Independent input come from the outer space or from the core of the Earth:

• the energy sources for life at the surface of the planet. Their depleting is so slow as compared with civilisation time that they can be considered in a steady state, albeit with oscillations and disturbances:
  • Solar irradiation, the sole significant energy input from outside;
  • other electromagnetic or cosmic irradiation originating from the outer space;
  • geothermal activity, the largest meltdown on earth,in particular volcanic eruptions that spread large amounts of dust and gases into the atmosphere;
• tectonic movements.meteorites, events – frequent small ones, very rare large ones – that may induce definitive climate and geologic changes (e. g. extinction of the dinosaurs).