The Disturbed Equilibrium Theory (DET) and Index (DEI): A Predictive Framework for Ecosystem Collapse and Renewal

Environmental crises such as shrinking lakes, land subsidence, and extreme weather are structured responses of natural systems to persistent human pressures. We introduce the Disturbed Equilibrium Theory (DET) and its operational metric, the Disturbed Equilibrium Index (DEI), to model and quantify ecosystem transitions from dynamic balance to collapse or renewal. DET posits that biophysical systems possess inherent self-regulation, striving for equilibrium; when human actions disrupt these pathways, nature responds in structured, and often catastrophic, ways to restore balance. The DEI integrates Human Pressure (H), Exogenous Stress (A), and Resilience (R) into a single time-indexed metric: DEI(t)= Ht+κA(t) /R(t) where κ is a calibration factor weighting external stress relative to human pressure. Six case studies—Lake Urmia, Aral Sea, the 2019 Shiraz flash flood, Amazon rainforest, Great Barrier Reef, and Hurricane Ian—spanning both chronic and acute crises, validate DEI’s ability to validate DEI’s ability to signal crises (DEI > 1.3) and highlight how resilience and connectivity shape divergent outcomes. Unlike frameworks such as Resilience Theory or Panarchy, which lack predictive and operational tools, DET/DEI unifies a conceptual law with a computable index and explicit governance pathways. It thus offers a scalable and transferable framework for sustainability science, climate adaptation, and environmental governance.