Three coupled stocks — Environmental health E, Social equity S and Economic viability Ec, each on 0–100 — evolve as a logistic system with cross-pillar feedback, the "systems thinking" the article describes: a change in one pillar ripples into the other two. The top diagram is a pannable/zoomable tank-and-flow view (drag to pan, scroll/pinch to zoom); the bottom panel is a live trend chart of all three stocks plus the Genuine Progress Indicator over simulated time.
footprint f = extraction·(1 − circularity)
dEc/dt = k1·(Ec/100)(1 − Ec/100) − k2·(1 − E/100)(Ec/100)
dE/dt = k3·(1 − E/100) − k4·f·(Ec/100)
dS/dt = k5·invest·(Ec/100)(1 − S/100) − k6·(1 − E/100)(S/100)
GPI = (E + S + Ec) / 3 (genuine progress, all three pillars)
Gap = GPI − Ec (what a GDP-only view misses)
- Extraction rate — the share of economic output drawn straight from natural capital (raises Ec, damages E).
- Circular-economy recovery — reduce/reuse/recycle: the fraction of that extraction pressure returned to the environment instead of consumed.
- Social investment — the share of economic surplus channelled into education, healthcare and equity (raises S).
- Environmental damage also feeds back into Economic and Social stocks (resource scarcity, unrest) via the
k2/k6 terms — an economy or society cannot outrun a collapsing environment indefinitely. Numerically verified: at the 55/20/30 defaults the maximum environmental regeneration rate (k3 = 1.2) is smaller than the damage rate at equilibrium (k4·footprint·Ec/100 ≈ 1.24), so E drifts to 0 over long runs even at "default" settings — that decay is the model's intended point, not a bug, and this 2D build reproduces it exactly rather than softening it.
- The GDP-only vs GPI gap readout is the simulation's version of the article's Genuine Progress Indicator: a policy that only tracks Ec can look successful while true, three-pillar progress quietly falls.