Geoscience Reference
In-Depth Information
Scales of Space, Time and Organisation
Complexity research also complicates accepted notions of geographical scale. Spatial
scale is most commonly treated as a nested hierarchy in which areal extents act as
containers for those at a smaller scale level and are themselves encompassed by a
single container at a larger scale level (Haggett, 1965). A single watershed may
contain multiple reaches and may itself be contained by a larger watershed hemmed
in by continental divides and oceans. Nested hierarchies assume that all the com-
ponents at one level, such as river reaches, fi t completely within a single component
at a larger scale, here, a watershed. In this spatial hierarchy, the effects of an event
at the local level work their way up to larger levels, but their impact is vanishingly
small, as when a single drop of water works its way from a single subwatershed
through its encompassing regional and continental watersheds.
Scale becomes less straightforward in the face of deterministic complexity. Sen-
sitivity and non-linearity ensure that local actions can have disproportionate effects
at larger scales. Instead of being dampened out, small changes may become ampli-
fi ed through the non-linear interactions among components across scales. This can
occur in purely physical systems, as when we see the butterfl y effect noted above in
climate systems, or in human-environment systems, as when environmentalists use
iconic imagery, such as polar bears facing extinction, to skip over regional and
national political arenas to discuss climate change on the world stage (Slocum,
2004).
Emergence and supervenience result in dynamic system structures. Some ecolo-
gists argue that scale levels in an environmental system should not be seen as fi xed,
but instead, should be defi ned by interactions and relationships among entities
(O'Neill, 1988). Complexity adds the notion of emergence to the mix by positing
that scale levels are emergent phenomena that arise from interactions among entities
as when institutions and organisations emerge from the interactions among indi-
viduals (Ostrom, 2005). For example, ecological landscapes are usefully treated as
complex systems composed of interactions among human and natural actors that
generate multiple scales of analysis (Easterling and Kok, 2002; Bousquet and Le
Page, 2004).
Complexity research also contributes the concept of scale invariance, defi ned as
a single process or pattern that is identical across spatial or temporal scales. Fractals,
for example, are scale invariant because their appearance does not vary with the
scale at which they are observed. As noted above, invariant patterns such as fractals
may indicate that processes giving rise to their existence may also be similar across
scales (White and Engelen, 1993; Marquet, 2000). These processes in turn are often
of interest to complexity scientists, such as self-organisation, self-organised critical-
ity and emergence (Prigogine and Allen, 1982; Bak, 1996; Lee, 2004; Crawford,
2005).
Given the emphasis on how systems emerge or grow from the bottom up, there
is less research on how systems evolve when the components are conscious of their
own part in the wider system. Research on how social norms emerge from interac-
tions among people, for instance, is often emphasised at the expense of understand-
ing how these emergent norms affect the people themselves in turn (Ostrom, 2005).
Some defi nitions of emergence, particularly in the natural sciences, posit that
constituent elements are unaware of the role they play in creating emergence in a
system (Forrest, 1990). This approach to emergence may not adequately refl ect the
