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Ecological Macroeconomics &
Multi-Sector Growth

How resource metabolism, income distribution, and structural change interact within a multi-sector dynamical systems framework — bridging classical political economy with modern computational methods.

Dynamical systems Input-output Growth theory Climate policy Directed technical change Flaschel-Semmler EU KLEMS · WIOD · EORA

Research Programme

This research programme develops a family of multi-sector dynamical models rooted in the classical political-economy tradition — specifically the Flaschel–Semmler framework of cross-dual price-quantity adjustment — and calibrates them empirically against large international databases (EU KLEMS, WIOD, EORA). The unifying question is: how do sector-level fluctuations in prices, quantities, and environmental flows propagate through the input-output structure of production, and how can fiscal policy steer that propagation toward decarbonisation and macroeconomic stabilisation simultaneously?

Theoretical framework Cross-dual adjustment (laws of excess demand & excess profitability); composite Walrasian–Keynesian dynamics
Empirical strategy Mixed-effects varying-slopes regression on EU KLEMS; WIOD & EORA technology matrices
Policy tools studied Carbon taxes, green subsidies, price caps, profit caps, revenue-neutral tax-subsidy mixes
Countries Germany, France, Italy, Japan, Netherlands, United States (plus global EORA coverage)

Paper I — Journal of Economics and Statistics

Jahrbücher f. Nationalökonomie u. Statistik · 2024

Assessing the Speed of the Green Transition: Directed Technical Change in a Multi-Sector Growth Model

Oriol Vallès Codina & Willi Semmler

How fast can a modern economy decarbonise — and what does it take to hit the IPCC 1.5°C targets on time? This paper answers these questions using a multi-sector growth model in which a green sector and a carbon sector compete through cross-dual price-quantity dynamics. The adjustment coefficients are estimated empirically for six developed economies from EU KLEMS and WIOD data. Over 14,000 simulations varying tax rates, subsidy rates, cost efficiency, and initial investment ratios reveal a clear policy hierarchy: without fiscal policy, no economy reaches the IPCC target within any reasonable horizon. Carbon taxes on profits have the largest impact, green subsidies come second, and cost efficiency alone — even orders of magnitude above current levels — cannot compensate for the absence of public policy.

Key finding 1

Carbon taxes on profits are the single most powerful lever for decarbonisation speed — more than twice as effective as green subsidies in the simulation ensemble.

Key finding 2

Fiscal policy has its greatest effect at the earliest stages of the transition, supporting a "big push" logic: early public investment mobilises private capital into green sectors.

Key finding 3

Cost efficiency (relative capital intensity of the green sector) has a negligible impact on speed within realistic time frames — challenging pure technology-optimist narratives.

Policy implication

A revenue-neutral tax-subsidy mix — taxing carbon output to subsidise green output — is the minimum necessary instrument to reach IPCC targets. No policy = no target.

Selected figures

Cross-dual adjustment dynamics
Figure 1 — Phase-space dynamics Cross-dual adjustment of prices and quantities around the model's equilibrium. The oscillatory paths trace the competition between the carbon and green sector.
Estimated adjustment coefficients
Figure 2 — Empirical adjustment coefficients Mixed-effects varying-slopes estimates across six countries (EU KLEMS). Posterior distributions capture cross-country heterogeneity in price and quantity responsiveness.
No-policy baseline simulation
Figure 3 — No-policy baseline Without fiscal intervention, the green sector's output share rises too slowly to meet IPCC decarbonisation targets within any realistic horizon.
Tax-subsidy policy simulation
Figure 4 — Revenue-neutral tax-subsidy mix A carbon tax recycled as a green subsidy dramatically accelerates the phase-out of the carbon sector and the phase-in of green energy — meeting the IPCC target.

Paper II — Journal of Economic Behavior & Organization

JEBO · 2024

Stabilising Economy-Environment Interactions: A Multi-Sector Growth Model with Empirical Adjustment Dynamics

Oriol Vallès Codina & Willi Semmler

The COVID-19 pandemic and the Ukraine war exposed how poorly understood the propagation of macroeconomic shocks through input-output networks remains. This paper proposes a "composite" multi-sector growth model — integrating long-run Walrasian price dynamics, classical quantity adjustment, and short-run Keynesian markup pricing and demand-led investment — calibrated from the EORA global input-output database and EU KLEMS. The model functions like a machine-learning algorithm: adjustment coefficients are estimated via a mixed-effects hierarchical regression, then fed into forward simulations. The framework is then used to evaluate how taxes, subsidies, price caps, and profit caps can simultaneously stabilise macroeconomic fluctuations and reduce environmental pressures (carbon emissions, land use, water waste).

Key finding 1

The composite model reproduces the empirical spectral properties of sector-level price and quantity fluctuations — validating the Flaschel cross-dual framework as a data-driven alternative to DSGE.

Key finding 2

Price caps and profit caps outperform pure tax-subsidy instruments at stabilising economic volatility, but must be combined with green incentives to achieve environmental co-benefits.

Key finding 3

Input-output network structure matters: hub sectors (energy, food, chemicals) amplify or dampen shocks non-linearly — standard representative-agent models miss this topology.

Policy implication

Sector-specific industrial policy targeting the most central nodes of the production network is more effective than uniform carbon pricing at achieving simultaneous stabilisation goals.

Selected figures

Input-output network
Figure 1 — Global input-output network Network visualisation of the EORA input-output structure. Hub sectors (energy, food, trade) exhibit high betweenness centrality — their price-quantity dynamics propagate disproportionately to the rest of the economy.
Eigenvalue stability analysis
Figure 2 — Stability & oscillatory regimes Eigenvalue analysis of the composite adjustment matrix. The model admits both stable convergent and oscillatory trajectories depending on empirical coefficient magnitudes — captured fully in the mixed-effects estimates.
Empirical composite dynamics
Figure 3 — Calibrated composite dynamics Simulated sector-level price and quantity paths using empirical EU KLEMS coefficients. The model reproduces cyclical patterns consistent with observed macroeconomic fluctuations across all six countries.
Ecological simulation
Figure 4 — Economy-environment co-stabilisation Policy simulation showing how combined taxes and price caps reduce both economic volatility and environmental pressures (carbon, land, water) relative to the no-policy baseline.

Shared Theoretical Architecture

Both papers draw on the same underlying framework — the Flaschel-Semmler cross-dual adjustment system — and use the same empirical strategy (mixed-effects varying-slopes on EU KLEMS). They differ in focus: the JES paper isolates the speed of structural change (the green transition as directed technical substitution); the JEBO paper studies simultaneous macroeconomic and ecological stabilisation under a richer set of policies and a global input-output network.

Core equation Cross-dual dynamics: ṗ = α(Ap − p) & q̇ = β(q − Aq) with composite markup and free-entry terms
Estimation Stan/MCMC hierarchical regression; varying slopes by sector, no intercept; posterior predictive checks
Simulation Forward ODE integration with empirical initial conditions from EU KLEMS; 14,000+ scenario ensemble for JES
Lineage Flaschel (1987, 1992, 2010), Semmler (2011), Duménil & Lévy (1987, 1993), Goodwin (1967)