> we are moving ever larger quantities of rock for ever-smaller returns --- when does that reach a point at which it no longer makes sense? In economics we dea

> we are moving ever larger quantities of rock for ever-smaller returns --- when does that reach a point at which it no longer makes sense? In economics we deal with supply and demand curves. If you price in the emissions, mining will at some point come into equilibrium with demand and continue to supply copper for those essential activities that require it, while forcing alternatives to switch to something else. For the specific case of copper, aluminum is a close substitute in most practical applications (or CCA composite wires, combining the advantages of both). The world reserves of bauxite seem sufficient for centuries at current rates of extraction. For high end applications like ship or wind turbine use, superconductor motors are becoming a reality.