The findings of the report will be used by governments and international organisations to map out their own plans for climate change mitigation.
"The IPCC plays an incredibly important role in the political negotiations so people can point and say 'Look, this is what is going to happen in 50 years, these are the options available for us to take actions'," said UN Environment Programme spokesman Michael Williams.
The report's conclusions will play a key role in negotiations on the Kyoto Protocol, which will take place in December on the Indonesian island of Bali.
It will also influence world leaders when they meet face-to-face over climate change at the summit of the group of eight most industrialised nations (G8) in June.
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