The problem is essentially that those making statements and forming the "consensus" are almost invariably speaking outside their area of core competency. The glaciation people say "sea level is rising because it is warming, the major ice sheets are not mass balance negative". The ocean temperature studiers say "sea level is rising because the ice sheets are melting, the ocean is not getting meaningfully warmer", and the sea level rise analysts say "I don't know what those guys are talking about, global mean sea level is not meaningfully rising". It's a room-full of people saying "I got nothing, but HE does".

(sea level)
http://epic.awi.de/epic/Main?static=yes&page=abstract&entry_dn=Chu2001a
"Based on the few very long tide-gauge records, the average rate of sea-level rise has been larger during the 20th century than the 19th century.
no significant acceleration in the rate of sea-level rise during the 20th century has been detected."

(ice sheets)
http://www.sciencemag.org/content/297/5586/1502.abstract
"Recent advances in the determination of the mass balance of polar ice sheets show that the Greenland Ice Sheet is losing mass by near-coastal thinning, and that the West Antarctic Ice Sheet, with thickening in the west and thinning in the north, is probably thinning overall. The mass imbalance of the East Antarctic Ice Sheet is likely to be small, but even its sign cannot yet be determined. Large sectors of ice in southeast Greenland, the Amundsen Sea Embayment of West Antarctica, and the Antarctic Peninsula are changing quite rapidly as a result of processes not yet understood."

(thermal expansion)
http://epic.awi.de/epic/Main?static=yes&page=abstract&entry_dn=Chu2001a
"We present new estimates of the variability of ocean heat content based on: a) additional data that extends the record to more recent years; b) additional historical data for earlier years. During 1955-1998 world ocean heat content (0-3000 m) increased 14.5 × 1022 J corresponding to a mean temperature increase of 0.037°C at a rate of 0.20 Wm-2 (per unit area of Earth's total surface area)."

(Note from this one that .037C is enough to account for the baseline sea level rise that has actually taken place).


It goes on like that,
http://www.climatechangefacts.info/ClimateChangeDocuments/LandseaResignationLetterFromIPCC.htm
The foremost hurricane researcher resigning from the IPCC over the statements of an IPCC spokesman blaming Katrina on AGW.

Furthermore, much is made of the AOCGM climate models. Models with 1 year timesteps, resolution sufficiently coarse to miss the very existence of everest, that do not include *any* terms for solar output variability, milankovich orbital variation, vegetative response or cloud formation/reduction. Those models are able to "hindcast" only over their calibration years, the years in which the factors have been "fudged" to *force* them to "predict" accurately over those years. 1 year before or after their calibration years, and their projections are not more reliable than outright guessing. Not only that, but a model by definition is not evidenciary, that *isn't what they do*. what models are for is saying "if our thoeries are correct, this is what should happen", and determining the responses apropriately.

As an example, here is a graph showing actual temperature versus the "predicted" temperature from the IPCC AR1 report (1990)
http://icecap.us/images/uploads/SPPI8YR.jpg
Rather different aren't they? I also gave you the same graph for the AR3 in the other post.

Each and every aspect is the subject of similar levels of debate on the most basic science. This is why I remain *unconvinced*, agnostic, not atheistic. The science is simply not there to support the statements that keep getting made. That said, co2 is a radiatively active gas, so there is no doubt that releasing it will have impacts.