Implicit in the work of the IPCC, and almost explicit in the report released yesterday, is the overriding importance of how the world choses to develop in the future. In the analysis in the IPCC lies the inescapable fact that how the world chooses to develop, independent of how the world responds to climate change, will modulate future global per capita GDP by a factor of up to 4.7 (the differences between the lowest and highest in the IPCC storylines for the future). By contrast, how the world chooses to respond to climate change, independent of how the world develops, will modulate future global per capita GDP by a factor of 1.05 to 1.20 (i.e., the conclusions presented in the IPCC WG II and the Stern Report).
To put this another way, from the standpoint of global GDP decisions that the world makes that make one storyline more likely to occur than another are between 19 and 74 times more important than decisions that are made about greenhouse gas emissions, under the assumptions provided by the IPCC!
So long as the IPCC, the Stern report, and others use GDP as a metric to advocate action on climate change, then this result is unavoidable. This is the main reason why some people have concluded that decisions about development, otherwise known as adaptation, must be front and center in any discussion of climate change. Yet the IPCC continuously tries to deemphasize the importance of adaptation as development, for instance writing that,
there are formidable environmental, economic, informational, social, attitudinal and behavioural barriers to implementation of adaptation.
Of course the exact same thing could be said about mitigation (but is not said), and by contrast the IPCC always frames mitigation in a positive light:
Many impacts can be avoided, reduced or delayed by mitigation.
It is well past time that the community openly and forthrightly discusses the importance of development pathways as the primary determinant of the future welfare of people and the environment. Carbon dioxide should be a part of that discussion, but not a substitute for it. The IPCC WG II is a small step in the right direction, but there remains a long way to go.
The background and calculations which provide the startling numbers above can be found below.
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