  This paper presents a conceptual model describing the medium and long-term
co-evolution of natural and socio-economic subsystems of Earth. An economy is
viewed as an out-of-equilibrium dissipative structure that can only be
maintained with a flow of energy and matter. The distinctive approach
emphasized here consists in capturing the economic impact of natural ecosystems
being depleted and destroyed by human activities via a pinch of thermodynamic
potentials. This viewpoint allows: (i) the full-blown integration of a limited
quantity of primary resources into a non-linear macrodynamics that is
stock-flow consistent both in terms of matter-energy as well as economic
transactions; (ii) the inclusion of natural and forced recycling; (iii) the
inclusion of a friction term which reflects the impossibility of producing
goods and services in high metabolising intensity without exuding energy and
matter wastes; (iv) the computation of the anthropically produced entropy as a
function of intensity and friction. Analysis and numerical computations confirm
the role played by intensity and friction as key factors for sustainability.
Our approach is flexible enough to allow for various economic models to be
embedded into our thermodynamic framework.
