[Geof]

... According to this study, in the last big global warming event 169,000 years ago) where the mean temp of the earth went up 9 degrees, the majority of this ice sheet stayed intact and didn't melt. I didn't listen to carefully to the report, but it was based on DNA analysis of organisms trapped in the glacier and using that to identify the organisms and then extrapolate back to how thick the glacier was when they were trapped....

Yes I read that one.

The "soot" bit I have read about and I think it is not soot but things such as sulfur dioxide which can cause high level haze. As far as I can gather reading different sources there is disagreement whether this cause cooling or warming.

martinw; It sounds like the Wiki people are getting a bit carried away...they do sometimes. Here is the simple minded meaning I am using; "The term albedo (Latin for white) is commonly used to applied to the overall average reflection coefficient of an object". Viewed from above, on average, clouds are whiter than ground and they scatter back incident radiation. There is controversy, as I mention above, as to whether clouds are net warmers or coolers.