Geoscience Reference
In-Depth Information
occurrence becoming apparent only after the event and with lengthy
scienti
c debate being required to reach a consensus on why the shift
may have occurred.
62
Even if key variables and thresholds are known, systemic conditions
may afford little or no evidence that change is imminent.
63
Some recent
research challenges the view that the imminence of regime change
cannot be recognised by suggesting that changing dynamics as a system
approaches a threshold could provide an early warning of this.
64
However,
the value of that information, whilst it may allow an urgent precautionary
response, is questionable in other respects. It does not provide any indi-
cation either of where the suspected threshold lies or of how close the
system lies to it.
65
In addition, it assumes that socioeconomic systems will
be able to respond to a warning with suf
cient speed to prevent a change in
state from happening.
66
This may be possible if the causes of change are
identi
able and can be halted quickly. However, it may not be possible
where the causes of movement towards thresholds cannot be established
or where this is being driven by activities in which substantial sums have
been invested, that use infrastructure with large upfront development costs
and a long-term lifespan, and that have become embedded in national,
regional and local economies. These considerations place the emphasis on
the initial decision rather than waiting on evidence of a potential environ-
mental disaster before acting.
67
Second, the complexity of ecosystems and our poor understanding
of them present obvious risks that the use of targeted interventions to
bolster some speci
c aspect of their resilience may itself create risks of
failure. Writers on resilience criticise managerial approaches that seek to
maximise an ecosystem
'
s productivity by reducing its vulnerability to
some speci
c disturbance (e.g., through the use of pesticides) because
this tends to make them vulnerable in other respects by preventing
natural cycles of change from taking their course.
68
In the same way,
risks arise that the manipulation of an ecosystem to make it more robust
62
Scheffer et al.,
'
Catastrophic Shifts
'
, 591, 595
-
6; Biggs et al.,
'
Turning Back
'
,826;
Carpenter,
'
Ecological Futures
'
, 2074, 2080
-
1.
63
Scheffer et al.,
'
Catastrophic Shifts
'
,591;Biggsetal.,
'
Turning Back
'
, 826.
64
Biggs et al.,
'
Turning Back
'
,826;WalkerandSalt,
'
Resilience Practice
'
,p.86.
65
Biggs et al.,
66
'
Turning Back
'
,829
-
30.
Ibid
.
67
See also Chapter 2,
Section 2.3.2.2
.
68
Walker and Salt,
'
Resilience Thinking
'
, pp. 5
-
8; Gunderson,
'
Ecological Resilience
'
, 432
-
3;
C. S. Holling,
'
inW. C. Clark and R. E. Munn (eds) Sustainable Development of the Biosphere (Cambridge:
Cambridge University Press, 1986), pp. 310
'
The Resilience of Terrestrial Ecosystems: Local Surprise and Global Change
-
11.
