An Input-Output/System Dynamics approach to ecological

An Input-Output/ System Dynamics Approach to Ecological Economic Modeling: An application to the Seine Estuary in France Takuro Ueharaa, Mateo Cordier b, c, Bertrand Hamaided and Jeffrey Weihe a

College of Policy Science, Ritsumeikan University, Kyoto, Japan Européen Arctique, Université de Versailles Saint-Quentin-en-Yvelines (CEARC-UVSQ), France. c Centre d’Etudes Economiques et Sociales de l’Environnement, Centre Emile Bernheim, Université Libre de Bruxelles, (CEESE-CEB-ULB), Brussels, Belgium. d Centre de Recherche en Economie, Université Saint-Louis (CEREC-FUSL), Brussels, Belgium. e Senior Adult Learning Center, Portland State University, USA. b Centre

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Objectives • Build a model which links an Input-output (I-O) table to a System Dynamics (SD) model to capture the complexity of an ecological-economic system • Apply the method 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!)

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Motivation • We need modeling techniques which can capture the complexity of an ecological-economic system. • Environmentally Extended I-O – Well-developed; an I-O is often readily available – 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

120 111.74 110 100 1830

1850

1870

1890

1910

1930

1950

1970

1990

Nursery habitats have been continually destroyed since 1834 by the construction of dikes and harbor extensions for maritime transport, and by the Normandy bridge.

Evolution of nursery areas of the internal part of the Seine estuary

Source: Cuvilliez (2008).

Source: Rochette, S. (2010)

2010

Years

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The Schematic Model • SD on Powersim® is synchronized with I-O on Excel®. Ecological System (SD on Powersim)

Economic System (I-O on Excel) Commodity ↓

Nursery Area in the Seine Estuary

Total Output

Initial Nursery Area

Restoration Policy

Carrying Capacity of Sole

Fractional Destruction Rate

Destruction Rate

Restoration Rate

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

Initial Total Output

Mining products & services Products from other industries

2009

2010

2011

2012

2013

1,781.3

1,837.0

1,891.1

1,951.7

2,015.3

117.1

111.2

114.4

117.9

121.6

125.5

58.3

56.6

58.1

59.6

61.3

63.0

318.4

298.4

312.4

323.8

336.4

349.6

25,751.8 24,545.5 25,427.9 26,222.4 27,113.8 28,052.2 2,139.6

1,975.3

2,095.4

2,178.0

2,269.1

2,364.9

Other non-metallic mineral products

1,429.7

1,373.1

1,411.0

1,453.7

1,501.6

1,552.5

Electrical energy, gas, steam and hot water

3,791.0

3,451.5

3,695.0

3,854.8

4,029.4

4,213.1

Construction work

Final Demand for Sole

2008 1,856.3

Coke, refined petroleum products and nuclear fuels

Services from other tertiary sectors

Intrinsic Growth Rate of Sole

Total Output

Year →

Products of agriculture, hunting and related services Products of forestry, logging and related services Fish and other fishing products; services incidental of fishing

Water transport services Supporting and auxiliary transport services; travel agency services Soles TOTAL OUTPUT →

49,374.8 47,865.1 49,193.5 50,449.8 51,926.8 53,475.1 7,344.0

7,214.6

7,128.2

7,356.0

7,592.6

417.8

370.5

403.7

424.1

446.1

7,854.9 469.4

2,408.1

2,291.6

2,379.9

2,454.8

2,539.5

2,628.6

1.9

1.7

1.6

1.6

1.5

1.5

95,009

91,336

94,058

96,788

99,892

103,166

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Simulation Results • Preliminary results with three scenarios. – 0% Restoration Every Year, from 2018 to 2028 (as a baseline) – 2% Restoration Every Year, from 2018 to 2028 – 10% Restoration Every 5 Years, from 2018 to 2028 140.00 120.00 100.00 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 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

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Future Research Directions • Feedback loops between an economic system and an ecological system – E.g., impacts of economic activities on the destruction of the nursery

• Delays – E.g., dike construction impacts that linger for several years (Cuvilliez, 2009)

• Ecological System – Need natural scientists’ advice to sophisticate the structure of the ecological system model

• Data Collection – Collect “soft data” through, for example, expert meetings

• Scale Mismatch? – Is the economy too big (monetarily) relative to the size of the ecological system? – Boundary of Economic System? Adjust I-O using RAS method?

• Optimal Restoration Policies – SD offers optimization techniques for analytically unsolvable models – SOPS (Stochastic Optimization in Policy Space)

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