Geoscience Reference
In-Depth Information
7
Compounding crises
Climate change in a complex world
Will Steffen and David Griggs
A Four Degree World is daunting enough when considering climate on its own,
but when considered in the context of other changes that are occurring at the
global level - relating to population growth and other changes in demographics,
resource availability, global geopolitics, trade, biodiversity loss and ecosystem
degradation, equity issues and many more factors - the probability of interacting
or compounding crises is likely to be very high. The increasingly tight connec-
tivity of globalized society increases the risk of such crises, as a shock in one part
of the global system can be propagated rapidly around the planet.
Such complex shocks are already occurring. Consider, for example, the global
financial crisis and the food price spikes of 2008 and 2011, with the latter
possibly contributing to the recent unrest in the Middle East, the so-called 'Arab
Spring'. In so far as climate change is a contributing factor, such shocks and crises
will only become more probable and more severe, especially if the temperature
rise reaches 4°C or more above pre-industrial levels.
Complexity and the human enterprise: the view from the past
Contemporary society is not the first in the history of humans on earth to
have faced compounding shocks or pressures. Earlier complex societies in the
Holocene also faced these - albeit not at the global level - and many of them
collapsed as a result. In many of the most well-studied cases, regional climatic
shifts due to natural variability were often a contributing factor (Costanza et
al., 2006). Examination of these societal collapses can offer insights into the
risks that contemporary society faces from climate change, particularly those
associated with a Four Degree World.
Two of the best known examples of collapses - those of the Mayan Empire in
meso-America and of the Akkadian Empire in present-day Syria - were linked
to unusually dry climatic periods that overwhelmed the resilience of these
societies (Cullen et al., 2000). The decline of the Roman Empire coincided with
the transition of the climate from the 'Roman Climate Optimum', a somewhat
warmer, drier and more stable climatic period at the height of the empire (300 bc
to ad 300), to one less hospitable and more variable (Gunn et al., 2004). Perhaps
the classic example of a climate-induced collapse was the disappearance of the
