"But the scientists understood that it was serious, and science journalists passed along their predictions of sea-level rise and other problems. (Later research confirmed the predictions. For example, a 2004 study estimated that a rise of 3°C sustained over centuries would suffice to melt the Greenland ice cap and put the world’s coastal cities deep under water.)"Gloomsday Predictions Have No Fault" was how Science magazine summarized the report of one authoritative review panel. The report was noticed even by the New York Times, although only deep on an inside page.(76)"

The above is from an excellent series of articles The Discovery of Global Warming by Spencer Weart. I came on it while hunting for a trustworthy resource on whether there is / should be an "upper limit" on the temperature effects of raising CO2 / Methane levels in earth atmosphere. No luck (literally) so far.

If one reads all the (huge) articles on the site, they will find authoritative answers to almost all issues discussed here on GW / GHG. That Greenland Icecap melt amounts to approx. 30 ft rise in sealevel. Granted, "Centuries", but it's a far cry from what many on these threads have said, eg. "Nobody's predicting entire icecap will melt".

Nobody is predicting the Greenland Icecap will melt.

Even over CENTURIES.

Arthur

"For example, a 2004 study estimated that a rise of 3°C sustained over centuries would suffice to melt the Greenland ice cap and put the world’s coastal cities deep under water"

So, Arthur, are you claiming that "No-one predicts a 3 degC temp rise?" (definitely wrong), or that the above statement is wrong (proof?)

I believe this graphic represents the consensus ...

http://images.wri.org/climatescience_greenlandicesheet.jpg

i.e., it would require +7.3°C sustained over 3000 years to melt the Greenland ice sheet. The current IPCC report puts climate sensitivity at between 1.5 and 4.5°C per CO2 doubling. A 7.3°C rise thus requires a sustained CO2 level between 600 and 1800 ppm. The most recent Bangkok discussions talked about a target in the range of 445 to 710 ppm for 2100.

However, I don't think the fossil fuel inventory is sufficient to sustain that level for 3000 years - CO2 has an atmospheric residence time of between 50 and 200 years before it is stored long term in the deep ocean - and it is very unlikely that we will take no action at all during that time, especially since evidence will presumably mount in the coming decades.