It admits to areas of uncertainty -- notably solar forcing and cloud feedbacks, where its assumptions have not been validated in the real world, but by computer models. Further, it's based exclusively on the period 1976 to 2000, thus ignoring the factors applicable to previous temperature changes (see my earlier comments on this). Therefore, the report is not unambiguous (compare, for example, the certainty of the evidence for the smoking/cancer link), not empirical and not capable of independent replication. In particular, it fails to demonstrate empirically a link between adding further GHGs to the atmosphere and a dangerous increase in global temperature. And that's the link that matters. Robin Guenier Here, J SMITH, is another example of the IPCC report's inability to provide empirical evidence demonstrating that adding further GHGs to the atmosphere will cause dangerous global warming: It refers to "projections of future climate change". It's specific about this, making it clear that "projections" are not "predictions" -- so it doesn't even try to show that adding GHGs *will* lead to a dangerous increase in temperature. Yet that's the essence of what's required. Robin Guenier Here, J SMITH, is another example of the IPCC report's inability to provide empirical evidence demonstrating that adding further GHGs to the atmosphere will cause dangerous global warming: It refers to projections "for a range of SRES emissions scenarios". But these (from IPCC "Special Report on Emissions Scenarios") were defined in 2000 and were much criticised by economists even then. Yet here we are