source of funding for scientists which is always difficult to come by. Wave a little green flag and the money comes rolling in, say the hypothesis is rubbish and be branded a puppy burning eco-terrorist.
2> (The less cynical view) It is the majority view, therefore most material as a matter of course would support this.
More material does not prove something is correct as has been shown time and time again. That is the beauty of scientific hypothesis/theory. It is constantly reinvented to accept new evidence. Global warming has become a closed system that ignores contrarian evidence therefore creating;
Scientists spurned and ridiculed for their evidence based ideas.
Scientists desperate for funding "making numbers fit".
People who have no ability to have an impact on their opinion either way (you and I) disagreeing over information that is sketchy at best, but there is more sketchy information available to support than undermine.
The media do not help this as they thrive on disaster and the good old Global Warming card is a nice one to keep at the back of the pack whenever things get a bit dull or need some extra pep.
I have never read, seen or heard anything that I would consider to be quantifiable method tested evidence in support of human caused global warming and until I do I am unlikely to change my opinion, however if anybody has anything they think fits this criteria I am more than happy to take a look and reassess my opinion.
And finally (sorry for the long winded post) that's what this has really become, an arguement about opinion. No one really seems to care anymore about the issue, just that they are the ones that are right about it, which is a little bit sad.
