reversing the unsustainability spiral guido van hofwegen, gertjan becx, joep van den broek and niek...
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Reversing the unsustainability spiral
Guido van Hofwegen, Gertjan Becx, Joep van den Broek and Niek Koning
A modeling study of the co-evolution of population, techniques, natural resources and
institutions of an agrarian subsistence economy
Outline
1. Recapitulation of poverty spiral
2. Agent Based Modeling.
3. Overview SUBSA model
4. Issues related to (agent based) modelling
5. Conclusions
Africa struggles with economic-demographic-environmental vicious circles in its rural areas
We hypothesize that the dynamics in Africa are comparable to those in pre-industrial Europe:
population growth
prices moderately
high
population growth
prices moderately
high investment in sustainable
intensification
population growth
prices moderately
high investment in sustainable
intensification
population growth
prices skyrocketing
investment in sustainable
intensification
impoverishment
population growth
prices skyrocketing
investment in sustainable
intensification
soil degradation
impoverishment
population growth
prices skyrocketing
investment in sustainable
intensification
soil degradation
impoverishment
population growth
prices skyrocketing
investment in sustainable
intensification
soil degradation
impoverishment
distrust, conflict, paranoia
population growth
prices skyrocketing
investment in sustainable
intensification
soil degradation
impoverishment
distrust, conflict, paranoia
population collapse
prices skyrocketing
investment in sustainable
intensification
soil degradation
impoverishment
distrust, conflict, paranoia
population collapse
prices collapse
soil degradation
impoverishment
distrust, conflict, paranoia
population collapse
prices collapse
soil degradation
impoverishment
distrust, conflict, paranoia
fall-back on extensive
techniques
population recovers
low prices
extensive techniques
population growth
prices recover
extensive techniques
population growth
prices moderately
high
extensive techniques
investment in sustainable
intensification
A vital element in these dynamics was an endogenous relation between population and prices.A continuous availability of cheap food the last decades locked Africa in a unsustainability trap.
population recovers
low prices
extensive techniques
Cheap food imports
population boom
prices remain low
extensive techniques
Cheap food imports
Getting out may not be as simple as rising price levels as the situation is embedded in Africa's institutions at all levels.
To elaborate and test the previously explained vision for the African context and explore its ramifications.
Objective
To reach the objective we need a model that can handle the co-evolution of
population, natural resources, technology and social strategizing at
local regional and global scales.
Agent Based Model (ABM)
“In agent based models agents are described as unique individual and autonomous entities
which have a goal and base their behavior on adaptive decisions” (Grimm 2003)
ABM continued
• Agents described as unique and autonomous individuals
• Agents: – Are all different– Have a life history – Interact with other individuals – Make decisions which are adaptive and depend on
the individuals and environments state – society emerges from their behavior
A simple example
Why Agent based modeling in this context?
• Allows for interdisciplinary (combining actor approaches with system approaches)
• Allows for local decisions• Bottom up dynamics• Inclusion of multiple levels
SUBSA model
• Highly abstract• Decision making agents are farmer groups.• Long time period (hundreds of years)
IT IS NOT:• A spatially explicit simulation of reality
Model levels
Resource base
Decision making level
Macro institutional /environmental level
Soil and crop
Farmer groups
In this case: world market price setting
mechanisms.
agentsFarmer groups
Goal seeking
Which are
Represent
two yearutility maximizing
Free time
income
Yield of own plot
Result from trade
Result from robberies
Utility year 1
Utility year 2
Discount rate /
Time preference
Driving force behind agent behaviour
Agricultural Production
Agricultural production
inputs
capital
labour
land quality
population
free time
Room for consumption and investment
Weighting of current consumption against future harvests
Technology
consumption
Agro ecological production landscape
Time preference / discount rate
Input
Output
Resource Dynamics
Resource dynamics
Land quality
Short term inputs
Is a broad concept
Long term inputs
jeopardize
enhance
Mix of inputs depends on time horizon
Strong direct yield effect
Yield effect indirect.
Technological
Change
Technological change
Memory of production technologies
Most suitable technology for production
Depending on:Labour availabilityCapital availabilityLand quality
All related to time preference!
Each groupowns
Technologies are forgotten
When not used longer than a certain period
Technologies can be imitated from neighbours
new technologies Experimenting
if expected future profit is high
enough so depends on time preference
again!
Removes “ladder” from poverty trap
Trade & conflict
Each group
Can
Live inautarky
trade
World market
Other groups
Differences in labour and food availability
Food for labour
World market price
Depending on
Cooperation (trade) & conflict
Can result in robbery
Implemented as:
No pay, or take double the
salary.
Increases future transaction costs
Transaction costs
Conflict history distance infrastructure
Validation
How to improve the validity of an abstract agent based model that runs at long time scales?
Earth testimonies
Earth testimonies II
Desk / Field studies
• Choice making behavior
• Interaction between trust agricultural development and migration.
Conclusion
© Wageningen UR
•Models are always wrong
•Multi agents models can help in acquiring insights on multiple scale multiple driver phenomena
•These kinds of models contribute to integrated studies with a long term view
• Extra attention has to be paid to creative methods of validation