Copenhagen

Battingozzy - The 'Copenhagen Accord' which emerged from the talks in December refers to the need to keep global temperature rise below 2C, but has no plan for how to do this, still less how to distribute the burden fairly.  Countries have now submitted voluntary pledges to reduce emissions under the Accord, but these are clearly insufficient.  The figures given in this Guardian article suggest that under a 'business as usual scenario, by 2100 global temperatures will rise 4.8C.  Even if the pledges are all fully met they will still rise 3.9C by 2100.  Although a 2C rise is generally seen as the 'safe' limit, even this would still have a devastating impact in some parts of the world.

http://www.guardian.co.uk/environment/2010/feb/12/copenhagen-carbon-emission-pledges

Does anyone know where these figures come from and whether the 3.9C figure is generally accepted?   Also, is there a clear, reliable summary anywhere of what sort of impacts are expected with a 2C, 3C and 4C global temperature rise? 

Thanks