Geoscience Reference
In-Depth Information
of the Earth System, and therefore that the cumulative behaviour of
individual ecosystems can have knock-on effects on all of the planet
'
s
ecosystems.
35
Rockström and his colleagues recognise this relationship by including
land-use change and rates of biodiversity loss amongst nine
'
planetary
boundaries
which must not be crossed if the Earth is to remain in a
safe operating space for humans living on the planet.
36
They argue that
the crossing of thresholds could move Earth out of the Holocene era, a
period of relatively benign environmental conditions that has prevailed
during humanity
'
'
s evolution, into the less hospitable domain of the
.
37
Land-use change and biodiversity loss are described
as local/regional scale processes that could become of global concern
where the aggregate impacts of deteriorating ecosystem function increases
the likelihood that other thresholds at the global scale will be breached.
38
For example, deterioration in the capacities of ecosystems to absorb carbon
reduces the threshold for greenhouse gases that humans can emit into the
Earth
'
anthropocene
'
s atmosphere without triggering potentially catastrophic change.
The relationship between ecosystems and Earth System processes
adds a further layer of complexity to assessing the effects that human
activities may have on ecosystem functionality. It means that we must
be mindful not only of possible impacts on particular ecosystems when
assessing the cumulative effects of activities, but on all ecosystems due
to feedback effects from global change.
39
Unfortunately, we are no more
able to predict how deterioration in ecosystem functionality could affect
processes at the planetary scale, or how this may affect ecosystem func-
tionality in turn, than we are able to identify how ecosystems themselves
may react to disturbance. The degree to which a collapse in ecosystem
functionality may be required before this starts to have a global effect is
not known.
40
Planetary systems also display non-linearity in their beha-
vioural patterns, with the study of them being described by Boardman as
'
35
Ibid
., pp. 24
-
35; Chapin III et al.,
'
Terrestrial Ecosystem Ecology
'
,p.11.
36
J. Rockström et al.,
'
A Safe Operating Space for Humanity
'
(2009) 461 Nature,472
-
5;
J. Rockström et al.,
'
Planetary Boundaries: Exploring the Safe Operating Space for
Humanity
'
(2009) 14(2): 32 Ecology and Society.
37
Ibid
.SeealsoW.Steffenetal.,
'
The Anthropocene: Are Humans Now Overwhelming the
Great Forces of Nature?
'
(2007) 36 Ambio,614
-
22.
38
Rockström et al.,
'
ASafeOperatingSpace
'
,473
-
4; Rockström et al.,
'
Planetary
Boundaries
'
,under
'
Categorizing Planetary Boundaries
'
.
39
Rockström et al.,
'
ASafeOperatingSpace
'
, 474
-
5.
40
Rockström et al.,
'
Planetary Boundaries
'
,under
'
Rate of Biodiversity Loss
'
,
'
Land-system
Change
'
and
'
Discussion
'
.
