Download Sustainability Science Seminar Emergent Properties of CHES

Sustainability Science Seminar
Emergent Properties of CHES
Student response: Cambridge
Student Presenters:
Leah Stokes, Jess Newman, Dominic Maxwell
Erin Frey, David Bael, Tara Grillos,
Lilli Margol, Suhyun Jung
November 1, 2010
Agenda
1. Conceptual Framework: Definitions of
emergence, resilience, vulnerability using
examples
2. The social science side of resilience /adaptive
capacity
3. Predicting tipping points and understanding
their effects on well-being valuation
1. Conceptual framework
Emergence
• Chapter does not define emergence
• Different definitions exist in the literature (e.g. Cunningham,
2001):
1)
2)
Informal definition: the “surprise” event or tipping point
A property of a system not reducible to the properties of its
component parts (vulnerability and resilience?)
1. Conceptual framework
Vulnerability
• “the degree to which a system, subsystem, or system
component is likely to experience harm due to the exposure
to a hazard.”
Resilience
• “the ability of an environmental system ‘to absorb change and
disturbance and still maintain’ its base structure and function,
including reorganization of the system.”
Question: How do these terms relate?
1. Conceptual Framework – Example 1
• Sahel
– Drought from 1960s onward
– Research questions: Regime shift? Human or
environmental cause?
Foley et. al 2003
1. Conceptual Framework – Example 1
• Sahel mechanisms
– Environment: climatic changes
in sea surface temperature,
driving precipitation changes
– Human: land-use change, local
deforestation potentially
amplifying the cycle
• Difficult to tease apart human and
environment contributions
How can we describe this system using the book’s
framework?
- Low resilience?
- High vulnerability?
1. Conceptual Framework – Example 2
• Fisheries economics
– Human and environment systems
operate at different timescales
– Economic incentives drive
towards “bionomic equilibrium”
– Human system dynamics (e.g.
fisherman have mortgages;
uncertainty about population;
political pressures) means nonoptimal harvest rate
1. Conceptual Framework – Example 2
• Fisheries biology
– Selective pressures from
fishing can change the
underlying genetics of the fish
population
– Can drive species (and industry
in CHES) to a tipping point
• Are these tipping points
emergent properties?
– Loss of resilience?
– High vulnerability?
Law, 2000
Question 2
Exploring the “human/social side” of CHES
•Social Resilience vs. Human Adaptive Capacity
•Social Resilience of CHES as Inherently Emergent
•Mangrove conversion and institutional resilience in
Vietnam
•Reconciling the way we view properties of
environment and social systems to describe and
measure emergent properties
Social Resilience and Human
Adaptive Capacity
“Social resilience” and “human adaptive
capacity” are often used interchangeably.
– Are they actually the same?
– Neutral terms?
– Time frames?
– Scale?
– Whose resilience? Whose adaptive capacity?
– Bounding?
Social Resilience
Social institutions (behavioral norms and
structures of governance) are subject to external
pressures/shocks from political and economic
change. The ability to absorb these changes
depends on social capital and the characteristics
of the local resource systems.
In a CHES, the buffer capacity of the social system to
absorb perturbations can’t be separated from the
characteristics of the environment system
Adger 2000
Example: Mangrove Conversion and
Institutional Resilience in Vietnam
The buffer capacity of social
institutions and norms to absorb
perturbations will not approach
tipping points as long as the core
functions of its resource base are
not perturbed beyond a certain
range. When the ecologic
resilience is overwhelmed, the
social resilience collapses.
Adger 2000
Social vs. Environment?
How we think
about…
Environment
Systems
Social Systems
Coupled Systems
Valuation
Species/population
level
Individual level
?
Adaptation
Evolutionary
Quick: choice,
decision-making,
free will
?
Resilience/Tipping
Points
Exogenously and
analytically
determined
Endogenous and
socially constructed
(ethics, knowledge,
attitudes to risk,
culture)
?
Adger 2009
Q3: Implications for policy
Or, now that we know about CHES emergent properties,
what do we do differently on Monday morning?
(1) Early warnings of a tipping-point
↑ Slowness of
recovery
↑Increased
variance
↑
Autocorrelation
Source: Scheffer et al. 2009:
Early-warning signals of critical transitions. Nature.
How plausible is this?
Advantages
- Doesn’t require
understanding of
underlying
mechanisms
Disadvantages
- Only works if there is
a gradual approach
to a threshold
- Requires long time
series
- Confounding trend in
perturbations – leads
to false positives.
- Also: political
plausibility?
Tipping points and welfare
(a) marginal analysis
U
1
Value
(e.g. ecosystem services)
xtp
x (eg forest cover)
2
Uncertainty over
tipping point
E[U]
3
Expected
value
x (eg forest cover)
Tipping points and welfare
(b) fundamental uncertainty
Analysis
- Structural uncertainty:
unknown probability
distribution of impacts
- This makes the expected
impacts the “expectations
of expectations”: fattens
the tails (Student-t
distribution)
- Increasing impact
dominates decreasing
probability
Implications
- Simulations are
misleading (Monte Carlo,
IAM)
- For climate change:
potentially greater effects
on CBA than the choice of
discount rate
- CBA “arbitrarily
inaccurate”
Prob.
Future growth under BAU
Source: Weitzman (2009) “On modeling and interpreting the
economics of catastrophic climate change”. Review of Economics
and Statistics.
Weitzman (2007) “A Review of The Stern Review on the Economics
of Climate Change”. Journal of Economic Literature.