Substitution, natural capital and sustainability

Substitutability of natural capital by human-made capital would seem to be limited. When human-made capital substitutes natural capital, there are currently commonly long-lasting negative impacts of such substitutions on constituents of natural capital. Long-lasting negative impacts on natural capital can be considered at variance with justice between the generations. In view thereof, there is a case to define (environmental) sustainability as keeping natural capital intact for transferral to future generations. A major problem for such conservation regards natural resources generated by geological processes (virtually non-renewable resources), especially regarding geochemically scarce elements. Substitution of virtually non-renewable resources by generating equal amounts of renewables has been proposed as a way to conserve natural capital. However, renewables substituting for fossil carbon compounds are currently associated with negative impacts on constituents of natural capital to be transferred to future generations. The same holds for the substitution of widely used geochemically scarce virtually non-renewable copper by abundant resources generated by geological processes. Though current negative impacts of substitutions on natural capital can be substantially reduced, their elimination seems beyond the scope of what can be achieved in the near future. The less strict “safe operating space for humanity”, which has been used in “absolute sustainability assessments” is, however, not a proper alternative to keeping natural capital intact for transferral to future generations.