25/03/2014
An Input-Output/System Dynamics approach to
ecological-economic modeling:
Interrelations between natural capital stock and economic growth
Mateo Cordier a, b, Takuro Ueharac, Bertrand Hamaided and
Jeffrey Weihe
a Centre
Européen Arctique, Université de Versailles Saint-Quentin-en-Yvelines (CEARC-UVSQ), France.
d’Etudes Economiques et Sociales de l’Environnement, Centre Emile Bernheim, Université Libre de Bruxelles,
(CEESE-CEB-ULB), Brussels, Belgium.
c College of Policy Science, Ritsumeikan University, Kyoto, Japan
d Centre de Recherche en Economie, Université Saint-Louis (CEREC-FUSL), Brussels, Belgium.
e Senior Adult Learning Center, Portland State University, USA.
b Centre
1
Objectives
• Build a model by linking an Input-output (I-O) table
to a System Dynamics (SD) model in order to
capture the complexity of an ecological-economic
system
• Apply the model to the Seine Estuary, France
• For this paper, policy implications for the restoration
of the estuary are NOT the main focus
– (we will address these in the next step)
2
1
25/03/2014
Motivation
• We need modeling techniques which can capture
the complexity of an ecological-economic system.
• Environmentally Extended I-O
– Captures detailed economic structures, but not dynamics
• Constant technical coefficients; Lack of feedback loops
• SD(a computer-aided approach to solving a system of nonlinear first-order differential equations)
•
Captures nonlinear dynamics and feedback loops, but not detailed
(disaggregated) economic structures
• It is technically possible to integrate I-O and SD.
• SD can be synchronized with SAP, Oracle, Microsoft Excel, GIS, etc.
3
Study Area: The Seine Estuary
• The nursery area for sole has been decreasing due to
economic activities (Rochette et al, 2010; Culliviez et al, 2008).
190
181.91
180
Nursery areas (km2)
170
160
150
139.67
140
127.94
130
122.77
120
111.74
110
Nursery habitats have been continually destroyed since
1834 by the construction of dykes and harbour
extensions for maritime transport, and by the
Normandy bridge.
Source: Cullivies (2008).
100
1830
1850
1870
1890
1910
1930
1950
1970
1990
2010
Years
Evolution of nursery areas of the internal part of the
Seine estuary
Source: Rochette, S.
4
2
25/03/2014
The Schematic Model
• SD on Powersim® is synchronized with I-O on Excel®.
Ecological System
(SD on Powersim)
Nursery Area in the
Seine Estuary
Carrying Capacity of
Sole
Fractional
Destruction Rate
Destruction Rate
Restoration Rate
Total Output
Initial Nursery Area
Restoration Policy
Economic System
(I-O on Excel)
Maximum Number of
Sole per km2 of
Nursery Area
Sole in the Seine
Estuary
Initial Stock of Sole
Net Birth
Average Weight per
Catch
Price of Sole per kg
Catch Rate
Fractional Catch
Rate
Weight of Caught
Sole
Change in Total
Output
Final Demand for
Sole
Intrinsic Growth
Rate of Sole
Total Output
Initial Total Output
Final Demand for
Sole
5
Simulation Results
• Preliminary results with three scenarios.
• Need to use optimization techniques to elicit practical policy
implications.
120,00
100,00
80,00
60,00
40,00
20,00
0,00
2008 2010 2012 2014 2016 2018 2020 2022 2024 2026
Final demand for sole
Final Demand for Soles (millions of
Euro)
Nursery Area in the Seine Estuary (km2)
Nursery area in the Seine Estuary
140,00
2,50
2,00
1,50
1,00
0,50
0,00
2008 2010 2012 2014 2016 2018 2020 2022 2024 2026
Baseline (No Restoration)
Baseline (No Restoration)
2% Restoration from 2018
2% Restoration from 2018
10% Restoration Every 5 Years from 2018
10% Restoration Every 5 Years from 2018
6
3
25/03/2014
Future Research Directions
• Feedback loops
– E.g., impacts of economic activities on the destruction of the nursery
• Delays
– E.g., dike construction impacts linger for several years (Culliviez, 2009)
• Ecological System
– Need to sophisticate the model structure of the ecological system
• Data Collection
– Collect “soft data” through, for example, expert meetings
• Optimal Restoration Policies under Uncertainties
– SD offers optimization techniques for analytically unsolvable models
7
4