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Figure 7.5
The nine planetary boundaries and estimates of the current value of the
control variable compared to the boundary estimate
Source: Rockström et al., 2009
Hence, climate change is likely to impact disproportionately upon the poorest
countries and the poorest persons within countries, exacerbating inequities in
health status and access to adequate food, clean water and other resources. This in
turn may lead to large numbers of environmental refugees, something that is already
being seen in many places around the world from North Africa to Pakistan.
Again, just as there are tipping points in the natural system due to amplifying
feedback mechanisms, it is likely, if our modern society also behaves as a single
complex system, that elements within this system also have the potential for
tipping points where small changes in driving conditions can lead to large conse-
quences. It can be argued that the way the economic system behaved to create
the global financial crisis is an example of such behaviour.
As indicated earlier, one approach to dealing with complex interacting
environmental challenges is to define a safe operating space for humanity within
the Earth System based on a small set of planetary boundaries. In the same way it
may be possible to define a safe operating space for humanity within our modern
society by defining a set of sustainability boundaries. To date, because of the
complexity of the systems involved, this has not been attempted, but it may be
necessary if we are to understand how best to respond effectively to the threats
imposed by a Four Degree World.
