[Hulme] I do not believe we have any sure basis for establishing what a 'non-dangerous' level should be. This is so for several reasons: - what is 'dangerous' depends on what measures are taken to adapt to climate change. 550ppm may be 'safe' in one assumed future world but 'dangerous' in another. - the concept of 'danger' is not one that science can pronounce on. Such a level has to be negotiated via a social and political process. This negotiation has also to take place in the context of other risks that society is exposed to, i.e., we may be prepared to run a higher risk with climate change if it means we can divert greater resources to reducing global poverty. - the basis for establishing 'danger' is contested.[Matilda Lee] We are aware that there is currently no consensus within the scientific community on what an appropriate level for atmospheric concentrations is.
[Hulme] Indeed not - and there never can be. This question is not appropriately answered by science - it has to be answered by society! This is a very important point to get across.
AR5 - the Synthesis Report
43 minutes ago