[MortMan]

It's those pesky unknown unknowns that get ya every time!

[Reform4Bush]

True, but one of the global warming skeptics claims is this (from Wikipedia: Global Warming Controversy):

Estimates at CO2's effectiveness as a greenhouse gas vary, but are generally around 10-100 times lower than water weight for weight, leaving a "net" greenhouse effect of man-made CO2 emissions at less than 1%.

So their vague statement would still stand as 'true' if human induced global warming only contributes 1%.

This is a completely non-conclusive report that is being spun to overstate human influence (as I suspect you would agree - just making the point for others to see).