The following comment by Paul Williams provides a different perspective on the question asked by Walter Starck a couple of days ago.
"I think we argue over AGW because there's so many unanswered questions, such as:
1. Where are the climatic catastrophes we've been hearing about?
2. Why are the AGW proponents using dodgy statistics to bolster their case? (Even though they've now "moved on")
3. Why are they proposing ineffective "solutions" for climate change, such as Kyoto?
4. Why do they constantly say the debate is over, when it obviously is not?
5. Why do they attack their opponents, rather than their opponents arguments?"
John Quiggin,
Re your points that:
"For the 20th century as a whole, most models suggest that greenhouse gases actually drove more warming than was observed, being offset by human-generated sulphate and other particulates. Combining the two offsetting effects gives a good fit to the observed warming, so the best point estimate answer for Robert's question is 100 per cent."
and
"The upward trend for C20 as a whole can be explained entirely by the net impact of anthropogenic forcings."
Do you have any scientific references for your conclusion? In particular, has the IPCC ever drawn it, and if so, where?
Also, when you say that the upward trend for the 20th century can be explained entirely by the net impact of anthropogenic forcings, can that trend also be explained otherwise?
GIVEN the answers above, no one knows what physical factors influence climate.
Anyone who does, needs to be, initially, catergorised differently.
Jungle fever - a variant of global warming fever?